Gut Bacteria Fermentation Doesn't Affect Key Hunger Hormones in Men
- Authors
- Charlotte Bayer Christiansen, Simon Veedfald, Bolette Hartmann, Astrid Marie Gauguin, Søren Møller, Thomas Moritz, Sten Madsbad, Jens Juul Holst
- Journal
- The Journal of Clinical Endocrinology & Metabolism
- Year
- 2021
- DOI
- 10.1210/clinem/dgab666
- Study Type
- Human
- Outcome
- Neutral
- Peer Reviewed
- Yes
- Country
- Denmark
- Health Condition
- Metabolic Health
- Body System
- Digestive
TL;DR
This study found that cleaning out the colon reduces fermentation but does not appear to affect the levels of certain gut hormones in the bloodstream when fasting.
Key Finding
Increased fermentation in the colon from lactulose did not change blood levels of GLP-1 and PYY hormones, suggesting that colonic fermentation may not directly control the release of these hormones.
Summary
This study tested whether fermentation (breakdown of food by bacteria) in the colon affects the release of two gut hormones called GLP-1 and PYY. Ten healthy men were given lactulose (a type of sugar that bacteria ferment) or water, and researchers measured both the fermentation activity (using exhaled hydrogen as a marker) and hormone levels in the blood. The researchers found that even when fermentation increased significantly, the levels of these two hormones did not change.
Practical Takeaway
This small human study suggests that simply increasing bacterial fermentation in the colon may not be an effective way to boost GLP-1 and PYY hormones. However, this was a short-term study in young healthy men, so it's unclear whether the findings apply to other populations or longer time periods. More research is needed to understand how diet and gut bacteria actually influence these hormones.
Abstract
Abstract Context The colon houses most of humans’ gut microbiota, which ferments indigestible carbohydrates. The products of fermentation have been proposed to influence the secretion of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) from the many endocrine cells in the colonic epithelium. However, little is known about the colonic contribution to fasting or postprandial plasma levels of L-cell products. Objective To determine the impact of colonic lactulose fermentation on gut peptide secretion and to evaluate whether colonic endocrine secretion contributes to gut hormone concentrations measurable in the fasting state. Methods Ten healthy young men were studied on 3 occasions after an overnight fast. On 2 study days, lactulose (20 g) was given orally and compared to water intake on a third study day. For 1 of the lactulose visits, participants underwent a full colonic evacuation. Over a 6-h study protocol, lactulose fermentation was assessed by measuring exhaled hydrogen, and gut peptide secretion, paracetamol, and short-chain fatty acid levels were measured in plasma. Results Colonic evacuation markedly reduced hydrogen exhalation after lactulose intake (P = 0.013). Our analysis suggests that the colon does not account for the measurable amounts of GLP-1 and PYY present in the circulation during fasting and that fermentation and peptide secretion are not acutely related. Conclusion Whether colonic luminal contents affect colonic L-cell secretion sufficiently to influence circulating concentrations requires further investigation. Colonic evacuation markedly reduced lactulose fermentation, but hormone releases were unchanged in the present study.