Dietary macronutrient intake and the gut microbiome in adults undergoing bariatric surgery

Information linking diet with the gut microbiome in bariatric surgery is limited. This pilot study examined correlations between macronutrient intake and gut microbiome indexes in adults undergoing bariatric surgery. Participants were 29 adults (93% female) undergoing bariatric surgery. Food records were used to estimate daily macronutrient intake. Shotgun sequencing was used in pre- and post-operative stool samples to identify changes in microbial composition. Diversity indices and differential abundance were calculated, and correlations between dietary intake and outcomes were assessed using linear regression and machine learning models. Phyla and genera were statistically correlated with macronutrient intakes, in particular, intake of soluble fiber, insoluble fiber, and dietary glycemic index. Changes in nutrient-related functional gene pathways were linked to change in HEI-2015 scores and in soluble and insoluble fiber intake following bariatric surgery. In this hypothesis-generating study, intakes of specific macronutrients were correlated with several microbial phyla, genera, and nutrient-related functional gene pathways.