How Exercise Improves Microbiome Health (and Vice Versa)

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By Mary Grace Descourouez, MS, NBC-HWC 

The human gastrointestinal tract is home to trillions of microorganisms that create the gut microbiome. The gut is where the body digests and absorbs nutrients from our food and, therefore, where we get our energy to perform daily human functions. Microbiota are microorganisms in the gut microbiome that help the body harvest energy, fight pathogens, and regulate immunity. Having a high diversity of microbiota helps us to process food effectively, providing the substrates and nutrients needed to keep us going throughout the day. Therefore, it is crucial to make lifestyle choices that promote a healthy and diverse microbiome.

Many people know that a nutrient-rich diet contributes to a healthy microbiome, however, research shows that movement and exercise may also have a positive effect, and, inversely, a healthy microbiome may improve athletic performance.

“It is a relatively new field, but available studies suggest a bidirectional relationship between performance and the health of the microbiome,” says Anne Friedlander, PhD, Exercise Physiologist and Assistant Director of Stanford Lifestyle Medicine. “People who are more active have a healthier and more diverse microbiome, and that, in turn, provides the person with the nutrients required to enhance physical and cognitive performance. It is a mutually beneficial relationship.” 

How Exercise Improves the Microbiome

Movement and exercise have many benefits on our overall health, including positive effects on the microbiome. Studies show that athletes have a more diverse microbiome composition than non-athletes. Microbiome diversity is important because it helps make our food’s nutrients more bioavailable for optimal functioning of the body.

Another study found that active women were associated with high microbiome diversity compared to sedentary women. Specifically, researchers found that consistent physical activity increased the amount of 11 genera of “good” bacteria, including Bifidobacterium spp, Roseburia hominis, Akkermansia muciniphila, and Faecalibacterium prausnitzii. 

How the Microbiome Improves Athletic Performance

Just as exercise positively impacts the microbiome, emerging research shows that microbiome health may also play a part in enhancing exercise performance.

For example, a 2019 study showed that a specific gut microbiota in marathon runners may have enhanced their athletic performance on race day.  In this study, researchers collected fecal samples from the runners before and after the marathon and compared them to microbiota of non-runners. The “good” bacteria Veillonella emerged as the most common in the runners, especially post marathon. Veillonella is a bacterial strain that converts exercise-induced lactate into propionate, which is a natural enzymatic process known to enhance athletic performance.

Researchers then put the Veillonella bacteria from the marathon runners into lab mice who underwent a treadmill exertion test to investigate the hypothesis that this bacterial strain enhances athletic performance. The results showed the mice improved performance by 13 percent after inoculation. This study is one of the first to infer that a healthy microbiome could enhance athletic performance.

“We have a long way to go to fully understand the complex system that involves the microbiome and athletic performance, but the early data look promising regarding gut health and exercise,” says Dr. Friedlander.  “Exercise, along with eating fermented foods and fiber, is a great place to start if you want to improve your gut health and overall health.”

Probiotics, Prebiotics, and Postbiotics: What Are They and Why Are They Important?

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By Maya Shetty, BS

Key Takeaways:

  • Probiotic and prebiotic supplements lack substantial scientific evidence that they promote microbiome health. 
  • Rather than taking supplements, experts recommend eating fermented foods (probiotics) to promote microbiome diversity and fibrous foods (prebiotics) to feed and sustain “good” bacteria in the gut.  
  • Recommended fermented foods (probiotics): 
    • Fermented vegetables: kimchi, sauerkraut, and certain pickled vegetables
    • Fermented dairy: yogurt, cottage cheese, kefir, and certain cheeses
    • Fermented soy: tempeh and miso
  • Recommended high-fiber foods (prebiotics):
    • Legumes: lentils, chickpeas, black beans, and kidney beans
    • Seeds: chia seeds, flaxseeds, pumpkin seeds, and sunflower seeds
    • Whole grains: quinoa, brown rice, oats, and barley
    • Nuts: almonds, walnuts, pistachios, and pecans
    • Vegetables: broccoli, Brussels sprouts, artichokes, carrots, and sweet potatoes
    • Fruits: apples, pears, berries (raspberries, blueberries, strawberries), and bananas
  • Postbiotics, the byproduct of probiotic and prebiotic activity, not only reduce the risk of chronic diseases and support brain health, but also offer anti-inflammatory and beneficial metabolic effects.

Within our bodies, there exists a bustling community that often goes unnoticed but plays a pivotal role in our well-being—the microbiome. Understanding the impact of the microbiome on our health is not just a scientific curiosity, it’s a crucial aspect of our health that underscores our body’s complex equilibrium. Through continuous negotiations, our body and microbiome engage in a symbiotic relationship—a dynamic exchange where we provide our microbiome with nourishment and “good” inhabitants, and in return, it synthesizes beneficial compounds to support our health.

“We are, in essence, walking ecosystems. Our health is intimately connected to the trillions of bacteria, viruses, and fungi that make up this community,” states Sean Spencer, MD, PhD, Gastroenterologist and Physician Scientist at Stanford University.

The microbiome actively participates in various bodily functions, from aiding digestion and nutrient absorption to eliminating toxins and synthesizing vitamins and amino acids.

“The influence of our microbiome extends far beyond the confines of the digestive system, reaching major body systems like the immune system, metabolism, and the central nervous system,” states Rachele Pojednic, PhD, Stanford University  nutrition and exercise scientist.

While the definition of a healthy microbiome remains unclear, the majority of studies find that high microbiome diversity is linked to better health outcomes. “A healthy microbiome is one that is equipped to process a diverse array of dietary fiber to produce  health-promoting compounds for our body,” states Dr. Spencer. “Low microbiome diversity is linked to various health conditions, including diabetes and obesity and likely has reduced fiber-degrading potential and lower production of health promoting compounds.”

A recent study revealed that the average Californian has a microbiome that contains 277 microbial species, a stark contrast to the average of 730 found in non-industrialized populations. This finding aligns with a mounting body of evidence suggesting that modern lifestyles and Westernized diets have significantly depleted the essential diversity of our gut microbiome.

Therefore, many individuals have sought ways to manipulate their microbiome and increase its diversity via supplementation. Commonly referred to as probiotics and prebiotics, these supplements have surged in popularity, achieving sales of $35 billion in 2015 and projected to reach $65 billion by the end of 2024.

Despite their widespread use, there is significant confusion about what they are, where to find the best ones, and what they can and can’t do. Regardless, experts say the most powerful and beneficial sources for all your biotic needs are often overlooked (hint: they are in your refrigerator).

What Are Probiotics and Why are They Important?

Probiotics are live microorganisms that are consumed for health benefits and typically found in fermented foods like yogurt, kimchi, and sauerkraut. They play a crucial role in supporting our gut by introducing beneficial bacteria to our microbiome community. Simultaneously, they reduce the proliferation of harmful bacteria by constraining their available space for growth.

Upon hearing the term “probiotics,” many individuals associate it with the supplement pills that have long been advertised to improve digestive health. However, these supplements are not recommended over food, as they can displace favorable microbial residents in the gut.

“The doses of microbes found in supplements are overly potent, with billions to trillions of microbes, far exceeding the amounts in fermented foods, which contain hundreds of thousands to millions,” states Dr. Pojednic. “In this context, more is not better; natural sources provide a gentler, more physiologically effective way to support your microbiome.”

Another problem with probiotic supplements is they are created under the assumptions that the same bacteria strains are beneficial to everyone. But research indicates that microbiota composition and function varies significantly among individuals. What benefits one person may not necessarily work for another, and the scientific community is yet to develop the means to tailor probiotic prescriptions on an individual basis. Moreover, most beneficial gut bacteria that promote health are not yet available in probiotic supplement form.

“While healthy microbiomes may display certain shared characteristics, such as diversity, the specific types of bacteria that truly confer benefits remain unclear. Therefore, the limited selection of bacterial strains found in probiotic supplements may not be what your gut needs,” states Dr. Spencer.

Rather than taking probiotic supplements, Spencer and Pojednic recommend increasing the intake of probiotics by consuming fermented foods. Furthermore, fermented foods contain metabolic byproducts and other signaling molecules that probiotic supplements alone do not. Growing evidence suggests these metabolites confer additional health benefits and may aid the colonization of beneficial bacteria in our gut.

Fermented foods have been associated with enhancing microbiome diversity and overall health in several studies. A notable study was conducted at Stanford University, where participants adhered to a diet rich in fermented foods. Following a ten-week regimen of daily intake of five servings of fermented foods, participants demonstrated increased microbiota diversity and a notable reduction in inflammation in the body.

Dr. Spencer highlights this intriguing correlation, stating, “As the diversity of participants’ gut microbiome increased, there was a simultaneous decrease in various markers of inflammation, emphasizing the beneficial impact of fermented foods on overall health.”

“It’s important to remember that not all fermented foods have probiotic properties. When identifying probiotic foods, look on the labels for terms like ‘live cultures’ or ‘active cultures.’ Additionally, look for foods in the refrigerated section of the grocery store,” states Dr. Pojednic.

Should I Take Probiotics After Antibiotics?

A popular strategy to mitigate the depletion of one’s microbiota following antibiotics is to take probiotic supplements. However, a study revealed that probiotic supplements could unintentionally impede the normal recovery of the microbiota by displacing beneficial microbes in the gut. Participants who received the probiotic supplement took more than five months for their microbiome to recover, in contrast to those who received a placebo, whose microbiome returned to normal within three weeks. These findings suggest that taking probiotic supplements after antibiotic treatment did not help balance the microbiome; in fact, these supplements impaired its recovery.

“When this trial came out a few years ago, it created a paradigm shift in the field by showing that taking probiotics after antibiotics may actually delay the recovery of your microbiome,” states Dr. Spencer. “Now, I spend a lot of my time in GI clinics convincing people not to take probiotic supplements after antibiotics.”

While probiotic supplements are often used to alleviate symptoms linked to gastrointestinal conditions, such as irritable bowel syndrome and diarrhea, the American Gastroenterological Association does not recommend probiotics for the treatment of any adult gastrointestinal conditions outside of pouchitis. In any case, it’s advisable to consult with a physician before incorporating a probiotic supplement into one’s routine.

“As of now, there are very few probiotic supplements that have strong evidence of their beneficial effect in treating gastrointestinal disease,” states Dr. Spencer. “Nevertheless, this landscape is evolving quickly with ongoing research and advancements in probiotics. I’m hopeful that the next generation of probiotics will target GI disease more effectively.”

What Are Prebiotics and Why are They Important?

After establishing a diverse and healthy microbiome (by consuming a variety of probiotic foods), it becomes crucial to actively sustain it. What you eat directly fuels your microbiome community and determines which microbes will flourish and which will parish in the competitive landscape of your gut.

Prebiotics are nutrients that foster the growth and proliferation of beneficial bacteria in the gut, ultimately contributing to overall gut health. The main prebiotics our microbiome thrives on are known as microbiota-accessible carbohydrates (MACs), commonly referred to as dietary fiber. These complex carbohydrates, found in fruits, vegetables, whole grains, legumes, and other plant materials, resist our body’s degradation and absorption processes. This digestive resistance allows them to reach the colon still intact, providing a feast for our gut bacteria.

For individuals consuming diets high in sugar, fat, and protein, but lacking in dietary fiber, these macronutrients will break down and enter the bloodstream before reaching our colons. As a result, the typically diverse microbial community found in our colons will starve. Over time, the microbiome, in its quest for sustenance, may resort to consuming the gut’s protective mucus layer. This degradation can lead to a cascade of adverse effects, including inflammation within the gastrointestinal tract.

“Without the nourishment provided by fiber, the microbiome is left to fend for itself, potentially resulting in detrimental consequences for both its composition and the overall health of the gut,” states Dr. Spencer. “Eating prebiotic-containing foods is critical to sustain a healthy microbiome.”

In recent years, prebiotic supplements have gained popularity, however, our experts advise opting for fibrous foods over supplements to meet your microbiome’s probiotic requirements. This preference is rooted in the fact that foods offer a diverse array of fiber types, whereas supplements commonly feature a single type. The consumption of a singular fiber type restricts the nutritional support available to our microbiome, and can limit overall diversity that is crucial for a healthy microbiome. Moreover, fiber-rich foods offer various nutritional health benefits not found in supplements. Dr. Spencer suggests that if occasional supplement use is preferred to meet prebiotic needs, choosing supplements with a mix of fiber types is advisable. Nevertheless, opting for fiber-rich foods proves to be a more dependable and cost-effective source.

While more research is needed to fully understand the microbiome and how probiotics and prebiotics work in harmony, it’s reasonable to infer that the presence of one may enhance the function of the others. To promote microbiome diversity and a healthy gut, it’s essential for one’s diet to be a balanced combination of fermented foods (probiotics) and dietary fiber (prebiotics).

“My favorite breakfast is yogurt (a probiotic food) topped with berries and whole-grain granola (which are prebiotic foods). In one delicious meal, I fulfill all my biotic needs,” states Dr. Pojednic.

What Are Postbiotics and Why are They Important?

While many have heard of probiotics and prebiotics, the term postbiotics is relatively new. Postbiotics are the byproduct of probiotic and prebiotic activity. Essentially, they are the waste products left behind by the breakdown of fiber by the bacteria  in your microbiome.

These byproducts can be both beneficial and harmful to your health. The breakdown of fiber yields a treasure trove of beneficial postbiotics. Among these are essential elements such as vitamins, enzymes, amino acids, and short-chain fatty acids (SCFAs). One standout SCFA is butyrate, a superpower molecule throughout the body that plays a pivotal role in various aspects of health. Linked to a reduced risk of chronic diseases, butyrate also exhibits anti-inflammatory properties, supports brain health, and has beneficial metabolic effects.

Conversely, the breakdown of meat in the digestive process yields molecular byproducts such as choline and L-carnitine. In the microbiome, these compounds get broken down further into trimethylamine (TMA), which is subsequently absorbed by the circulatory system and oxidized in the liver to form trimethylamine N-oxide (TMAO). Elevated levels of TMAO have been associated with an increased risk of clot-related cardiovascular events. Intriguingly, a study conducted at Stanford suggests that refraining from meat consumption for eight weeks could potentially suppress the “bad” bacteria associated with TMA production when reintroducing meat into the diet, however, additional research is required to validate this hypothesis.

Postbiotic Supplements

While the concept of postbiotics is relatively new, the popularity of postbiotic supplements is on the rise. Butyrate supplements, for instance, are becoming increasingly common. It is essential to recognize that a deficiency in Butyrate might signify an underlying issue with one’s diet and digestive system, which a supplement alone may not rectify. The most effective strategy for boosting postbiotics involves embracing a diet rich in fermented food and fiber.

Take Home Message: Food is Better than Supplements

Compared to supplements, fermented and fibrous foods provide a diverse array of microorganisms that benefit your microbiome. Moreover, supplements miss out on the synergistic biotic combination of components found in whole meals. Research consistently underscores the pivotal role of diet in shaping the composition and function of a healthy gut microbiome, serving as the most comprehensive and research-backed biotic source.

“We have abundant data to demonstrate that food affects the microbiome. And while supplements certainly have their place–to address nutrient deficiencies and improve specific health outcomes–the evidence for the supplements widely marketed for benefiting the gut are limited at best,” states Dr. Pojednic. “To ensure your microbiome is getting the sustenance it needs, it is best to get your probiotics from fermented foods and prebiotics from high-fiber foods, which have the added bonus of numerous other health benefits.”

Another thing to consider is safety and efficacy of the supplements. Most supplements are loosely regulated by the FDA, meaning manufacturers don’t need to prove safety and efficacy. For this reason, it’s always better to get a nutrient or biotic source from food over supplementation unless it has been recommended by your physician or dietitian.

Most importantly, relying on biotic supplements cannot remedy the consequences of a poor diet. Long-term dietary habits play a pivotal role in the adaptability of the gut microbiome, with the consumption of diverse fermented and high-fiber foods being paramount. As our dietary habits evolve, so does the microbiome, adapting and diversifying to create a resilient and well-balanced ecosystem. In essence, the journey to a healthier gut extends beyond the allure of quick-fix supplements.

“While there is some regulation on manufacturing and marketing of supplements, enforcement is rare unless there is a well-documented negative health effect. Third party testing is key to ensuring you are consuming a safe product. Otherwise, you can fall prey to deceptive claims, mislabeled ingredients or possible contamination,” states Dr. Pojednic. “Safe, well studied supplements have their place, but we just aren’t there yet with these products.”

With ongoing advances in microbiome research, the future may hold more precise probiotic, prebiotic, and postbiotic interventions, potentially enhancing the effectiveness of supplements. However, the foundation of gut health remains deeply rooted in dietary habits, emphasizing the enduring value of natural, food-based approaches over supplementation.

Microbiome Expert Sean Spencer, MD, PhD: On a Mission to Prove that Food is Medicine

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By Sharon Brock, MEd, MS

Sean Spencer, MD, PhD is a Gastroenterologist and Physician Scientist at Stanford University School of Medicine. Along with seeing patients in the clinic, Spencer conducts cutting-edge research on the microbiome in the Sonnenburg Lab. In his research, Spencer focuses on how nutrition affects the microbiome and the immune system, as well as how our diet can prevent and treat gastrointestinal disease and potentially increase longevity.

“There’s a clear association between the microbiome and healthy aging. Studies of centenarians show a different microbiome configuration and metabolite production compared to those with a shorter life span and unhealthy aging,” says Spencer. “The microbiome is a key aspect of lifestyle medicine because what we eat and how we exercise affects our microbiome composition.” 

 The Medical Path

 Growing up amidst the rich agricultural tradition in Madison, Wisconsin, Spencer learned from an early age the importance of nutritious food for optimal health. As an undergraduate at the University of Wisconsin, Spencer majored in medical microbiology and immunology, and knew since his sophomore year that he wanted to practice medicine.

“After taking a human physiology course, I just knew that learning as much as I could about the human body and using that knowledge to help people was the only thing I wanted to do,” says Spencer. “As an undergrad, I also discovered that I could conduct research while caring for patients, and that clarified my career path further.”

These career goals prompted Spencer to pursue an MD-PhD program in immunology at the University of Pennsylvania, which he completed in 2015.

“In graduate school, I realized how our diet has a profound impact on the microbiome, and can directly influence the immune system,” says Spencer. “You want to think of the three aspects [nutrition, microbiome, and immune system] at the three corners of a triangle. They each impact the other.”

After completing an internal medicine residency at the Harvard-affiliated Massachusetts General Hospital, Spencer came to Stanford in 2017 for a fellowship in gastroenterology (GI).

“I came to Stanford specifically to work with Justin Sonnenburg, so it was great to be accepted to both the GI clinical program and his lab,” says Spencer. “What I love most about Stanford are the people and the creativity. This focus on the microbiome and nutrition is unique to Stanford and I’m glad to be part of a community that thinks about lifestyle medicine in both research and clinical care.”

Living His Dream

For the last three years, Spencer has been a practicing, board-certified GI physician at Stanford Medicine and a researcher in one of the most prestigious microbiome labs in the country. Spencer lights up when he talks about his current research on the small intestine microbiome:

“Most microbiome studies look at poop, which represents the very end of the GI tract, but the small intestine is 20 feet long, and researchers have sampled almost none of it,” says Spencer. “We’ve developed a novel technology to sample and investigate the microbiota [bacteria] of the small intestinal microbiome, which has been a huge blank space for the longest time.”

The small intestine is where many nutrients, including glucose, are absorbed into the bloodstream. Since high glucose levels are linked to diabetes and obesity, Spencer believes this research will potentially lead to the development of therapies to be used alongside lifestyle medicine, to enhance its benefits, for individuals with these medical conditions.

Spencer also studies hormones in the small intestine, such as Glucagon-like peptide-1 (GLP-1), which is the hormone targeted in the popular weight-loss drugs Ozempic and Wegovy. “The new GLP-1-targeted medications are powerful and amazing drugs, but it’s important to recognize that we have the power to regulate these hormonal pathways with our diet and lifestyle choices,” he says.

Although his work in the lab is a source of fulfillment, Spencer also enjoys bringing his research findings directly to his patients as a GI physician. Spencer is able to offer this bench-to-bedside level of care since he attained both a medical degree and a PhD in immunology.  

“I’m most proud that I have the skillset to listen to patients and identify what they need clinically, and then do the research to fill in the gaps and conduct clinical trials to develop new therapies to help them,” says Spencer.

Looking to the Future

Spencer’s future plans are to work in a clinical setting where he can continue to see GI patients and perform clinical trials on nutrition-microbiome-immune research. Studies from the Sonnenburg lab he would like to continue are testing the anti-inflammatory effects of fermented foods, which help treat food allergies, and the mechanisms by which our diet, microbiome, and immune system impact each other.

Regarding patient care, Spencer takes a “food is medicine” approach and plans to conduct more research to back up that message. “My future goal is to perform research that reinforces the recommendations of lifestyle medicine; to build the evidence-base for types of food that promote a healthy microbiome and prevent and treat disease,” says Spencer. “This research will help us understand what aspects of food are critical for promoting health and wellness and has real potential to offer improved dietary advice and to help our patients promote health through what they eat.”

Dr. Spencer’s Science-Based Smoothie for Gut Health

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By Maya Shetty, BS

In the complex world of gut health, finding straightforward solutions that effectively support the microbiome can be challenging. For this reason, Sean Spencer, MD, PhD, Gastroenterologist and Physician Scientist at Stanford University, created a meticulously engineered morning smoothie recipe to support his own gut health. Guided by his deep understanding of the gut’s delicate ecosystem, this smoothie is not just a meal but a strategic tool for fostering a flourishing microbiome.

Ingredients:

  • 1 cup spinach
  • ½ avocado
  • ½ apple
  • 1 tsp green banana flour
  • 1 tsp L-glutamine powder
  • 1 scoop (20 grams) pea protein powder
  • Top up with liquid of choice: water, coconut water, milk or nut milk (without additives)

Creating the Base

Dr. Spencer tailors his morning smoothie base with a focus on nutrient density and diversity, recommending a blend of apples, spinach, and avocado. Yet, he emphasizes the flexibility of the recipe to accommodate personal tastes and digestive responses. For those who find certain fruits, like apples, lead to bloating, Dr. Spencer says they can be easily substituted with other fruits like bananas or blueberries. 

“I find spinach, apple, and avocado make a tasty combination, yet the door is open to experiment with different fruits to achieve a healthy blend of nutrients and fiber,” he states.

Dr. Spencer points out the unique contribution of avocados to the smoothie. Unlike many fruits, avocados are rich in healthy fats, crucial for delivering steady energy throughout the day. Moreover, they are remarkably high in fiber, with half an avocado offering six to seven grams, making up about a quarter of the USDA’s daily recommended fiber intake. This dual benefit of avocados enhances the smoothie’s nutritional profile, making it a powerhouse of sustained energy and digestive health.

When it comes to liquid choices, almond milk is Dr. Spencer’s preferred option, but he notes the suitability of any type of milk or coconut water as long as it’s free from inflammatory additives, such as added sugars and thickeners, which can negatively impact the microbiome when consumed regularly. He also cautions against the deceptive practices of some brands that claim no added sugars while employing enzymes that convert complex carbohydrates into simple sugars (such as alpha-amylase added to oat milks), effectively sneaking in unwanted sugars.

“To ensure the healthiest choice for your microbiome, I recommend opting for products with short and simple ingredient lists,” he states.

Pea Protein Powder

Dr. Spencer chooses pea protein for its gentle impact on the digestive system and its impressive nutritional profile. It also boasts a comparable protein content to whey and includes all nine essential amino acids—vital nutrients your body is incapable of producing on its own.

Dr. Spencer advises that choosing the right protein powder for your gut is not about type, but rather additives. Most protein powders on the market, including pea protein, are formulated with emulsifiers. These additives, such as soy lecithin, cellulose gum, xanthan gum, guar gum, acacia gum, and polysorbate 80, are used to enhance the powder’s mixability in liquids. Despite their practical benefits, emulsifiers come with a downside–they’re notoriously harsh on the microbiome.

Recent research has shed light on the detrimental effects of common emulsifiers, revealing their capacity to directly alter the gut microbiota and incite inflammation. Such disruptions can compromise an otherwise healthy microbiome, underscoring the importance of choosing products wisely. A randomized controlled trial illuminated the extent of this impact, showing that the inclusion of emulsifiers in the diet over a mere 11-day period led to a noticeable decline in microbiome diversity and a reduction in the production of beneficial metabolic byproducts, or postbiotics.

Green Banana Flour (Resistant Starch)

Green banana flour enriches the microbiome with its high resistant starch content, a form of fiber with powerful benefits to the microbiome. Resistant starch has many health benefits and earns its name for its ability to bypass digestion in the small intestine, journeying instead to the large intestine. Here, it serves as a vital food source for beneficial gut bacteria, promoting a robust and healthy microbiome. The fermentation of resistant starch by these microbes results in the production of valuable postbiotics, such as short-chain fatty acids, essential for maintaining gut health. As bananas ripen they convert their starch to simple sugars, while the starch in green bananas remains intact, retaining its prebiotic properties. 

Dr. Spencer also mentions other fiber supplements like psyllium husk, which, although beneficial for digestion and adding moisture to bowel movements, does not serve as a fermentable food source for the microbiome. This distinction highlights the importance of choosing fibers that not only facilitate physical digestion but also actively contribute to the microbiome’s health.

“Other prebiotic supplements and sources exist. However, I choose to supplement with a resistant starch source because it has strong evidence that it is an accessible and fermentable source of fiber for microbiome,” he says.

While Dr. Spencer regularly uses green banana powder as a prebiotic supplement, he emphasizes the significance of incorporating a variety of fiber sources into one’s diet, noting this shouldn’t be the only fiber source in the day. 

“A diverse intake of fibers is crucial for a thriving microbiome, and I recommend consuming other prebiotic-rich foods such as potatoes, whole grains, beans, legumes, nuts, seeds, and a wide array of fruits and vegetables throughout the day,” he says.

L-Glutamine Powder

L-Glutamine offers a range of benefits for gut and microbiome health, such as reducing GI symptoms after morning workouts. It’s also recognized for its role in maintaining the integrity of the intestinal lining and reducing the inflammatory response during gut lining irritation. 

Furthermore, L-Glutamine serves as a vital energy source for the cells within the small intestine. This attribute is essential for maintaining intestinal health and addressing conditions where impaired intestinal barrier is present because it decreases gut permeability and reinforces the intestinal barrier.

 

More Than a Gut Feeling: How Your Microbiome Affects Your Mood

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By Maya Shetty, BS

Key Takeaways: 

  • The gut and brain are in constant communication through the gut-brain axis, which involves the nervous system, endocrine system, metabolic system, and immune system pathways.
  • Gut microbes produce neurotransmitters, hormones, and metabolites that can affect our emotions, thought processes, and behaviors.
  • Eating foods high in probiotics (such as fermented foods) and prebiotics (such as high-fiber foods) can improve the gut microbiome and mental health.
  • Processed food consumption negatively alters the gut microbiome, leading to adverse mental health effects via the gut-brain connection. 
  • In addition to diet, meditation and cognitive-behavioral therapy have shown to improve the gut microbiota composition, positively influencing the gut-brain axis.

When it comes to mood swings and mental state, the brain is often the first suspect. Yet, the trillions of microbes living in our gut, known as our microbiome, hold significant sway over our daily emotions and long-term mental health. This is because our microbiome and brain are in constant communication, influencing one another’s next move via the gut-brain axis.

“The complex interplay between our microbiome and brain is a testament to the body’s remarkable interconnectedness. It’s not just about gut health or mental health; it’s about how each influences the other in profound ways,” states Sean Spencer, MD, PhD, Gastroenterologist and Physician Scientist at Stanford University. 

The Gut-Brain Axis

The gut-brain axis represents a bidirectional communication system that intricately links the brain’s emotional and cognitive centers with the digestive system’s physiological processes. This complex network connects the central nervous system (CNS)—comprising the brain and spinal cord—and the enteric nervous system (ENS) within the gut using biochemical and physical pathways.

The ENS is an elaborate mesh-like system embedded in the gut lining, housing an astonishing 200 to 600 million neurons. Dubbed our “second brain,” this vast neural network, which spans from the esophagus to the rectum, contains many of the same structural elements as the brain.

“Our gut can be thought of as having its own brain, replete with motor neurons, sensory neurons, and neurotransmitters. In fact, our ‘gut brain’ contains more of some neurotransmitters, like serotonin, than the brain in our head,” states Dr. Spencer.

Instead of processing thoughts and emotions, our second brain focuses on orchestrating the digestion of food, absorption of nutrients, and intestinal motility (the movement of material from one end to the other). This unique system is equipped with its own reflexes and sensory capabilities, enabling it to adapt to the gut’s distinct conditions in real-time, independent from the brain’s oversight. In fact, studies have found the gut could still operate without direction from the brain. Under normal conditions, however, our gut and brain lean on each other to maintain homeostasis throughout the body using their intricate communication network.

The Vagus Nerve

The vagus nerve, one of the longest nerves in the body, forms the most direct link between the brain and the gut. It begins at the brainstem and stretches down to the abdomen, interfacing with various organs throughout its path. This nerve acts as a bidirectional channel, enabling the rapid exchange of signals from the brain to the gut and vice versa. 

Beyond the anatomical connection through the vagus nerve, the communication between the brain and gut includes endocrine (hormonal signals), metabolic, and immune routes. This continuous communication allows the brain and gut to be in sync. This expansive network highlights the gut-brain axis’s complexity, integrating diverse physiological signals to maintain mind and body balance.

The Microbiome’s Role in Mood

The key signaling molecules involved in the gut-brain axis are produced by the trillions of microbes making up our microbiome.  These microbes exist alongside the intestinal cells of the gut, which contain ENS neurons. This close proximity facilitates a dynamic exchange of signals between the microbes and the ENS neurons in the gut.

As research delves deeper into this symbiotic relationship, it has become apparent that our microbiome exerts a profound influence on the communication that flows through the gut-brain axis—so much so that it’s increasingly referred to as the microbiome-gut-brain axis. 

“Increasing evidence is showing that bacteria in the gut, and the byproducts they produce, affect mood, cognition, and behavior,” states Dr. Spencer.

Serotonin, Dopamine, and other Neurotransmitters

Neurotransmitters are crucial for communication within and between our brain and gut. Interestingly, the microbiome not only responds to neurotransmitters from the brain but also produces these same neurotransmitters that regulate thoughts and emotions, such as serotonin, dopamine, norepinephrine, and GABA.

“Serotonin, widely recognized for its role in mood regulation within the brain, also serves as a key signaling molecule in the gut. Remarkably, microbes in the gut are thought to be responsible for producing 95 percent of our body’s serotonin,” states Dr. Spencer.

Furthermore, the microbiome’s role extends to influencing neurotransmitter production throughout the body. Gut bacteria and our diet combine to provide and synthesize the tryptophan needed for serotonin production. 

“Variations in gut bacteria populations can alter the availability of tryptophan, impacting serotonin synthesis in the brain, which, in turn, influences our mood and behavior,” states Dr. Spencer.

Regulation of Hormones

The gut microbiome plays a pivotal role in regulating hormone secretion by gut cells, notably affecting hormones such as leptin, ghrelin, and insulin. These hormones are essential in communicating with the brain to regulate sensations of hunger and satiety and are also linked to influencing learning, memory, and emotions. Furthermore, the brain contributes to this dialogue by releasing hormones that modulate gut function, establishing a dynamic feedback loop between the brain and the gut.

Postbiotics

Postbiotics, the non-live byproducts of microbiota processes, are also integral to brain health. Microbial activity in the gut creates a variety of postbiotics, such as amino acids (the building blocks for neurotransmitters), glucose (which influences the brain’s energy metabolism), and fatty acids (which are crucial for brain development). These postbiotics serve as nutrients for the brain and are delivered from the gut to the brain through the bloodstream.

Recently, short-chain fatty acids (SCFAs), the primary metabolites derived from the microbial breakdown of dietary fiber, have garnered significant research interest for their wide-ranging positive impacts on brain health. SFCAs help strengthen the blood-brain barrier—a critical defense that shields the brain from potentially harmful substances while ensuring the smooth transit of vital nutrients— and exhibit powerful anti-inflammatory properties. These properties allow SCFAs to effectively modulate immune responses within the brain, significantly reducing neuroinflammation. Considering their comprehensive benefits, SCFAs are increasingly recognized as pivotal contributors to the dialogue within the microbiota-gut-brain axis, highlighting their vital role in supporting cognitive health.

Inflammation and Immune System

Gut microbes play a pivotal role in our body’s inflammation and immune responses, which directly impacts the integrity of the gut-brain axis. This communication network between our gut and brain is safeguarded by two critical barriers: the intestinal mucosal barrier and the blood-brain barrier. 

These barriers function as regulatory gatekeepers, managing the flow of information and maintaining the delicate balance within this network. Their permeability, however, is not static and can be influenced by various factors such as stress and inflammation, leading to fluctuations in gut-brain communication that depend heavily on an individual’s physiological state. As such, immune system activity in our gut has indirect, but significant, implications in the brain.

“An unbalanced immune response in the gut can increase the permeability of the intestinal lining—a condition commonly referred to as ‘leaky gut.’ This increased permeability allows substances that should remain within the confines of the digestive tract to enter the bloodstream and even to cross into the brain, potentially causing inflammation and contributing to the onset of various mood related  symptoms and conditions over time,” states Dr. Spencer. “I have seen the clinical implications of this in my patients, as those experiencing gut health issues are more likely to report low energy, brain fog, and anxiety.”

Nurturing the Gut for Better Mood

Research has revealed a complex network of bidirectional interactions linking the nervous system, the gut, and the microbiome. This dynamic interplay grants the microbiome a powerful influence over our psychological state. As a result, the health of our microbial community is recognized as a crucial factor in determining our daily mood and broader mental state. 

Dr. Spencer reinforces this connection by emphasizing the power of dietary choices: “Diet is the most modifiable and accessible way for people to promote a healthier microbiome.”

Diet plays a crucial role in shaping the composition and functionality of our gut microbiota. Consuming healthy foods fosters an environment where “good” microbes thrive, producing byproducts that benefit our mental health. Conversely, indulging in highly processed foods can tilt the balance in favor of “bad” microbes, leading to the production of inflammatory byproducts that negatively impact our mental well-being. As such, studies have focused on identifying dietary changes that can alleviate symptoms of depression, anxiety, and other mental health concerns. 

Observational studies have found that following a healthy, balanced diet, like the Mediterranean diet, as well as steering clear of pro-inflammatory foods and highly processed foods is linked to a reduced risk of depression. Randomized control trials have shed light on the advantages of consuming foods that positively affect microbiome health and composition. Following a “psychobiotic diet,” which focuses on prebiotic- and probiotic-rich foods and limits inflammatory items like sweets, fast food, and sugary drinks, has been linked to reduced perceived stress. Notably, greater adherence to this diet leads to more significant stress reduction. Prebiotic foods in this diet include fruits, vegetables, whole grains, and legumes, all high in soluble fiber, whereas probiotic foods consist of fermented items like kefir and yogurt. 

How Fiber Affects Mood

Another randomized control trial discovered that a high-prebiotic diet improved mood, anxiety, stress, and sleep in adults with moderate psychological distress. This diet involved consuming at least seven daily servings of soluble fiber-rich foods such as asparagus, garlic, onion, oats, whole wheat, and beans.

Interestingly, this study found that probiotic supplements did not yield mental health benefits, suggesting that the consumption of probiotic foods, rather than supplements, might be essential for mental health improvements. These studies highlight the potential of dietary interventions in enhancing mental health through gut-brain communication.

Considering the health of our microbiome requires not only focusing on what foods to incorporate into our diets but also which ones to avoid. Processed foods, a staple in Western diets for their convenience and taste, pose substantial risks to our microbiome’s environment. These items often contain heavily modified ingredients like added sugars, hydrogenated fats, processed meats, and artificial additives to enhance flavor and appearance. Common examples are sugary snacks, fast food such as burgers and fries, instant noodles, sodas, and pre-packaged meals. Consuming these items can disturb the balance of the gut microbiome, provoke inflammation, and adversely affect mental health via the gut-brain axis.

“I advise my patients to prioritize a diet high in whole foods and plants and to steer clear of processed and ultra-processed items, which are high in additives and preservatives that can disrupt the healthy bacteria in the gut,” states Dr. Spencer. “Moreover, I recommend dietary adjustments over the use of supplements like probiotics and prebiotics because food provides a necessary array of nutrients and fiber that currently available supplements cannot yet replicate.”

While the connection between diet and mental health is compelling, it’s important to recognize that food should not be seen as the sole treatment for mood disorders. Especially in cases of severe depression and suicidal thoughts, professional medical advice and treatment are paramount. Diet can play a supportive role in managing mild to moderate forms of depression and anxiety, complementing traditional treatment methods and contributing to overall mental health resilience.

Nurturing the Brain for Better Gut Health

While the microbiome plays a crucial role in shaping our daily mood and overall mental health, conversely, the brian profoundly influences both the composition and functionality of our microbial communities.

Decades of evidence have demonstrated how stress negatively impacts the gut microbiome, both directly affecting the gut microbiota and indirectly altering the gut environment. This is in large part due to the connections between the CNS and ENS, where activation in one system can trigger responses in the other. 

Excessive stress impacts gut transit and motility, leading to reduced nutrient delivery to the microbiome and consequently affecting its growth and diversity. Additionally, stress can impair the secretion of mucus by gut cells, weakening the intestinal mucosal barrier that protects our microbiome. Even short-term stress has the power to significantly alter the microbial community composition, diminishing both its diversity and population.

Improvements at the brain level, such as through cognitive-behavioral therapy (CBT) or meditation, can positively influence gut-microbial composition and function. A study involving participants with Irritable Bowel Syndrome who underwent CBT not only noted changes in brain activity but also observed alterations in the relative abundances of gut microbes. The specific CBT approach taught patients informational processing skills, fostering more flexible thinking about situations and reducing stress.

Similarly, another study explored the potential influence of long-term, regular meditation on the gut microbiota. Participants who practiced meditation exhibited distinct changes in the composition of their gut microbiota compared to a control group, suggesting that mindfulness practices can have a beneficial impact on gut health.

Despite the growing understanding of the gut-brain-microbiome axis, researchers face challenges in studying the relationship between mood and the microbiome due to the myriad of factors involved. The complexity of the microbiome and its sensitivity to a wide range of influences, including diet and stress levels, make it difficult to isolate specific effects on mood. However, the accumulating evidence highlights the promising potential of interventions designed to mitigate stress and enhance mental health. These strategies not only positively influence the gut microbiome but also open novel pathways for addressing gastrointestinal and psychiatric disorders, as well as improving overall mood.

“I’m confident that in the near future we will gain a far more clear understanding of how our diet and microbiome influence our mood,” states Dr. Spencer. “As this field of research expands, we will likely see more ‘psychobiotics’, which are targeted microbial therapeutics to improve our gut-brain connection. Dietary and microbial approaches to improve mental health will undoubtedly be part of our toolkit to promote well being.”

What is Fiber and Why is it Important for the Microbiome?

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By Sharon Brock, MEd, MS

Key Takeaways: 

  • Fiber promotes a healthy microbiome by feeding the “good” bacteria in the gastrointestinal tract.
  • Fiber is not broken down by the digestive organs but instead passes through the body to support healthy bowel movements.
  • 95% of Americans are deficient in fiber.
  • 19-38 grams of fiber per day is recommended and should be added to every meal.
  • Fiber is found in plant-based foods, particularly beans, nuts, fruits, and vegetables.
  • Fiber has many health benefits, including reducing risk of cardiovascular disease, type 2 diabetes, and several cancers.

Fiber not only helps us stay regular, but it also supports a healthy gut microbiome, which is crucial for overall health. Studies show that getting enough fiber strengthens the immune system, supports gut health, reduces inflammation and risk for heart disease, stroke, hypertension, obesity, Type 2 diabetes, and several cancers, including colon and breast cancer.

Although the Institute of Medicine recommends consuming 19-38 grams of fiber per day, national surveys show that 95 percent of Americans don’t consume enough fiber in their diets.

“The biggest thing I’ve learned in my nutrition research is that it’s very rare for people to consume sufficient fiber,” says Jessica Hope, Nurse Practitioner, and member of the Stanford Lifestyle Medicine nutrition pillar. “As a country, we aren’t deficient in protein; we are deficient in fiber. We need to spread awareness about this problem.”

What is Fiber, and What Does it Do?

Fiber is a type of carbohydrate that serves as a prebiotic, or food for the “good” bacteria in the gut, promoting a  healthy microbiome. Also, rather than being broken down by digestive organs, fiber passes through the body to support healthy bowel movements. There are two types of fiber: soluble and insoluble.

Soluble Fiber

Soluble fiber dissolves in water and creates a gel-like substance that slows the movement of food through the digestive tract. This slower digestion reduces blood sugar spikes, lowers blood cholesterol, and helps you to feel fuller longer.

Best food sources of soluble fiber include:

  • Legumes: Beans of all kinds, including kidney, black, pinto, white, lima, navy, chickpea; edamame; and peas
  • Oats
  • Tofu
  • Avocado
  • Brussels sprouts
  • Sweet potatoes
  • Broccoli
  • Pumpkin

Insoluble Fiber

Insoluble fiber (aka roughage) is found in the skin and structure of fruits and vegetables—it’s what makes these foods crunchy. Instead of dissolving in water, insoluble fiber attracts water into the stool, making it softer and easier to move through the digestive system. This promotes bowel-movement regularity and prevents constipation and hemorrhoids. Also, since these crunchy foods require more chewing, it takes longer to eat a fiber-rich meal, slowing down digestion and helping with portion control.

Best food sources of insoluble fiber include:

  • Whole wheat products, like 100% wholewheat bread and pasta
  • Oat bran and oatmeal
  • Legumes: Beans of all kinds, including kidney, black, pinto, white, lima, navy, chickpea; edamame; and peas
  • Berries: including blackberries, blueberries, raspberries, strawberries
  • Whole grains, including quinoa, rye, barley, amaranth, brown rice
  • Leafy greens, like kale and spinach
  • Vegetables, like broccoli, okra, radishes
  • Nuts, especially almonds and walnuts
  • Fruits with edible skins, like pears and apples
  • Avocados
  • Sunflower, flax, and chia seeds
  • Potatoes and sweet potatoes
  • Popcorn

Many plant-based foods offer both types of fiber. For example, the flesh of an apple has soluble fiber, and the skin contains insoluble fiber. Legumes and beans also offer both types of fiber.

“Grains don’t carry as many micronutrients as fruits, vegetables, nuts, or seeds,” says Hope. “There’s nothing wrong with getting your fiber from whole grains, they just don’t pack as much of a nutritional punch.”

Health Benefits of Fiber

Consuming adequate amounts of fiber is associated with a host of health benefits and disease prevention, such as:

Cardiovascular Health

Many studies show that beta-glucan, a soluble fiber found in oat and barley foods (such as cereals), reduces the amount of cholesterol in the blood. Lower cholesterol reduces the risks of atherosclerosis (hardening of the arteries) and high blood pressure.

Type 2 Diabetes

Soluble fiber (including beta-glucan) also slows down digestion and reduces sugar absorption into the bloodstream, which lowers overall body weight and the risk for type 2 diabetes.

“Americans eat so few beans compared to other cultures. I think that one of the reasons why we have more heart disease and diabetes in our country is because we don’t have many beans as a traditional part of our diet,” says Hope.

Microbiome Health and Stronger Immune System

The gut microbiome is the community of microorganisms found in the small and large intestine of the digestive tract. Fiber serves as a prebiotic, meaning it feeds the microbiota or “good” bacteria in the large intestine, allowing it to flourish and take up space. This strengthens the immune system in that all bacteria compete for surface area on the gut lining, so if enough space is occupied by “good” bacteria, the “bad” bacteria won’t have room to grow.

Also, when our microbiota consume fiber in the large intestine, they release acids that keep the colon healthy, such as short-chain fatty acid, butyric acid, acetic acid, and propionic acid.

“Microbiota in our gut need to eat just like we do, and when we eat, we are also feeding them. If we don’t feed them enough fiber, they will look around to see what else they can eat. Recent research is pointing toward the possibility that the circumstance referred to as ‘leaky gut’ occurs when microbiota are so starved they begin to eat the lining of our own intestine,” says Hope. “Of all the reasons to eat a lot of fiber, this is the main one for me.”

Anti-inflammation and Anti-Cancer Effects

Research also shows that fiber-rich foods reduce inflammation. One study showed barley increased the amount of butyric acid-producing bacteria in the gut, which is known to suppress excessive inflammatory responses.

Butyric acid has been shown to prevent the development of chronic disease and inhibit tumor cell proliferation, reducing the risk of several cancers, including colon, breast, esophageal, lung, and liver cancer.

Fiber and Longevity

In this epidemiologic study, there is a clear association between fiber consumption and reduction in all-cause mortality. The study shows that among those who consume between 20 to 30 grams of fiber per day, which is the recommended amount, there is a 10 to 20 percent reduction in death from any cause.

Easy Ways to Add Fiber to Your Diet

You can find fiber in most whole or minimally processed plant-based foods, including beans, whole grains, nuts, seeds, fruits, and vegetables.

Easy-to-make, fiber-rich meals:

  • Breakfast – berries with whole grain cereal or oatmeal; avocado toast on whole-grain bread
  • Lunch – leafy-green salad with beans or lentils and avocado
  • Snack – popcorn, whole fruit (eat the skin if possible), nuts (almonds, walnuts)
  • Dinner – quinoa or brown rice with sweet potatoes, broccoli, asparagus, carrots, and/or Brussels sprouts
  • Dessert – pumpkin pie

 Tips to get more fiber in your diet:

  • Eat whole fruits and vegetables instead of juicing—the pulp is the fiber!
  • Swap white rice, pasta, and bread with their brown or 100% wholewheat counterparts.
  • For protein, swap animal products, which contain no fiber, with beans and tofu.
  • If you find fresh produce spoils too quickly, frozen fruits and vegetables are just as nutritious.
  • Fiber supplements (such as ones with psyllium husk) help regulate bowel movements but don’t promote a healthy microbiome because they don’t feed the “good” bacteria. Therefore, it is recommended to consume daily fiber intake from food sources rather than supplements. 

How to Prevent Gas and Bloating from Eating Fiber

The microbiome is comprised of different kinds of bacteria that eat different types of fibrous foods. For example, some bacteria specifically digest black beans, other bacteria digest oats, while other bacteria digest kale. Hope explains that if someone who doesn’t eat black beans frequently suddenly consumes 25 grams of black beans in one day, they won’t have enough black-bean digesting bacteria in their gut, resulting in gas and bloating.

“To prevent gas and bloating, the keys are to drink lots of water and start slow when incorporating more fiber into your diet. The amount of fiber we eat should be just slightly more than the bacteria we already have in our guts are asking for,” says Hope. “People often say things like, ‘black beans don’t agree with me’ but that isn’t the case. They just don’t have enough of the bacteria that digest those beans. Rather than avoid black beans, they can incorporate them slowly into their diets, allowing time for that specific bacteria to multiply.”

Along with starting small to prevent digestive discomfort, Hope suggests experimenting with easy ways to increase the fiber of every single meal to make the habit sustainable. For example, this can be achieved by adding berries to your breakfast, beans to your lunch, and vegetables to your dinner.

According to research, if all Americans increased their fiber intake by 10 grams per day, the reduction in all-cause mortality would be profound, and everyone would be a little bit healthier.

“Along with being essential for your health, fibrous foods are delicious!,” says Hope. “The best way to increase fiber in your diet is to choose foods that you enjoy and add them, little by little, throughout the day. So, if you don’t like beans, perhaps you could start with apples and blueberries, and shop and plan to make these your go-to snack or dessert to develop this healthy habit.”

Considerations When Choosing Supplements

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By Maya Shetty, BS

This blog is part of our Supplements newsletter. If you like this content, sign up to receive our monthly newsletter!

Key Takeaways: 

  • The supplement industry operates with minimal external oversight. Thus, it is critical for consumers to rigorously assess the actual need and proven efficacy of a supplement prior to its use.
  • Most supplement claims lack scientific evidence. Consumers should only consider supplements with solid scientific backing.
  • Opt for brands verified for purity and bioavailability by third-party organizations.
  • Supplements should supplement—not replace—a healthy diet and lifestyle. Emphasize whole foods, physical activity, and balanced health practices over seeking quick fixes.

In an era where every shelf in the wellness aisle promises a solution to your health concerns, supplements stand out as both suspects and saviors. The market is flooded with options: B12 promises to energize you, omega-3 asserts it will curb inflammation, vitamin C and zinc vow to enhance your immunity, and greens powders claim to do everything in between. With so many claims, it’s important to learn how to navigate the supplement world with a critical eye and an informed mind. Stanford Lifestyle Medicine Registered Dietician Marily Oppezzo, PhD, MS, RDN, DipACLM explains how to approach the supplement market and make informed choices for your health.

What is a Dietary Supplement?

Dietary supplements are ingestible products that contain “dietary ingredients” intended to supplement the diet, including vitamins, minerals, herbs, amino acids, fatty acids, live microbials, and protein powders, among many others. Navigating this expansive world requires an understanding of their nature and regulation—or lack thereof. Though many claim to be from natural sources, supplements are essentially laboratory-created entities designed to alter our physiology, underscoring the importance of approaching them with the same level of scrutiny as any medication.

“Just because a supplement is labeled as ‘natural’ or derived from natural sources doesn’t make it healthy, or even safe,” states Dr. Oppezzo. “This is particularly relevant when considering the unnaturally high concentrations [of the nutrient] often found in supplements.”

Despite their widespread use for health-related purposes, dietary supplements are in a regulatory gray area. When it comes to most supplements, the Federal Drug Administration (FDA) is not responsible for ensuring safety, efficacy, purity, or potency. These aspects are managed by the supplement manufacturers themselves (per the Dietary Supplement Health and Education Act of 1994). This means that supplements are exempt from the rigorous testing and validation process mandated for pharmaceuticals, with the FDA stepping in only if enough post-market reports indicate adverse effects. This regulatory gap makes it challenging for consumers to navigate the supplement aisle, emphasizing the importance of thorough evaluation when considering the necessity of a supplement.

Evaluating the Need for a Supplement

While many individuals view supplements as a way to meet their basic nutritional requirements or as a convenient method to optimize health, the reality is that there are relatively few situations where supplements have proven beneficial.

Before taking any supplement, Dr. Oppezzo recommends pausing to consider several key questions: 

  • What is my reason for believing I have a nutritional deficiency or need to take this supplement? Have I spoken to my doctor or taken a blood test to confirm this deficiency? Is there even a test to confirm this?
  • Has a credible source such as a Registered Dietitian or Doctor recommended this to me, or am I influenced by persuasive advertising?
  • What benefits do I expect to gain from taking this supplement? Is there any scientific evidence that this supplement will help me?

Of course, there are circumstances where supplementation can be beneficial. Age, certain medical conditions, and specific lifestyle choices can impact our body’s ability to absorb or synthesize vital nutrients. For instance, older adults might struggle to produce enough vitamin D or B-12 naturally. Athletes engaging in intense training may require additional iron or protein or calories to support their performance levels, while those following vegan or vegetarian diets might need nutrients less common in plant-based foods, such as B-12, omega-3 fatty acids, calcium, and vitamin D.

The most reliable way to determine your nutritional needs is through a professional consultation with a dietitian. This approach allows for a tailored assessment for needs, evaluation of evidence behind supplements you are interested in, and ongoing monitoring to adjust as necessary. 

Assessing Supplement Claims

A significant portion of supplement usage is driven by misconceptions and marketing rather than genuine need. “The wellness industry often races ahead of scientific validation, promoting products with claims that outpace the available evidence,” states Dr. Oppezzo. “They aren’t cutting edge, they are flying out way past the cliff of evidence.”

Addressing this challenge, Dr. Oppezzo encourages consumers to first look for any peer-reviewed studies backing the “need” or the claim of a supplement. Ideally, ask an expert to do this for you. 

While certain supplements, such as vitamin B12, are actually essential nutrients, supported by extensive research, others, like various greens powders and phytochemical blends, lack robust evidence demonstrating their effectiveness throughout the body. The absence of any regulation allows many products to make exaggerated claims without solid proof. As such, many supplement labels contain a hodgepodge of wellness buzzwords, such as “immune booster,” “supports gut health,” and “promotes health aging,” without any science to back up the claims.

Secondly, Dr. Oppezzo urges us to think about its bioavailability—the extent to which it can be absorbed and utilized by the body. Imagine being in the shoes of a supplement itself, considering all the gauntlets it has to pass to do the thing you think it will do and deliver the marketed effects.

Like any ingested substance, supplements are first broken down by the stomach, absorbed in the gut, processed in the liver, incorporated into the bloodstream, and then transported to organs and cells throughout the body. The critical question is whether the supplement can survive this journey in a form that retains its intended benefit and reaches the organ or cell where you think it will do its purported job.

“Let’s put essential vitamins and minerals aside for a moment. Even if there is evidence some supplement or chemical will do something if you dropped it on your cells in a test tube, you don’t know that this translates to your real live body. Further, you don’t even know if the supplement will even succeed at getting inside your body in the first place, let alone maintaining its original ‘active’ structure after it gets inside,” states Dr. Oppezzo.

It’s important to approach supplements with a healthy dose of skepticism and informed judgment. Not all supplements are inherently harmful; some can offer significant benefits when used appropriately. Yet, the decision to incorporate them into your health regimen should be made with careful consideration, guided by credible evidence and, when possible, professional advice. Once identifying the need for a supplement, Dr. Oppezzo recommends the following framework to decide the appropriate brand, dosage, and context for its consumption.

Framework for Choosing a Supplement

 

1. Assess the Safety and Efficacy

When it comes to supplements, third-party testing is a gold standard for ensuring product safety and efficacy. Organizations like ConsumerLab, US Pharmacopeia, and NSF International offer unbiased supplement evaluations, checking for purity, potency, and safety. Consumers can either check these websites to find a trustworthy supplement brand or look for products that bear their certifications. While some manufacturers conduct their own testing, third-party validation is preferable for an impartial review. Also, the supplement landscape is ever-changing, so checking for updates regularly is wise. 

However, it’s important to understand that these organizations do not directly test the efficacy and safety of supplements. This information can only be provided through clinical trials. According to Dr. Oppezzo, these organizations primarily verify the product has the amount that it claims on the bottle, has the supplement in at least a bioavailable form that can get absorbed into your body, and that it is free from high levels of known contaminants. 

2. Dosage Matters

The saying “more is better” is not necessarily true for supplements – or even essential nutrients. Both inadequate and excessive consumption of nutrients can have detrimental effects on health. Although the body is capable of excreting surplus nutrients, fat-soluble vitamins can accumulate in the body to toxic levels if consistently consumed in large amounts. On the other hand, overconsumption of water-soluble vitamins usually leads them to be excreted through urine, which is inefficient, costly, and known as “expensive urine.”

Therefore, it is crucial to adhere to recommended dietary allowances (RDAs) as a starting point and tailor intake based on individual responses. Importantly, consistently exceeding 100 percent of the RDA can result in nutrient imbalances. One example is selenium, a nutrient where both insufficient and excessive intake have been associated with hair loss. Ironically, many products marketed as “hair vitamins” contain selenium levels surpassing the RDA, potentially worsening the very issue they aim to remedy. 

3. Consider the Chemistry

The effectiveness of a supplement can also depend on its chemical form. For example, vitamins that are fat-soluble achieve maximum absorption when consumed simultaneously with a source of fat, such as a small portion of nuts. Additionally, the interaction between nutrients is important; for instance, copper and zinc compete for absorption, and an excess of one can lead to a deficiency in the other. Supplements can also have harmful interactions with certain pharmaceutical medications, so it is important to consult with healthcare providers before starting a new supplement. 

Another important consideration is the degradation of these compounds. For example, there is an oxidation potential of omega-3 and other fatty acid supplements. This means they have the potential to go “rancid” and lose their efficacy, especially when exposed to heat or open air. This vulnerability stems from the unsaturated nature of these fats, which contains double bonds in their molecular structure that are more reactive with oxygen. 

Indications of rancidity include a strong, fishy odor or an unpleasant taste in fatty acid supplements. Additionally, you can look for information on the peroxide value (PV), a common measure of its oxidation potential. This can be found on some supplement labels, as well third-party testing reports, such as NutraSource. Dr. Oppezzo recommends supplements with PV levels less than 8 mEq/kg.

Supplements Are Not Substitutes for a Healthy Diet

Regardless of whether supplements are part of your daily routine, it is important to remember supplements should be seen as supplemental and not taken at the cost of eating whole foods. While they can sometimes fill nutritional gaps, supplements should be distinct from other health behaviors, such as eating well and moving often.

Moreover, focusing on single ingredients or specific nutrients without considering the holistic picture can lead to misconceptions about what supplements can achieve. Just taking vitamin D, for instance, won’t fully address bone health if it’s not combined  with strength training and a calcium-rich diet.  Good health is about the synergy between multiple  health practices and how they complement each other.

“The allure of a quick fix or ‘magic pill’ is an enticing narrative in our fast-paced world, yet it’s important to remember that there is no replacement for a good diet and regular exercise,” states Dr. Oppezzo. “The foundation of healthy aging always has and always will be a direct result of the choices we make on a daily basis, which is what lifestyle medicine is all about.”

 

Vitamin D: Benefits, Sources, Deficiency

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By Maya Shetty, BS

This blog is part of our Supplements newsletter. If you like this content, sign up to receive our monthly newsletter!

Key Takeaways: 

  • Vitamin D affects the health of bones and also plays a role in our muscles, immunity, and prevention of some diseases.
  • The most common form of vitamin D is synthesized in the skin after exposure to sunshine. Vitamin D can also be found in some foods naturally as well as supplements and fortified foods.
  • Vitamin D insufficiency is defined as less than 30 ng per mL of blood. Strive to maintain sufficient vitamin D levels through a balanced diet, sensible sun exposure, and supplementation as needed. 
  • When choosing a vitamin D supplement, D3 is recommended over D2, and should be combined with a fat (such as a handful of almonds or an Omega-3 supplement). You should not take more than 4,000 IU (100 mcg) per day due to the potential for toxicity unless recommended by a medical professional.

In a nation saturated with supplements, vitamin D commands the spotlight as one of the most widely taken across all age groups, second only to multivitamins. 

“Ever since vitamin D deficiency was found to be the root cause of rickets, we have long recognized its role in bone health. Now research is looking at this vitamin as a panacea for numerous ailments, from the common cold, to even cancer,” states Robert Oh, MD, MPH, Chief Wellness Officer of the VA Palo Alto Healthcare System. 

As ongoing research peels back the layers of complexity surrounding this vitamin, the scientific landscape becomes dynamic and subject to rigorous debate.

Where Does Vitamin D Come From?

Vitamin D distinguishes itself from other vitamins due to its unique ability to exist as both a dietary nutrient and as a hormone. Sourced from sunlight exposure, food, and supplements, this fat-soluble vitamin accumulates in the body’s fatty tissues and liver, available to be released as needed.

Sunlight

The primary source of vitamin D is the production that occurs in our skin from cholesterol precursors when exposed to the sun’s ultraviolet-B (UVB) rays, earning its nickname “the sunshine vitamin.” Considering the pivotal role sunlight plays in vitamin D production, daily exposure is beneficial.

Some plants and animals also possess the ability to synthesize vitamin D, contributing to the vitamin’s content in various foods and supplements. In plants, vitamin D is in the form D2 (ergocalciferol), while in animals, including humans, it is in the form D3 (cholecalciferol). Both forms are absorbable by humans; however, there is evidence suggesting that D3 has a more substantial and prolonged impact.

Food

High amounts of vitamin D3 are found in oily fishes such as salmon, mackerel, and sardines, whereas small amounts are found in eggs, red meat, and liver. 

Vitamin D2 is found in specific mushrooms, but its concentrations vary significantly based on exposure to light. Mushrooms, much like our skin, require sunlight for vitamin D production. “Since commercially available mushrooms are typically grown in dark conditions, they contain minimal amounts of vitamin D and organic mushrooms will contain almost none. Exposure to UV light through irradiation, which is not allowed in organic food production, will substantially increase conventional mushroom vitamin D content,” said Rachele Pojednic, PhD, Stanford University nutrition and exercise scientist.

Due to the limited natural food sources of vitamin D, many products, including breakfast cereals, dairy items, and plant-based milks, are fortified with vitamin D2 and D3. For a comprehensive list of vitamin D content in specific foods, refer to the U.S. Department of Agriculture (USDA) list categorized by nutrient content and food name.

Supplements

Vitamin D2 and D3 can be found in supplement form. Due to the potentially higher bioavailability, D3 supplements are typically recommended over D2. 

Dr. Pojednic emphasizes the importance of considering the fat-soluble nature of vitamin D when taking a supplement. “Vitamin D absorption, especially when consumed in concentrated doses, will be significantly enhanced when taken in conjunction with dietary fat, such as a handful of almonds or an omega-3 supplement,” she says.

When determining the appropriate vitamin D supplementation dosage, keep in mind that higher is not better. Toxic levels of vitamin D can arise from excessive supplement intake, a risk not associated with sunlight exposure due to the skin’s ability to self-regulate production. Therefore, Dr. Oh advises consulting with a physician or dietitian before taking high-dosage supplements. “Too much vitamin D can cause health issues, such as too high calcium levels or even kidney damage, so work with your care team if you are taking high doses of vitamin D,” he says.

Health Benefits of Vitamin D

Vitamin D is crucial for human health. While primarily recognized for its role in building strong bones, new findings suggest that this fat-soluble vitamin may exert a broader influence throughout the body. 

“We now know that the majority of organs and tissues in the body possess vitamin D receptors,” states Dr. Pojednic. “This finding suggests vitamin D has effects beyond the skeletal system, sparking considerable research in the potential benefits of vitamin D for multiple health conditions.”

A substantial portion of this research focuses on the effects of vitamin D supplements, rather than dietary and sunlight sources. However, this by no way means the benefits of vitamin D are found solely through supplementation. Additionally, it should be noted that many studies have not compared outcomes in individuals with sufficient versus deficient vitamin D blood levels, which make conclusions from many supplementation studies difficult to interpret.

Bone Health

Vitamin D stands as a key player in sustaining the structural integrity of our skeletal system by facilitating the absorption of calcium and phosphorus—the building blocks of our bones. Through the process of mineralization, these minerals are incorporated into our bones to maintain normal bone density. Inadequate vitamin D levels can result in insufficient mineralization, which can lead to weakened bones and conditions such as osteoporosis, as well as more severe disorders like rickets and osteomalacia. 

While the adverse effects of inadequate vitamin D on bone health are well-established, the evidence concerning the impacts of supplemental vitamin D over-and-above sufficient levels remains inconsistent.

In 2007, the US Agency for Healthcare Research and Quality synthesized the research on vitamin D and determined daily supplementation of vitamin D (≤ 800 IU) with calcium (≥ 500 mg) resulted in small increases in bone mineral density in older adults. 

There is additional evidence that suggests that vitamin D supplementation lowers the risk of fractures in institutionalized older adults (700-800 IU vitamin D) and female navy recruits (800 IU vitamin D and 2000 mg calcium). However, both groups were initially at a high risk of vitamin D deficiency, and their levels were likely insufficient to begin with.

 On the contrary, the largest vitamin D study to date, Vitamin D and Omega-3 Trial (VITAL), showed that daily supplementation of 2000 IU vitamin D did not reduce fracture risk in more than twenty-five thousand midlife and older adults who had sufficient vitamin D levels on average.

The current body of evidence indicates that vitamin D supplementation offers the most significant benefits for individuals with deficiencies. However, for those already meeting their vitamin D requirements, the benefits of additional supplementation are less clear. This suggests the need to approach vitamin D supplementation for bone health as a targeted strategy—aimed at maintaining sufficient levels rather than striving for excessively high, or supramaximal, levels. Such a focused approach ensures supplementation benefits those who need it, without unnecessary excess in those already meeting their vitamin D requirements.

Dr. Pojednic underscores the importance of a proactive approach, stating, “Ensuring sufficient intake of vitamin D and calcium serves as a foundational preventive measure to mitigate bone mineral loss and reduce the risk of osteoporosis later in life.” This strategy is particularly crucial early in life, as the foundation for peak bone mass, particularly for women, is established in our twenties. By achieving and maintaining optimal levels of vitamin D and calcium from a young age, individuals can maximize their bone strength and preserve it as they age.

Muscle Health

Our muscles need vitamin D to function and develop properly. Studies have established a correlation between deficient vitamin D levels and muscle weakness, pain, and atrophy. While the precise molecular mechanisms of vitamin D’s influence on skeletal muscle necessitate further investigation, cell culture studies indicate that vitamin D administration can alter cell pathways related to muscle contraction, cell proliferation, differentiation, growth, and inflammation.

An increasing body of research suggests a positive impact of high and low vitamin D supplementation on physical performance and injury prevention, particularly in vitamin D deficient adults and athletes. Research has identified a negative correlation between blood levels of vitamin D and biomarkers of muscle damage and inflammation, as well as number of injuries. 

“These findings indicate the potential of vitamin D as a supplement for aiding recovery in injured or overtrained athletes,” states Dr. Pojednic. “However, further research is required to determine the optimal dosages and interventions for effective recovery.”

It has also been hypothesized that vitamin D may reduce the risk of falls in older adults by enhancing muscle strength and coordination, thus improving balance and postural sway. An analysis of multiple studies indicates that daily vitamin D supplementation may decrease the risk of falls in older adults with low vitamin D levels. However, this protective effect was not observed in individuals with sufficient vitamin D levels, a conclusion supported by the VITAL trial, which administered 2,000 IU of vitamin D daily.

The current evidence regarding vitamin D and muscle health suggests that the benefits of supplemental vitamin D are, again, primarily observed in individuals deficient in the vitamin, mirroring patterns observed in bone health. However, it may also have some benefit for athletes and others struggling with muscle damage and recovery. Overall, more research is needed to understand the optimal level of vitamin D for muscle health and determine whether these levels exceed what is required for bone health.

Immune Function

Vitamin D plays a crucial role in immune health, demonstrating various effects on inflammation, autoimmune diseases, and infection rates. The VITAL study revealed that healthy individuals taking vitamin D (2,000 IU per day) were less likely to develop autoimmune diseases such as rheumatoid arthritis and psoriasis, with a 22 percent reduction in incidence over the five-year supplementation period. However, these protective effects were no longer evident after participants discontinued the vitamin D supplement. This implies that vitamin D needs to be consistently taken for long-term prevention.

In the context of respiratory health, a comprehensive meta-analysis demonstrated that daily or weekly vitamin D supplementation lowers the risk of upper respiratory tract infections, especially in very deficient individuals. During the COVID-19 pandemic, studies revealed that low serum levels are associated with a higher risk of COVID-19 infection.

These findings underscore the importance of maintaining optimal vitamin D levels for immune health and the long-term prevention of autoimmune and respiratory diseases. “Similar to muscle and bone health, supplemental vitamin D has the most consistent benefits among those with deficient levels at baseline,” states Dr. Oh. “However, the new findings suggest supplemental vitamin D may reduce autoimmune disease risk even in individuals with already sufficient vitamin D levels.” Therefore, further research is warranted to identify the optimal vitamin D level for sustaining long-term immune health.

Diabetes

Research has consistently found an inverse relationship between vitamin D blood levels and diabetes risk. Vitamin D deficiency may influence key biochemical pathways involved in the development of prediabetes and diabetes, impacting beta cell function in the pancreas and contributing to inflammation.

In a noteworthy observation from the Nurses Health study, women who regularly consumed higher daily doses of vitamin D (>800 IU) and calcium supplements (>1,200 mg) experienced a remarkable 33 percent lower risk of Type 2 Diabetes compared to those with lower doses (400 IU vitamin D, <600 mg Calcium).

Further evidence comes from randomized control trials, which have shown that the benefits of vitamin D supplementation are most pronounced in individuals with low levels of this nutrient. In a randomized clinical trial involving 2,000 adults with prediabetes, participants received daily high doses of vitamin D (4,000 IU) over two years. The study discovered a significant risk reduction for diabetes among those with severely low vitamin D levels. However, this beneficial effect was not observed in participants who already had sufficient levels of vitamin D.

Cancer and All-Cause Mortality

Epidemiological studies have revealed a connection between insufficient vitamin D levels and an increased risk of cancer and all-cause mortality, prompting significant research into the potential role of vitamin D in cancer prevention and overall longevity.

Laboratory studies showcase vitamin D’s ability to inhibit cancer cell growth, while epidemiologic investigations suggest that inadequate vitamin D levels correlate with a 30 to 50 percent increased risk of incident colon, prostate, and breast cancer, along with elevated mortality from these cancers. Despite these findings, clinical evidence remains mixed. The large-scale VITAL study reported a reduction in cancer-related deaths over five years of daily vitamin D supplementation (2,000 IU), but not a decrease in the risk of developing cancer. However, a recently published secondary analysis of the trial data revealed that participants taking the vitamin D supplement had a 20 percent lower likelihood of developing advanced cancer, defined as metastatic or fatal.

A review of several clinical trials further substantiated the link between low vitamin D levels and risk of mortality, more broadly showing a seven percent reduction in all-cause mortality with daily vitamin D supplementation (median dose 800 IU).

Many unknowns continue to surround vitamin D and its relation to cancer risk and overall mortality. “Significantly more research is needed to determine if low vitamin D levels are a risk factor for cancer and whether supplementation can impact overall longevity,” states Dr. Oh. “Nevertheless, the present data does suggest that individuals at risk for cancer may consider supplementing with vitamin D.”

How Much Vitamin D Do I Need?

There is controversy over the levels of vitamin D considered to be sufficient; however, it is widely acknowledged that 25-OH vitamin D levels below 30 ng per mL of blood (50 nmol/L) are insufficient to maintain bone health. 

Optimal levels of vitamin D vary among individuals based on factors such as age, race, metabolic differences, and physiological condition. Adding complexity to this understanding, Dr. Pojednic emphasizes that most vitamin D recommendations are based solely on bone health, and levels required to support other tissues may vary. As such, there is no universally accepted optimal vitamin D level for overall health.

Dr. Oh recommends optimizing natural sources of vitamin D first, such as averaging about 30 minutes in the sun most days, and including a few servings of vitamin D-rich foods in their diet. 

Dr. Pojednic adds that achieving these levels does not need to be a daily practice. “Since vitamin D is a fat-soluble vitamin, our fat cells can store excess for weeks. Therefore, it is more important to consider average sunlight exposure and vitamin D consumption rather than focusing on daily intakes,” she says.

Because vitamin D is stored in fat cells, excessive doses can build up to toxic levels, therefore taking high doses of vitamin D (i.e. more than 4,000 IU per day)  can be dangerous and should be avoided. Symptoms of vitamin D toxicity include weight loss, irregular heart beat, hardening of blood vessels and tissues due to increased blood levels of calcium, potentially leading to damage of the heart and kidneys.

Common Risk Factors for Vitamin D Deficiency

Although it seems easy to absorb 30 minutes of sunlight per day , vitamin D deficiency is common in the US. There are many factors to explain this, including limited geographical location, time outdoors, age-related changes, skin color, restrictive diets, and certain medical conditions. Those affected by these factors may need supplementation to ensure they meet their body’s vitamin D requirements.

1. Sun exposure

During the winter months, people who live in areas above 37 degrees north latitude, which includes cities such as San Francisco, Seattle, Denver, St. Louis, Philadelphia, New York, Boston, and Chicago, do not receive sufficient UVB exposure to produce the necessary amount of vitamin D.

“Vitamin D synthesis in our bodies occurs only at specific wavelengths,” explains Dr. Pojednic. “Thus, geographical location is an essential factor in determining the best way to maintain your vitamin D levels.”

Even people living in sunny areas can experience deficiency related to sun exposure. By spending significant time indoors or consistently wearing clothing that covers most of the body, our skin will not receive necessary exposure for optimal vitamin D synthesis. Moreover, while many believe they get sufficient sunlight through car or office windows, most windows filter out the UVB rays necessary for synthesis. 

Of course, there are many concerns surrounding direct sun exposure, most notably skin cancer. Using sunscreen and limiting sun exposure are still very important measures to protect the skin. While the role of sunscreen in contributing to low vitamin D levels is subject to debate, evidence indicates that the typical use of sunscreen does not significantly impact the body’s ability to produce vitamin D. This means that for most individuals, wearing sunscreen during exposure to sunlight still allows for the synthesis of vitamin D.

2. Age

The skin’s ability to produce vitamin D diminishes significantly with age, declining at an estimated rate of 13 percent per decade of life. Additionally, as we age, our body becomes less efficient in absorbing and utilizing vitamin D.

3. Skin color

Individuals with darker skin often exhibit lower blood levels of vitamin D likely due to the pigment melanin acting as a natural shade, reducing the production of vitamin D. Consequently, low vitamin D levels are particularly prevalent among Americans with darker skin tones. 

4. Diet

Individuals who cannot tolerate or choose not to consume milk, eggs, and fish, such as those with lactose intolerance or those adhering to a vegan diet, face an elevated risk of vitamin D deficiency. “The exclusion of these food sources, which are rich in vitamin D, makes it challenging for individuals in these groups to obtain sufficient levels of this nutrient from food alone,” states Dr. Pojednic.

5. Certain medical conditions

Individuals with inflammatory bowel diseases, such as ulcerative colitis, Crohn’s disease, celiac disease, and chronic pancreatitis may encounter difficulties in maintaining optimal vitamin D levels. This is because the absorption of vitamin D, a fat-soluble vitamin, is contingent on the digestive tract’s ability to absorb dietary fat, and inflammatory conditions within the tract can impede this process. Additionally, certain liver and kidney conditions may impair the metabolism and utilization of vitamin D within the body.

“Signs that your body may need more vitamin D than it is currently getting include bone pain, especially of your chest, shins and even overall chronic pain. For athletes, any bone stress injury like shin splints and poor healing stress fractures may indicate a vitamin D deficiency,” states Dr. Oh. “Finally if you have muscular weakness or pain, especially of your upper legs it would be reasonable to check your vitamin D levels with a blood test.”

Supplements for Healthy Aging

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By Matthew Kaufman, MD

This blog is part of our Supplements newsletter. If you like this content, sign up to receive our monthly newsletter!

Key Takeaways:

Here are a few supplements that our health professionals recommend for healthy aging for individuals in midlife and beyond:

  • Creatine – To maintain and build muscle mass and potentially improve cognitive performance.
  • Vitamin D – To promote muscle and bone strength. 
  • Magnesium – To promote restful sleep and brain health.
  • B12 and B9 (folate) – To promote brain health. (B12 is particularly recommended for vegans since it is primarily found in animal products).
  • Multivitamin that is FDA-regulated or third-party tested. Unregulated supplements may not contain the active ingredients to live up to their advertised claims and may contain harmful ingredients.

As we age, taking too many supplements may be taxing to our liver and kidneys, so it’s best to screen to assess where we are deficient and supplement as needed.

Lifestyle choices are most important for maintaining good health as we age, and supplements do not replace a healthy diet and daily exercise.

As a Physical Medicine and Rehabilitation resident, my patients often ask me, “What supplements should I take as I get older?” While it is a complicated question without a clear answer, it’s important to consider. 

Rather than investigating how a supplement affects the entire body as we age, researchers study how supplements impact specific aspects of health, such as sleep, muscle mass, and brain health. However, we all know that we don’t age in only one domain–the aging process affects many parts of the body. Therefore, there are multiple supplements to consider, and which supplement you take depends on your individual goals.

So, whenever I am posed with this question, I always respond with these two questions: 

1) What are your goals regarding aging? Is it just a longer lifespan, or do you also want to feel good in your 70s and 80s and maintain high-quality interactions with people and places? 

2) What aging concerns do you want to address or avoid? Some examples include optimizing your bones and muscles for sustained athletic ability, brain health and cognition performance, and your ability to have restful sleep on a consistent basis.

Which Supplements Should I Take for Healthy Aging?

Supplements to Maintain Muscle Mass and Bone Strength

As we age, the most important things we can do to maintain muscle and bone strength are resistance training at least twice weekly and consume adequate protein, especially from food (both plant and animal sources). Without these two things in place, supplements alone have not been shown to be helpful. 

Regarding protein, I recommend consuming 1.2 – 1.6 grams per kg of body weight per day. This translates to approximately 0.65 grams of protein multiplied by your body weight in pounds, to be consumed evenly over three to four meals per day. 

To maintain and build muscle mass as we age, I also recommend creatine. Consuming between 5 – 25 grams of creatine per day (either as a supplement or in food) has been shown to increase strength and muscle protein synthesis, and maintain lean body mass.

Vitamin D supplementation also has substantial evidence showing improvements in muscle and bone strength in older adults.

Supplements for Brain Health and Cognitive Performance

Some studies show that vitamin D may improve brain health and cognitive performance. Also, magnesium and higher doses of creatine have emerging evidence suggesting they could also be helpful. B vitamins like B6, B12, and B9 (folate) have also been shown to help with cognition prior to diagnosis of mild cognitive impairment and Alzheimer’s Disease.

Many people take omega-3 supplements intending to improve cognition; however, the data is not as strong as many people suspect. Some studies suggest that these supplements are effective, and some don’t. Most experts believe that getting omega-3s from food (such as fatty fish, walnuts, and chia seeds) is preferable to getting them from a supplement in that they are better absorbed in the body. For my patients, I recommend consuming omega-3s by eating more salmon and enjoying a low-inflammatory diet, such as the Mediterranean diet.

Supplements for Sleep

There is not currently a supplement that the American Academy of Sleep would recommend, however, melatonin is the most popular sleep supplement. If you find melatonin helpful, it’s important to use it at the minimum effective dose to prevent circadian rhythm shifts. There is also recent evidence that magnesium is helpful for sleep.

Lifespan vs. Healthspan

 Lifespan is the number of years we are alive, whereas healthspan is how many of those years we feel good (physically and mentally) and are healthy enough to live independently and free from debilitating diseases. 

Although there is no magic pill for a longer life, these supplements may improve your healthspan by increasing your levels of functioning and slowing the progression of chronic conditions. Healthy aging is not only about preventing illness or falls; it also encompasses the ability to engage in activities we enjoy, spend quality time with people we love, and maintain a sense of purpose and excitement as an older adult. 

When choosing a supplement, it is crucial to remember that the FDA does not regulate most supplements. Therefore, there is minimal oversight regarding the ingredients in these supplements and whether they live up to their advertised claims. Without regulation, some supplements don’t contain the active ingredient, and they may even contain ingredients that are harmful, such as heavy metals, not listed on the bottle. Therefore, it is essential to go with supplements that are third-party tested or recommended by health professionals you trust and not just rely on advertising.  

Lastly, it is most important to recognize that supplements cannot replace a poor diet or lack of exercise. We must take supplements in the context of other healthy lifestyle choices, such as adequate nutrition, sleep, exercise, and working with a medical professional to treat any medical conditions. 

Supplements for Elite Athletic Recovery

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By Caitlin Aguirre, Adrian Vallejo, Matthew Kaufman, MD

This blog is part of our Supplements newsletter. If you like this content, sign up to receive our monthly newsletter!

Key Takeaways:

  • It is recommended to consult with a medical professional before taking the supplements listed in this blog.
  • Branched Chain Amino Acids stand out as a well-supported supplement for athletic recovery, aiding in faster physical recovery, decreased fatigue perception, and maintenance of lean mass. Recommended dosages range from 10 – 30 grams per day.
  • L-theanine shows promise in mental recovery post-exercise, with suggested doses ranging from 50 – 200 mg per day. 
  • N-acetylcysteine’s role in reducing perceived muscle soreness remains uncertain, with doses of 1200 – 1800 mg per day utilized for supplementation within existing studies.
  • Turmeric shows promise in alleviating muscle soreness at doses ranging from 1.5 – 5 grams of turmeric extract daily, although research is conflicting. Supplementing with piperine (black pepper) may enhance its effectiveness.
  • Ashwagandha holds the potential to reduce muscle soreness and improve athletic and mental recovery at a dose of 600 mg daily. While research on its effects is limited, current evidence suggests it’s generally safe for supplementation.

For high-performance athletes, achieving peak performance is not solely a result of pushing one’s physical limits. Even the best competitors experience fatigue, musculoskeletal pains, exercise-induced muscle dysfunction (EIMD), and delayed-onset muscle soreness (DOMS) that may impact their ability to sustain maximal training efforts and combat injury. In response to these physical ailments, often a sign of our bodies adapting to higher training loads, high-performance athletes have mastered the practice of athletic recovery.

The principles of athletic recovery can be thought of as a pyramid having a base of quality sleep, balanced nutrition, and hydration. These elements are the foundation upon which adapting to the demands of intense training is built. However, as committed athletes refine their sleep hygiene, prepare macro-friendly meals, and hydrate appropriately, they often look to ascend this metaphorical “athletic recovery pyramid” by utilizing nutritional supplements to gain an edge over their competitors. Previous literature has estimated that 40 – 100 percent of trained athletes have employed nutrient supplementation, depending on the definitions of trained athletes and supplementation.

In this blog post, we’ll explore the role of popular anti-inflammatory and antioxidant nutritional supplements, including BCAA’s, L-theanine (LTE), N-acetylcysteine (NAC), Turmeric, and Ashwagandha, and what role they may play in athletic recovery.

What are Branched Chain Amino Acids (BCAAs)?

BCAAs are a specific class of amino acids that have branched side chains. These include amino acids like leucine, isoleucine, and valine. Studies suggest that BCAAs are among the most commonly used supplements in trained athletes. These essential amino acids are broken down for fuel during exercise, and supplementation has been thought to provide substrate for anabolic (muscle-building) processes to prolong energy sources and protect against muscle damage and fatigue. Rather than a supplement, you may also consume BCAAs by eating foods high in leucine, such as salmon, chicken, cottage cheese, eggs, nuts, lentils, and beans.

Potential Benefits of BCAAs for Athletic Recovery

Our Recommendations

BCAAs are a supplement well supported by scientific literature that can shorten recovery time and decrease perceptions of fatigue. As an athlete, this may maximize athletic results by supporting the ability to continue long training sessions and return to sport quicker!

Dosing

Studies have shown positive outcomes with BCAA supplementation ranging from 0.087 – 0.22 grams per kg of body weight per day for at least eight days. Positive effects were also shown when the athlete took 20 grams one hour prior to exercise. While there’s no apparent consensus on the optimal dosing strategy, studies show that taking between 10 – 30 grams per day had no noted ill effects.

What is L-theanine (LTE)?

LTE is a non-proteinogenic amino acid that is structurally similar to glutamate. It is a primary component of the Camellia Sinensis plant, which is used to make green tea, and can also be found in smaller quantities in other foods, such as mushrooms, apples, and red wine.

Potential Benefits of LTE for Athletic Recovery

Our Recommendations

Since mental restoration following strenuous training or competition is vital for preventing burnout and enabling athletes to maintain a consistent level of high-intensity training, we recommend a supplement that provides mental recovery. Current evidence shows that LTE has the potential to aid mental recovery, however, further studies on larger sample sizes of athletes may be necessary for a comprehensive recommendation. 

Dosing

Although there is no clear agreement regarding the best dosing strategy for LTE, the studies examined in this review have demonstrated physiologic benefits with doses ranging from 50 – 200 mg per day. Within this range, LTE is considered safe for consumption and has demonstrated no toxic effects in both human and rodent studies.

What is N-acetylcysteine (NAC)?

NAC is a synthetic derivative of the naturally occurring amino acid L-cysteine. In the body, L-cysteine and NAC have direct antioxidative properties and serve as precursors to glutathione (GSH), another powerful antioxidant that prevents excessive molecular damage.

Potential Benefits of NAC for Athletic Recovery

  • May reduce perceived muscle soreness – Numerous studies evaluating the effects of NAC supplementation have shown mixed outcomes regarding the benefits of its antioxidative properties and ability to reduce muscle soreness.

Our Recommendations

Further investigations are necessary before clear conclusions can be drawn about whether NAC supplementation improves athletic recovery by decreasing perceived muscle soreness. 

Dosing

While there is no standardized dosing strategy for NAC supplementation, existing studies evaluated doses between 1200 – 1800 mg per day, with a loading period of at least three days. It’s important to note that exceeding 70 mg per kg of body weight may lead to negative side effects, including gastrointestinal upset, so it’s essential to monitor dosage and potential reactions carefully.

What is Turmeric?

Turmeric, Curcuma longa, is a commonly used medicinal herb that contains curcuminoids, including curcumin. Curcumin has been shown to have antioxidant effects and is associated with pain reduction, anti-inflammation, and chronic disease prevention and treatment.

Potential Benefits of Turmeric for  Athletic Recovery

  • May reduce perception of muscle soreness – Despite conflicting literature, numerous studies evaluating the effect of turmeric on whole and lower-body soreness and single-leg squat pain scores have found that its supplementation significantly reduced measures of muscle soreness. However, one recent meta-analysis found no significant effects on exercise-induced muscle damage or delayed onset muscle soreness. 
  • Taking piperine (black pepper) along with turmeric has been shown to potentially increase its bioavailability and may increase the efficacy of this supplement.

Our Recommendations

According to the literature, turmeric, or curcumin, seems to be a safe supplement for potentially reducing perceived muscle soreness following exercise. However, further study is needed to confirm the extent of turmeric’s efficacy due to the presence of conflicting research. It’s worth noting that simultaneously supplementing with piperine (black pepper) may positively influence its effectiveness.

Dosing

There is no standardized dosing strategy, however, doses ranging from 1.5 – 5 grams of turmeric extract daily, perhaps with piperine (black pepper), may be helpful in exercise recovery. Higher doses of 10 mg and above have been shown to produce mild negative side effects, including headache, diarrhea, yellow stool, and rash. Take caution when consuming higher doses is warranted as the literature on safety and side effects is limited. 

What is Ashwagandha?

Ashwagandha, or Withania somnifera, is an adaptogenic herb commonly used in Ayurvedic medicine. It has gained traction within the fitness community due to some preliminary studies showing an association between the supplement and enhancing muscle strength, muscle endurance, and cardiorespiratory fitness while counteracting chronic fatigue, weakness, nervous exhaustion, and premature aging. The mechanisms by which ashwagandha may improve physical recovery in humans are not well understood but are hypothesized to be at least partially due to antioxidant properties and endocrine effects.

Potential Benefits of Ashwagandha for Athletic Recovery

  • May reduce perception of muscle soreness – Supplementation has been found to decrease one’s perception of muscle soreness after exercise. This effect on muscle soreness is attributed to its antioxidant properties and its hypothesized ability to be converted into testosterone and DHEA, however, further study is needed to elucidate the exact mechanism.
  • May reduce recovery time – While evidence for this effect is minimal, two studies found significant improvement in participants’ perceived athletic recovery experiences. 
  • May promote mental recovery – One study found that supplementation lowered participants’ perception of general stress, fatigue, and lack of energy and improved general well-being scores compared to placebo.

Our Recommendations

The literature on the effects of ashwagandha on athletic recovery is minimal, however, current studies suggest that it is a safe supplement that may reduce one’s perception of muscle soreness and improve athletic and mental recovery following exercise. 

Dosing

There is no standardized dosing strategy, however, studies show that 600 mg of ashwagandha daily may be helpful in exercise recovery. Common side effects may include drowsiness, epigastric discomfort, and loose stools. Less common effects include mild CNS depression, increased thyroxine levels, hallucinations, blurred vision, vertigo, nausea, decreased appetite, constipation, hyperacidity, nasal congestion, dry mouth, hyperactivity, nocturnal cramping, skin rash, and weight gain.