The Gut Microbiome

The human gut contains approximately 38 trillion microorganisms—slightly more than human cells. This ecosystem, collectively called the gut microbiome, weighs 2-5 pounds and contains 500-1,000 bacterial species. The dominant phyla are Firmicutes (includes Lactobacillus, Clostridium) and Bacteroidetes (includes Bacteroides, Prevotella). Your microbiome is as unique as your fingerprint, established in the first 2-3 years of life through birth mode (vaginal vs. cesarean), breastfeeding, and early diet. A diverse microbiome is generally associated with better health outcomes; reduced diversity is associated with obesity, inflammatory bowel disease, and autoimmune conditions.