Characterizing the Gut Microbiota in Healthy Young Adults

Objective/Background: Trillions of micro-organisms reside in the gastrointestinal tract, and play a critical role in the host’s physiology. Recent evidence has demonstrated that these micro-organisms, referred to collectively as the gut microbiota, are intricately involved in the development of obesity, diabetes and other metabolic diseases. Factors including route of delivery (i.e. vaginal birth vs Caesarean), infant feeding practices (i.e. breastfeeding vs formula feeding), diet (e.g. vegetarian vs. low-fat, high fiber diet vs. Western diet), physical activity, medication use, and smoking influence the gut microbiota and contribute marked variability in microbial composition between individuals, yet little is known about what constitutes a “healthy” gut microbiome. Given the emerging importance of the gut microbiota in human health and disease, the objective of this study is to evaluate the associations between lifestyle factors, metabolic biomarkers, and gut microbiome composition, in order to determine whether one or more patterns of “healthy microbiome composition” exists. In addition, we aim to evaluate the intra-individual reproducibility of gut microbiome composition. Methods: Young adults (18-35 years of age) participate in a study visit where they are instructed to collect a stool and urine sample, and complete a detailed diet history questionnaire, a validated physical activity questionnaire, a lifestyle habits questionnaire, a validated perceived stress questionnaire and validated sleep index. During the visit, participants also undergo anthropometric measurements including height, weight, and waist circumference, and provide a fasting blood sample to evaluate metabolic markers including blood glucose levels, lipid profiles, and inflammatory cytokines. Participants are then asked to record their diet, physical activity, and sleep patterns and are also asked to provide two additional stool samples, over a period of seven days following their study visit. Results: Data collection is currently in progress. To date, we have screened 65 volunteers and have enrolled 11 participants (9 male, 2 female, mean age 22.09). Conclusions: In investigating the reproducibility of repeated measures of microbial composition and in determining what constitutes a ‘healthy’ microbiome, our study will provide important data, which will advance the human microbiome field. Findings of this study will enable us to develop rigorously-designed future studies aimed at elucidating the role of the human gut-microbiota in the prevention and treatment of metabolic disease