Microbiota refers to the population of microorganism (bacteria, viruses and fungi) that inhabit the entire gastrointestinal tract, more particularly the colon whose role is to maintain the integrity of the intestinal mucosa and control the proliferation of pathogenic bacteria. Alteration in the composition of the gut microbiota is called dysbiosis. Dysbiosis redisposes to inflammatory bowe diseases such ulcerative colitis, Crohn disease and indeterminated colitis. The purpose of this literature review is to elucidate the influence of diet on the composition of the gastrointestinal microbiota in the healthy gut and the role of diet in the development of dysbiosis. The "western diet", in particular a low-fiber high/fat carboydrate diet is one factor that can lead to severe dysbiosis. in contrast, "mediterranean diet" and vegetearian diets that includes abundant fruits, vegetables, olive oil and oily fish are known for their anti-inflammatory effects and could prevent dysbiosis and subsequent inflammatory bowel disease.