Whole Grain and Fiber Addition Study

The human gut microbiota is the complex community of bacteria that reside within the human gastrointestinal tract. This community plays an important role in supporting normal immune function and digestion. Disruption of the microbial communities within the gastrointestinal tract, sometimes termed "dysbiosis" is linked to a wide range of human diseases, including obesity, metabolic syndrome, malnutrition, and cancer. Stability of the microbiome is thought to be important for human health, however the factors that drive microbiome community stability are poorly understood. Within the gastrointestinal tract, the microbiota is constantly exposed to complex mixtures of foods and the products of digestion. Importantly, changes in diet have been shown to rapidly induce shifts in microbial community composition. These compositional shifts can also affect microbial production of bioactive metabolites, which may be one mechanism to explain how the microbiome impacts host physiology and disease. Fiber is often considered to be one of the largest contributors to microbial compositional shifts that follow dietary interventions. Fiber resists digestion and persists through the gastrointestinal tract to reach the large intestine where it can be metabolized by bacteria. The end products of this metabolism are the short chain fatty acids (SCFAs), acetate and butyrate, which are often associated with beneficial health outcomes. Fibrous foods are also a source of polyphenols and other phenolic compounds that may be used by microbes in the production of secondary metabolites or freed from the food matrix by microbial enzymes. The purpose of this study is to: 1) to investigate the impact of high fiber, whole grain and bran cereal on microbiome stability, and 2) to explore the microbial contribution to polyphenol metabolism from whole grain in healthy individuals.