“We are what we eat”: How diet impacts the gut microbiota in adulthood

The important role of the microbes residing in our gut, collectively called the microbiota, in human health is widely acknowledged. There are numerous factors that have an impact on the microbiota in the gut of which diet is considered a crucial one. In this chapter we highlight our current knowledge on the ecology of the microbiota in adults and how it is affected by diet. We summarize observations from different cross-sectional and intervention studies that focused on the impact of diet on microbiota composition and activity. Special attention is paid to which microbial metabolites can be produced in the gut; how these are affected by different dietary components such as carbohydrates, fat, and proteins; and how these are associated to human health. Finally, we provide recommendations for future intervention studies in order to improve our understanding of the complex interplay between microbes, diet, and ourselves.