Diet is known to influence composition of the gut microbiota, however, our understanding of the specific changes in microbial composition that occurs with varying dietary patterns is limited. Much of the work has been conducted using food frequency questionnaires to capture dietary intake, but this technique has many inherent problems which negatively influences the veracity of the data captured. One previously reported study used 24 hour recalls and discovered that the relationship between foods and microbial composition was stronger than the relationship between nutrients and microbial composition, but had a small number of subjects. Kable and colleagues conducted a larger study to explore the relationships between diet diversity and composition of intestinal microbiota, and report the results of that study in the March 2022 issue of The Journal of Nutrition.
Subjects (n=343) for the study were a multi-ethnic cohort of healthy adults that was balanced for age, sex, and BMI. Dietary characterizations were performed (2-3 times) using the automated self-administered 24-hour dietary recall (ASA24) questionnaire and a stool sample was collected from each subject. The dietary data were assembled into tree structures that were annotated with average total grams of dry weight, fat, protein, carbohydrate, or fiber in each food reported. K-means clustering allowed groups consuming similar diets to be formed, and the microbial communities present in those groups were compared.
The correlation between alpha diversities of the diet dry weight and gut microbial communities was significant, and improved when dietary carbohydrates or fiber were used. Diets containing higher amounts of carbohydrates derived from cooked grains contributed to higher numbers of Bifidobacterium. Diets providing higher amounts of fiber from fruits (not berries) led to enrichment of Lachnospira. These results led the authors to suggest that application of a tree structure to diet, annotated with carbohydrate, is a robust method to evaluate the impact of diet on composition of the gut microbiota.
Mary E Kable, Elizabeth L Chin, David Storms, Danielle G Lemay, Charles B Stephensen, Tree-Based Analysis of Dietary Diversity Captures Associations Between Fiber Intake and Gut Microbiota Composition in a Healthy US Adult Cohort, The Journal of Nutrition, Volume 152, Issue 3, March 2022, Pages 779–788, https://doi.org/10.1093/jn/nxab430.
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