The Study
Impact of High-Fiber or High-Protein Diet on the Capacity of Human Gut Microbiota To Produce Tryptophan Catabolites
This study was done in a lab jar that mimics a human gut, not in real people. It shows what happens to tiny gut bacteria when you feed them different foods, but we can't say this will happen the same way in actual humans.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Scientists used a lab model of the human gut to see how eating lots of fiber vs. lots of protein changes the chemicals made by gut bacteria.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 57 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1These chemicals may help or hurt your gut health — some are linked to better barrier function and less inflammation, while others are tied to kidney disease.
- 2Fiber made more of 4 good chemicals (IAA, ILA, I3A, IPA); protein made more indole, kynurenine, and oxindole; the back part of the gut made over 10 times more chemicals than the front part, and two chemicals (IPA and oxindole) only showed up there.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Agricultural and Food Chemistry
Year
2023
Authors
Zhan Huang, J. Boekhorst, V. Fogliano, E. Capuano, J. Wells
Related Content
Claims (6)
Legumes contain protein and fiber that human bodies and gut bacteria use together.
When gut bacteria from humans are exposed to a high-fiber diet in a lab system that mimics the colon, they produce more indole-3-acetic acid, indole-3-lactic acid, indole-3-aldehyde, and indole-3-propionic acid than when exposed to a high-protein diet.
In a lab model of the human gut, a diet high in protein leads to higher levels of Proteobacteria in the upper colon and increases the production of the microbial metabolites indole, kynurenine, and oxindole.
In a laboratory model of the human gut, the lower part of the colon generates more than 10 times the amount of tryptophan breakdown products compared to the upper part, and two specific compounds—indole-3-propionic acid and oxindole—are found only in the lower section, showing that microbial activity differs along the length of the colon.
In a lab model of the human gut, a high-protein diet increases the genetic capacity of gut microbes to break down tryptophan into certain metabolites, but the actual levels of these metabolites do not always match the amount of genetic material present.
After stopping a dietary change in a lab model of the human gut, the community of gut microbes did not return to its original state within two weeks, showing that the diet caused lasting changes.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.