What is the Gut Microbiome? The gastrointestinal microbiome/microbiota or gut microbiome is the microbes that reside in the intestines and can weigh up to 2 kilograms. The microbiome starts at birth from contact with the motherβs vagina and from skin contact in the following three to five days and then builds from the food the infant consumes and the environment they come into contact with. The microbiome stabilises from around the age of three years and evolves with age and food diversity. The microbiome consists of over 1000 species of bacteria which is over 3 million genes, this is 150 times more than the human genome! What makes it so special is approximately 1/3 of the microbiome is common to the general population, however 2/3 ...