This elegant study looked comprehensively at whether four non-nutritive sweeteners (aspartame, sucralose, stevia, and saccharin) are metabolically inert. Non-nutritive sweeteners (NNS) are used to reduce or replace sugar in various products with the goal of minimizing calories and avoiding glucose spikes in the body. Because many of these NNS are poorly absorbed, they do not provide direct calories for us like sugar, and generally skate through the small intestine unchanged, making their way into the colon. However, instead of just passing out of the body and into the bowl unchanged, this study showed that each of these four NNS have distinct, physiological effects on the microbiome! Some NNSs may be fuel for certain bacteria, while others may stunt the proliferation of other bacteria. The authors suggest a number of possible microbiome alterations-each a starting point for many more future studies to uncover all the details.
Another finding from this study was that two of the sweeteners tested, Saccharin and Sucralose, impaired individual’s oral glucose tolerance test response*. Aspartame and Stevia did not. You might think – oh, this means Diet Cokes make you insulin resistant. Not quite- the participants didn’t eat the sweetener alone, each NNS was paired with glucose, or “carb fillers,” found in the sachets. Also, there was significant individual variability in responses across individuals, so it’s tough to generalize this result.
The authors suggest future studies should look at sugar alcohols and other NNSs used in sugar-free products, as well as extend the period of time that people use the sweeteners, to look for long term effects.
One thing the authors made clear: This study shows exciting new findings, and is a great starting point. Don’t all of sudden toss out your Diet Coke and buy Regular Coke as a result.
*An oral glucose tolerance test is not like a meal or even a food people would typically eat, it is a bottle of pure glucose (75 grams of sugar) and then timed measures of how efficiently the body clears this abnormally high glucose load from the bloodstream.
- Jotham Suez, Yotam Cohen, Rafael Valdés-Mas, Uria Mor, Mally Dori-Bachash, Sara Federici, Niv Zmora, Avner Leshem, Melina Heinemann, Raquel Linevsky, Maya Zur, Rotem Ben-Zeev Brik, Aurelie Bukimer, Shimrit Eliyahu-Miller, Alona Metz, Ruthy Fischbein, Olga Sharov, Sergey Malitsky, Maxim Itkin, Noa Stettner, Alon Harmelin, Hagit Shapiro, Christoph K. Stein-Thoeringer, Eran Segal, Eran Elinav. Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance. Cell, 2022; DOI: 10.1016/j.cell.2022.07.016