The immune system is the critical link between gut bacteria and their influence on health and disease. This is a complex relationship and one that science still has a long way to go before we really understand the intricacies between diet, the gut and the body’s immune system.
Gut bacteria are thought to be key in promoting early development of the gut’s mucosal immune system and continue to play an important role later in life.
Full term vaginally born infants are completely colonized with a diverse array of bacterial families by the end of their first year of life. The colonizing bacteria communicate with the gut epithelium and the underlying lymphoid tissue, which results in a functional immune system. By contrast, there may be inadequate bacterial colonization in premature infants, or those born by Caesarian section, as well as less immune cross-talk and an increased incidence of immune-mediated diseases. In adult life, the gut microbiome continues to influence the immune system, and also acts as a protector against invading micro-organisms in the gut. 1
The bi-directional influence of the gut and brain on each other’s functioning further complicates our understanding of how the system as a whole operates.2