Researchers have found that consuming green vegetables is important to a fully functioning immune system.
They do this by ensuring that immune cells in the gut and the skin known as intra-epithelial lymphocytes (IELs) function properly.
"After feeding otherwise healthy mice a vegetable-poor diet for two to three weeks, I was amazed to see 70 to 80 percent of these protective cells disappeared," said Marc Veldhoen of The Babraham Institute in Cambridge.
Those protective IELs exist as a network beneath the barrier of epithelial cells covering inner and outer body surfaces, where they are important as a first line of defense and in wound repair.
Veldhoen's team found that the numbers of IELs depend on levels of a cell-surface protein called the aryl hydrocarbon receptor (AhR), which can be regulated by dietary ingredients found primarily in cruciferous vegetables.
The new work found that mice fed a synthetic diet lacking this key compound experience a significant reduction in AhR activity and lose IELs.
With reduced numbers of these key immune cells, animals showed lower levels of antimicrobial proteins, heightened immune activation and greater susceptibility to injury.
When the researchers intentionally damaged the intestinal surface in animals that didn't have normal AhR activity, the mice were not as "quick to repair" that damage.
As an immunologist, Veldhoen says he hopes the findings will generate interest in the medical community, noting that some of the characteristics observed in the mice are consistent with those seen in patients with inflammatory bowel disease.
The findings were reported online in the journal Cell, a Cell Press publication, on October 13th.