How Does Caffeine Affect You?

How Does Caffeine Affect You?

It is difficult to predict how and for how long caffeine affects our bodies. Research suggests that caffeine affects everyone differently and our relationship with it could change as we age. A study examining the relationship between chronotype and the effects of caffeine on sleep in Stanford students found early birds had a strong correlation between daytime caffeine use and waking during sleep. Night owls’ sleep seemed to not be affected by their daytime caffeine intake. People in between seemed to experience minor effects. However, this study was exclusive to Stanford students, who are generally a more sleep-deprived population. It is unclear the degree to which this affected the results but is likely a significant confounding variable.

One of our sleep experts, Dr. Jaime Zeitzer, PhD, says , “There is massive variability in how people metabolize caffeine and in many, even a single cup of coffee with breakfast can interfere with sleep. Being aware of how your caffeine consumption personally impacts your sleep is incredibly important.”

By: Carly Mae Smith, BS

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  1. Modeling caffeine concentrations with the Stanford Caffeine Questionnaire: preliminary evidence for an interaction of chronotype with the effects of caffeine on sleep
Coffee & Longer Lives

Coffee & Longer Lives

A team here at Stanford studying inflammation in older adults found an interesting correlation between those that regularly drank caffeinated coffee and those with lower levels of chronic inflammation. The study suggests that regular, moderate coffee intake may protect us from age-related inflammation and diseases. The clinical trial looking at markers of inflammation and age-related diseases found that 89 older subjects who regularly consumed caffeine from coffee experienced suppressed disease-related inflammation.

Before grabbing your next cup of joe, there are a few things are team would like you to keep in mind:

1) Coffee can mask grogginess, but you still need regular, sustained sleep! Coffee at any time of the day could disrupt sleep.

2) Too much sugar in your coffee may negate Some health benefits!

3) Be careful not to drink too much! Caffeine levels vary by coffee type.

4) If you don’t like coffee, try tea! We see many nutritional benefits in black and green tea too!

There are lots of factors to consider when discussing the impact of coffee and caffeine on our lifestyles, and we hope to cover a lot of them in the near future! To learn more about how caffeine may affect people differently, check out our post on caffeine and chronotypes.

By: Carly Mae Smith, BS


  1. Expression of specific inflammasome gene modules stratifies older individuals into two extreme clinical and immunological states
Exercise and Mental Health

Exercise and Mental Health

Suicide is a complex and devastating public health issue that affects millions of people worldwide. Despite advances in mental health treatment and suicide prevention efforts, rates of suicide continue to rise, particularly among vulnerable populations such as those with mental or physical illness. Previous research demonstrated that teens with high sedentary behavior had twice the risk of a suicide attempt vs those with low daily sedentary time. There is growing interest in interventions that may reduce the risk of suicide, including promoting physical activity.

Exercise has been shown to have numerous physical and mental health benefits. But can exercise also help prevent suicidal behaviors? In this systematic review and meta-analysis, researchers explore the potential protective effect of exercise against suicidal ideation, suicide attempts, and death by suicide in people with mental or physical illness. By examining the existing evidence on this topic, we hope to shed light on a promising new avenue for suicide prevention efforts.

The key findings of this systematic review and meta-analysis were that exercise may have a significant protective effect against suicidal behaviors in people with mental or physical illness. The study found that even though people who exercised had thoughts about suicide just as often, the likelihood of acting on those thoughts by attempting to end one’s life was 77% lower among people in exercise interventions compared to control groups. Death by suicide was 36% less likely among exercisers, but this difference did not achieve statistical significance. The randomized controlled trials included in this study were selected through a comprehensive search of multiple databases and were analyzed using established methods for meta-analyses. However, there was a high risk of bias in many studies. Depression was the most common condition in these studies, but people with menopause, breast cancer, sickle cell, and Huntington’s were included in one study each.

Although further research is needed to better understand the mechanisms underlying this effect, and to identify optimal exercise interventions for different populations, these findings suggest that exercise reduces the chance that a person suffering with depression or a medical illness will act on suicidal thoughts. Possible mechanisms include exercise providing relief from distress, improving depression, generating optimism or facilitating social connectedness.

Promoting regular physical activity appears to have important potential as a suicide prevention strategy that could serve us well in an age of growing mental health and suicide crises.

If you are interested in learning more about the connection between lifestyle medicine and mental health, check out a previous post on how physical activity may affect symptoms of depression, anxiety, and psychological distress. Other lifestyle behaviors, such as diet and sleep, may also impact mental health, and this is outlined in detail here.

By: Helena Zhang & Douglas Noordsy, MD

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  1. The effect of exercise on suicidal behaviors: A systematic review and meta-analysis of randomized controlled trials
Navigating the Difficult World of Supplements

Navigating the Difficult World of Supplements

By Matthew Kaufman, MD

When you think about nutritional supplements for athletic performance, you may imagine an advertised “get fit quick!” and a promise to change your whole life. I remember when friends, teammates or a coach would tell me about a supplement, I would often tune it out for a couple of different reasons. First, we must be aware that if it sounds too good to be true it probably is. Second, the supplement industry does not follow the same FDA standards that other drugs or medications have. This means that some of the supplements people buy may not contain adequate levels of different ingredients or may even contain things that might be harmful to your health like mercury or arsenic.


So instead, I decided to investigate these supplements myself and found some interesting research. From my findings, I gathered three big takeaways: (1) Some supplements are safe and rooted in research, while others have mixed evidence for their efficacy, (2) what are considered the most effective supplements surprised me- and may surprise you, and (3) in shopping for supplements, it is difficult to determine how to find the best value.


Most common supplements are safe when used and sourced appropriately. For instance, Creatine, a protein our body naturally uses for quick sources of energy and can be used to improve power in high intensity exercise performance, does not lead to kidney dysfunction when taken as recommended (ie. 5g four times daily, or 0.3g/kg of body weight for 5-7 days as a loading dose and then 3-10g/day for maintenance dose) and does not need to be cycled on and off as previously thought. In fact, vegans and vegetarians may benefit even more from daily creatine supplementation because they do not get as much from their diet. With more and more athletes exploring vegetarian, vegan, and plant-based diets to promote longevity, Creatine supplementation may become more important down the line. With common supplements such as Creatine, Caffeine, B-Alanine, BCAA’s, Citrulline, Arginine and Beet Root Juice, minimal safety concerns have been reported from the thousands of research studies conducted. This means the risk of taking these supplements is overall low, so if you feel inclined to try one for yourself, you can feel safe in doing so after discussing with your healthcare provider. Overall, it is important to understand that the common supplements that people take are well regarded for their safety, and after proper consultation with a medical practitioner, will likely not lead to long term consequences.


There was also a surprising amount of evidence supporting the efficacy of different supplements for sports performance. Caffeine, for example, has robust evidence for improving performance for athletes. Caffeine has been shown to increase power and velocity in strength training and performance in boxers, shot put, rowers and cyclists. On the other hand, while Branched Chain Amino Acids, or BCAAs, are one of the most popular supplements, the actual evidence did not robustly support their use in sports performance. BCAAs are a specific group of amino acids consisting of isoleucine, leucine and valine that are thought to be linked to recovery and prevention of muscle breakdown. International societies have even weighed in with the Australian Institute of Sport giving BCAAs a grade “C”, meaning that the current evidence is not supportive of benefit amongst athletes OR no research has been performed to guide an informed opinion. Dietary Nitrates, like Beet Root Juice, and Caffeine have an “A”, meaning that there is strong evidence for certain situations in sport with evidence-based protocols. For instance, there is strong evidence, that Beet Root Juice supplementation can lead to prolonged high-end effort as well as improved average and max power especially in the endurance athlete. It is important to realize that every supplement may not help sports performance in all domains. Understanding how each supplement can impact your strength, endurance, recovery, and other aspects of exercise and sport is crucial to knowing the appropriate situations where each supplement is warranted.


Finally, my research showed how difficult it can be to purchase the right supplement. When visiting a popular internet marketplace, I had no idea where to start. There were numerous blends of different supplements, with different concentrations and all at different price points. With this immense variation, it is incredibly difficult for any buyer to determine the right product for them.


Here are 5 easy steps I recommend for finding quality supplements that will help you meet your athletic goals:

  • Meet with your healthcare provider to decide if and what supplement is appropriate for you and your goals. Make sure to discuss things like the proper dosage and time course!
  • Check for safety information for your supplement on MedWatch (the FDA reporting site for adverse events and reactions).
  • Check for quality and accuracy of reported ingredients in your supplement at ConsumerLab, US Pharmopecia, and NSF International.
  • Check the price of your supplement across multiple stores and vitamin shops to ensure you find the most cost-effective option.
  • After deciding the proper supplement with your physician, report your experience with them!



From this investigation of sports supplements, it’s clear how important it is that people understand exactly what they are taking, but this is no easy task. Because supplements are not regulated in the same ways as medications, we as consumers must complete the necessary research ourselves. We need to ask ourselves, “What really is in these supplements?” and “What is the impact of the supplement’s ingredients?” The best thing to do would be to talk about your goals with a physician or medical professional who understand these supplements and can recommend a trusted brand or source. Don’t miss the full systematic review, Supplements for Athletic Performance, that will be published in the coming months.

What a 10-Second Balance Test Can (and Can't) Tell Us About Longevity

What a 10-Second Balance Test Can (and Can’t) Tell Us About Longevity

A recent study found that standing on one leg for 10 seconds was independently associated with survival and that those unable to perform this test had double the usual risk of premature death. This relationship is an association and not causal – meaning, the test cannot predict when someone will die. It does, however, highlight the importance of monitoring and maintaining balance as we age. Good balance later in life can lower fall risk and help maintain independence, mobility, functional abilities, and overall quality of life.

According to Corey Rovzar, an expert in balance a postdoctoral fellow at the Stanford Prevention Research Center in the School of Medicine, balance is often overlooked in most people’s exercise regimes and is not regularly included in routine health checks for middle-aged and older adults. This study highlights the importance of monitoring and maintaining balance as you age since balance tends to decline most rapidly beginning in your 60s – and this decline can lead to faulty biomechanics and/or falls. The good news is that you can improve your balance through training! This could be as simple as standing on one leg while you brush your teeth, performing single-leg exercises, or engaging in activities such as tai chi and yoga. Strength training is also important, especially for the lower body, because stronger muscles allow you to have greater stability as you move and to move at an ideal speed. The key to any exercise program is consistency – find something that you enjoy and stick with it!

By: Corey Rovzar, PhD & Maya Shetty, BS

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  1. Successful 10-second one-legged stance performance predicts survival in middle-aged and older individuals
Beneficial Effects of Tea on Longevity

Beneficial Effects of Tea on Longevity

The study analyzed data from 6387 participants and identified three distinct tea consumption trajectories. After a median follow-up of 17.9 years, it was found that high tea consumption was associated with a lower risk of mortality, but this effect was observed only in non-alcohol drinkers. Among current alcohol drinkers, increasing tea consumption was linearly associated with increased mortality. Additionally, the study revealed that alcohol intake masked the protective effect of tea consumption against blood pressure progression.

In conclusion, individuals with a long-term high tea consumption trajectory had a lower risk of all-cause mortality and a slower rate of blood pressure increase. However, the beneficial effects of tea consumption were diminished or even harmful in the presence of alcohol intake.

By: Michael Fredericson, MD

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  1. Alcohol intake masked the protective effects of tea consumption against all-cause mortality and blood pressure progression: Findings from CHNS cohort, 1993–2011
HIIT Exercise May Counteract Heart Disease Progression

HIIT Exercise May Counteract Heart Disease Progression

As we know, exercise is an essential component of a healthy lifestyle and has many benefits from an evolutionary perspective. However, healthcare professionals have debated the type and intensity of exercise most beneficial for individuals with coronary artery disease.

A recent study published in the European Journal of Preventive Cardiology sheds new light on this issue by examining the effects of high-intensity interval training on coronary atheromatous plaques. After selecting patients with stable coronary artery disease who had undergone percutaneous coronary intervention (PCI), patients were randomly assigned to follow high-intensity interval training or current preventive guidelines. The atheroma volume of patients was measured at baseline and after 12 months.

The results indicate that high-intensity interval training can counteract atherosclerotic coronary disease progression by reducing atheroma volume in residual coronary atheromatous plaques following percutaneous coronary intervention (PCI).

The evidence of how high-intensity interval training can effectively reduce atherosclerotic coronary disease progression and improve cardiovascular health has significant implications. First, the possibility of HIIT as an effective way to mitigate atherosclerotic coronary disease progression introduces the idea of incorporating HIIT into patient rehabilitation programs. Moreover, adding HIIT into their lifestyle may improve their quality of life.

Healthcare providers may consider incorporating HIIT into rehabilitation programs for patients with coronary artery disease, and anyone hoping to optimize their heart health may create personal lifestyle goals and add HIIT to their routine.

By: Helena Zhang, BS

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Box Breathing A Calming Technique

Box Breathing: A Calming Technique

The Research Behind Box Breathing

Picture this: you’ve just encountered a stress-inducing event, such as a disapproving email or a tense phone conversation. Almost immediately, you begin to worry, your heart rate quickens, and your breaths become more rapid.

A study published on in Cell Reports Medicine by Yilmaz Balban et al. revealed that participants in controlled breathing groups – box breathing, mindful meditation, and cyclic sighing – experienced notable improvements in problem-solving, peacefulness, and positive thoughts.

On average, those in the controlled breathing groups reported a daily uplift in positive affect of 1.91 points on the Positive and Negative Affect Schedule scale, compared to 1.22 points for the mindfulness meditation group – an increase of roughly one-third.

The Technique

Box breathing consists of a series of four breaths, ideally inhaling and exhaling through the nose. Inhale deeply for 3-10 seconds, then exhale for the same duration. Be sure not to hold your breath when your lungs are empty!

To determine the optimal inhale and exhale duration, take a deep breath, filling your lungs to capacity, and then time how long it takes to empty your lungs as slowly as possible.

If it takes 0-20 seconds, your inhales, exhales, and breath holds should last 3-4 seconds.

If it takes 25-45 seconds, your inhales, exhales, and breath holds should last 5-6 seconds.

If it takes 50-75 seconds, your inhales, exhales, and breath holds should last 8-10 seconds.


The next time you face a stressful situation, remember to take control and simply breathe.

By: Helena Zhang, BS & Bruce Feldstein, MD

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The Role of Physical Activity in Successful Aging

The Role of Physical Activity in Successful Aging

By: Helena Zhang, BS and Marcia Stefanick, PhD

Physical activity is considered of utmost importance in the field of research on successful aging. However, the question of what physical activity should look like throughout one’s lifetime remains. While walking is an excellent way to begin exercising, it may not be sufficient for healthy aging in the long run. Instead, research suggests incorporating a variety of exercise modalities into your routine to improve overall health and well-being throughout life. Resistance training – which involves weights, resistance bands, and body weight exercise – plays an important role in muscle and bone density and cardiovascular health. The value of proprioception in physical activity is also emphasized. Proprioception is the body’s ability to orient and sense its own movement and is important for safe and efficient movement throughout life.

    Balance exercises improve the mind-muscle connection and can help to prevent falls. These exercises include Tai Chi and Yoga, which are low-intensity physical activities that increase cerebral blood flow and involve sustained attention. Furthermore, endurance exercises, such as running or swimming, reduce inflammation, improve cardiovascular health, and can result in healthy gut microbiomes (Clauss et al. 2021 and Estaki et al. 2016). Members of the Stanford Lifestyle Team are currently researching the role of physical activity in successful aging. To learn more about an ongoing physical activity intervention trial for cardiovascular disease prevention keep on reading!

Key Guidelines for Older Adults

For substantial health benefits, adults should at least do either: 150 minutes to 300 minutes a week of moderate-intensity physical activity 75 minutes to 150 minutes a week of vigorous-intensity aerobic physical activity or an equivalent combination of moderate- and vigorous-intensity aerobic activity. With aerobic activity preferably spread throughout the week

Additional health benefits are gained by engaging in physical activity beyond these hours. Adults should also do muscle-strengthening and balance activities on 2 or more days a week.

  • Balance activities can improve the ability to resist forces within or outside of the body that causes falls.
  • Balance training examples include walking heel-to-toe, practicing standing from a sitting position, and using a wobble board. Strengthening muscles of the back, abdomen, and legs also improves balance.


Our Team’s Research

Women’s Health Initiative Strong and Healthy (WHISH): A pragmatic physical activity intervention trial for cardiovascular disease prevention

While national guidelines promote physical activity to prevent cardiovascular disease (CVD), the Women’s Health Initiative Strong and Healthy (WHISH) study is the first randomized control trial to test the effectiveness of increasing physical activity for cardiovascular prevention in older women. The WHISH trial is unique in its scale and study design. 49,333 women aged 68 to 99 were randomly assigned to two groups. While one group received a physical activity program, the other group continued with their usual activities. After 8 years of follow-up, the study aims to compare the heart health of these two groups. For the group that was assigned to the intervention, a multi-component physical activity intervention is being delivered.

Based on intervention goals from the U.S. Department of Health and Human Services, the physical activity program in WHISH aims to increase or maintain aerobic physical activity (primarily walking), decrease sedentary behavior (especially sitting), and increase multicomponent physical activity regarding muscle-strengthening, balance, and flexibility. The intervention is delivered through multiple channels including quarterly (seasonal) WHISHful Actions newsletters, with inserts targeted at 3 participant groups based on lower, middle and higher levels of self-reported physical functioning and physical activity levels, monthly telephone calls and emails with motivational messages, and access to exercise resources on the WHISH website. Crucial to our understanding of CVD prevention in older women, the comprehensive and pragmatic approach of the WHISH study make it a landmark study that will inform policy and future research.

Learn more about the WHISH study here:

WHISH PI: Dr. Marcia L. Stefanick

Dr. Stefanick is a Professor of Medicine, Professor of Obstetrics and Gynecology, and a member of the Lifestyle Medicine Program at Stanford University. Her research focuses on chronic disease prevention in men and women. She is the Principal Investigator of the Women’s Health Initiative Strong and Healthy (WHISH), a large-scale physical activity intervention trial investigating whether moving more and sitting less can reduce risk of heart disease in older women.