Spicy food and the gut microbiota: explosive health?

It stings, burns, warms the cheeks, titillates the taste buds and even the stomach: but it’s good for your health. Anti-inflammatory, anti-cholesterol, anti-hypertensive, anti-obesity... The virtues of chili peppers seem endless.
These beneficial properties are put down to capsaicin, the compound in red pepper that sets the mouth on fire. Although the spicy effect is hard to miss in terms of taste, the mechanisms involved remain unclear. According to one hypothesis, the consumption of capsaicin may enrich the gut microbiota in bacteria that produce short-chain fatty acids (sidenote: Short chain fatty acids (SCFA) Short chain fatty acids (SCFA) are a source of energy (fuel) for an individual’s cells. They interact with the immune system and are involved in communication between the intestine and the brain. Silva YP, Bernardi A, Frozza RL. The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Front Endocrinol (Lausanne). 2020;11:25. ) , which may be the source of these multiple benefits. 

In vitro study on stool samples

A Chinese-American team carried out an in vitro study to test this hypothesis while avoiding possible interactions between capsaicin and other components of the human body. The researchers collected stool from two healthy individuals, introduced it into a bioreactor mimicking conditions in the colon, and then added either capsaicin or a control solution. After two weeks, the researchers analyzed the composition of the various samples and compared the results with those obtained at the beginning of the study, before the addition of capsaicin or the control solution.

Capsaicin creates a beneficial dysbiosis

Bacterial diversity –which is a sign of good health– increased significantly during the study in the two capsaicin-treated gut microbiota samples, confirming data observed in vivo in various human and mouse studies. The production of some short-chain fatty acids was also altered, but distinctly from one sample to the other: both produced more propenoic acid (known for its role in appetite regulation), but only the first produced more butanoic acid (i.e. butyric acid, which has known anti-inflammatory properties).