Korva is a scroll of the internet’s best ideas.
The people who avoided sweeteners
Who got recruited
Most applicants who said they avoided artificial sweeteners turned out to be eating them, since sweeteners are everywhere, and were screened out. The people who remained were a clean slate, with no preexisting exposure to cloud what adding sweeteners would do. They were also people who had gone to painstaking lengths to avoid them, so they likely held a preconceived notion that sweeteners are bad for you.
Blinding limits
The researchers acknowledged that they couldn't blind the study, since someone used to regular sugar can taste that an artificial sweetener is not the same sweet. That leaves open a placebo-like effect on the blood glucose response. The glucose changes showed up with sucralose and saccharin but not with stevia and the others, which argues against a pure belief effect, since belief would be expected to show up across all of them.
Study design and findings
Participants gave themselves oral glucose tolerance tests while wearing continuous glucose monitors, with no oversight of what they ate or did beforehand. Two weeks also leaves room for a transient effect that fades. The study did show that some sweeteners are not inert, and it saw a big increase in butyrate production, presumably from the change in the gut microbiome, which is associated with better insulin sensitivity and inflammation outcomes.
Why do people respond so differently to the same food?
In a 2015 study in Cell, Eran Zeevi, Eran Elinav, and Eran Segal at the Weizmann Institute tracked blood glucose in 800 people with continuous monitors. Identical foods produced very different glucose curves in different people. A model that used gut microbiome composition, along with other data, predicted responses better than counting carbohydrates alone.
What does butyrate do in the body?
Butyrate is a short-chain fatty acid made by gut bacteria fermenting fiber. It fuels the cells lining the colon and helps maintain the gut barrier. In lab and animal studies, it dampens inflammation and improves insulin sensitivity. Higher stool butyrate has been linked to a more diverse microbiome.
How do sucralose and saccharin differ from stevia?
Sucralose and saccharin are synthesized in factories, while stevia sweeteners are extracted from the leaves of the stevia plant. Their molecular structures differ, which means they interact differently with taste receptors and gut bacteria. Saccharin dates to 1879. Sucralose was discovered in 1976 by researchers at Tate and Lyle working with Queen Elizabeth College.
More from Andrew Huberman
