Want to protect the body from infection to the intestines? Increase your intake of vitamin A.
According to a study reported in a paper published in the journal Immunity, vitamin A directs a key set of immune cells that protect the intestines.
"We wanted to find the specific role the vitamin plays in the immune system and how it influences the cells and biological processes," said Chang Kim, section head of microbiology and immunology in Purdue University's college of veterinary medicine.
The team found that retinoic acid, a metabolite that comes from digested vitamin A, is necessary for two of the three types of "innate" immune cells that reside in the intestine to find their proper place.
Within our immune system, there are two categories of cells that work together to rid the body of infection.
These are innate immune cells and leukocytes that are fast acting and immediately present to eliminate infection.
Then there are adaptive immune cells (T-cells and B-cells) that arrive later but are more effective at neutralising the infection.
In earlier work, Kim found that vitamin A also regulates the migration of T-cells.
"It is interesting that both innate and adaptive immune cells share a vitamin A-regulated pathway for migration," he added.
Eat more of carrots, sweet potatoes, squah, dried apricots, tuna, mangoes, red pepper, peas and tomatoes-- they are a rich source of vitamin A.