The foods we eat affect the diversity and composition of bacteria in the gut, which in turn affect immune cells. Those gut bugs are healthiest and support strong immunity when their hosts (that’s us) consume plant foods that are high in fibre.
The gastrointestinal tract (GI tract) has two functions in human physiology: digestion and nutrient absorption, as well as the more difficult task of immunological homeostasis (protecting the body from potentially harmful microbes, while inducing tolerogenic responses to innocuous food, commensals and self-antigens).
The GI tract's unique shape helps all of these activities; numerous levels of infolding result in a massive total surface area that allows for maximum nutrition absorption while also hosting the body's biggest number of immune cells.
The organisation and management of mucosal immune responses generated in the GI tract will be the focus of this review.