The study, published in The Journal of Nutrition, cross-analyzed information from participants of the American Gut Project. By comparing microbiota populations in stool samples with diet information, researchers were able to determine which foods resulted in more diverse microbiota populations.
“We observed differences ... that corroborate evidence underlining the dietary impact on the gut microbiota and extend previous research by presenting results from a very healthy cohort that may help inform future work aiming to define a ‘healthy’ microbiome,” wrote the researchers from the University of Illinois at Urbana-Champaign and the University of California San Diego.
A total of 432 participants were included for analysis, ranging from 18 to 60 years old. Participants completed the VioScreen food frequency questionnaire and mailed in fecal samples. The food frequency questionnaire was completed for the 90 days prior to mailing in the fecal samples.
The researchers investigated the differences in fecal microbiota composition, cross-referencing with the dietary data. Scores were calculated using the Healthy Eating Index (HEI), which calculates how compliant a person is in following the dietary guideline recommendations. HEI-2015 scores have an inverse relationship with the risk of several health conditions including cardiovascular disease, type 2 diabetes and cancer. Scores were calculated by categorizing 13 elements into two groups: adequacy components, which are encouraged, and moderation components, which are limited. A higher HEI score would be made via a greater consumption of adequacy components and limited consumption of moderation components. Adequacy components include fruit, vegetable, whole grains, protein, dairy, etc. while moderation includes refined grains, added sugars, saturated fats and sodium.
The study divided the participants into two groups after analysis, one (T3) comprised of individuals who closely adhered to the dietary guideline recommendations; and T1, comprised of those who did not adhere to the dietary guidelines and were similar to the general U.S. population. Those who did adhere to dietary guideline recommendations had differentially abundant microbiota taxa, specifically a higher amount of those that metabolize complex plant-based carbohydrates. The researchers hypothesize this could be due to the increased consumption of high fiber foods.
The participants analyzed for the study had an overall high quality diet with a mean HEI-2015 score of 69.5 — in comparison, the average U.S. adult has a score of 56.7. Those with a higher HEI-2015 score showed greater microbiota diversity. Specifically, total vegetables, greens and beans, whole grains, dairy and refined grain component scores had greater microbiota diversity as well.
“These findings also align with the results from the larger American Gut cohort, where adults who consumed >30 different types of plants a week had greater fecal microbiota diversity,” the study noted. “Higher diversity could reflect the effect of different types of fiber within plant foods (fruits, vegetables, legumes, grains, and nuts) on supporting different intestinal microbiota species. Together, these results suggest that dietary patterns with greater vegetables, legumes, whole grains and dairy, and less refined grains are associated with higher fecal microbial diversity in adults.”
Source: Journal of Nutrition
2023, February 22 doi: 10.1016/j.tjnut.2023.02.018
“Diet Quality and the Fecal Microbiota in Adults in the American Gut Project”
Authors: A.D. Baldeon, et al.
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