Chili pepper compound capsaicin and gut bacteria in lab tests
What it found
In lab tests, capsaicin changed the mix of gut bacteria and increased butanoic acid in one of two people's gut communities.
The effect differed between the two donors.
What they found
Animal and lab studies
Gut bacteria diversity
In lab tests, capsaicin increased the diversity of the gut bacterial community in both donors, based on two diversity measures. The two donors responded differently on a third measure.
Bacteria types changed
In lab tests, capsaicin changed the amounts of certain bacteria. Some bacteria went up and others went down, but the changes were different for each donor.
Butanoic acid
In lab tests, butanoic acid increased at the end of capsaicin treatment in one donor's community, but decreased in the other donor's community.
Propanoic acid
In lab tests, propanoic acid increased with capsaicin in both donors, but the difference was already present before treatment started.
Metabolites and bacteria
In lab tests, capsaicin reduced the number of significant links between certain bacteria and metabolites compared with untreated controls.
What the authors conclude
“Overall, our results found that CAP significantly altered the gut microbial structure and SCFA levels; however, these changes were donor-dependent.”
Also in their conclusions
- They conclude that capsaicin significantly altered the gut microbial structure and short-chain fatty acid levels, but these changes were donor-dependent.
- They say that the increase in butanoic acid and propanoic acid may explain the beneficial health effects of capsaicin.
- They note that the removal of host tissues in their lab model allows the effects on bacteria alone to be seen.
How it was done
The authors wanted to find out how capsaicin, the compound in chili peppers, affects the gut bacteria, since previous studies in people and mice suggest it may have health benefits but the mechanism is unclear.
They grew gut bacteria from two people's stool samples in lab bioreactors that mimic the large colon. After two weeks of stabilization, they added capsaicin for 14 days and compared it with control reactors.
What it can’t tell you
- This was a lab study using gut bacteria grown outside the body, so it cannot show what happens in people.
- The study used bacteria from only two people, so the results may not apply to everyone.
- The lab model does not include the host's cells or immune system, so it cannot show the full picture of capsaicin's effects in the body.
Who paid
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- Eastern Regional Research Center, USA; Donald Danforth Plant Science Center, USA; US Army Combat Capabilities Development Command Soldier Center, USA
The paper
- Title
- Analysis of the Ability of Capsaicin to Modulate the Human Gut Microbiota In Vitro
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Mahalak KK, Bobokalonov J, Firrman J, et al (2022). Analysis of the Ability of Capsaicin to Modulate the Human Gut Microbiota In Vitro. Nutrients. doi:10.3390/nu14061283Free full textPubMed 35334939DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error