The gut microbiome, which hosts up to 1000 bacterial species that encode about 5 million genes, perform many of the functions required for host physiology and survival. Most of us are aware that the bacteria in our gut play an important role in digestion. In addition, gut bacteria are known to aid the production of certain vitamins - such as vitamins B and K - and play a major role in immune function. Most studied is how gut microbiota affects an individual's risk of obesity and other metabolic conditions. two thirds of the gut microbiome is unique to each person, and what makes this unique is the food we eat, the air we breathe and other environmental factors. Some studies have even suggested the makeup of the gut microbiome is influenced by genes.