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. When the stomach and small intestine are unable to digest certain foods. 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.