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Human gut microbiota, diet and health
It is well established that gut microbiota composition and metabolic capabilities can have far reaching effects on host physiology. Further, diet composition can play a major role in modifying gut microbiota. However, the extent to which beneficial effects of dietary modification are mediated through changes in gut microbiota is largely unknown. The Gut Check study was a cross-sectional investigation of the relationship between gut microbiota, habitual diet, intestinal inflammation and selected health biomarkers. Fifty males and eighty-two females between the ages of 18 and 79 provided photograph assisted three-day food intake records along with stool and blood samples collected immediately following the food records. Diet records were analyzed for selected foods and macro and micronutrient content. Fecal samples were processed for microbiota composition and additionally analyzed for calprotectin levels (a marker of intestinal inflammation). Blood samples were processed for biomarkers of inflammation, insulin sensitivity and endotoxin levels. Despite the recognized limitations associated with assessing dietary intake (even with photo assisted food intake records), strong associations were identified between selected dietary factors and microbiota composition. As an example, we identified a strong positive linear trend (P<0.0001) between tertiles of total milk intake and the relative abundance of the Ruminococcaceae family. A weaker negative association was found between tertiles of milk intake and the Alcaligenaceae family. The relative abundances of the gut microbiota were also associated with parameters of health. Thus the Ruminococcaceae family (members of which have been shown to be higher in controls versus individuals with type 2 diabetes) was negatively associated with diastolic and systolic blood pressure (DBP, SBP) and circulating endotoxin levels. Thus, one would expect that increasing total milk intake would increase Ruminococcaceae and lower blood pressure. Conversely, the relative abundance of the Alcaligenaceae family was negatively associated with BMI, triglycerides, fasting glucose and waist circumference suggesting that increasing milk consumption would adversely affect parameters of metabolic syndrome. Effects associated with calcium intake were minor suggesting a primary effect of dairy intake as opposed to generalized effect of calcium intake. In total, these data emphasize the complicated interactions between diet, gut microbiota composition and health parameters and a need to conduct carefully controlled diet intervention studies.
Keywords:
microbiota, metabolism, intake