Washington: If you're constantly fighting off colds, tuck into a big bowl of greens. That's the conclusion of a new study from researchers at the Babraham Institute in Cambridge, where scientists found that green vegetables turn out to be the source of a chemical signal that's important for a fully functioning immune system.

The study, published online in the journal Cell, found that these chemical signals ensure that immune cells in the gut and skin function properly.

Known as intra-epithelial lymphocytes or IELs, the immune cells exist beneath another barrier of cells that cover inner and outer body surfaces and act as a first line of defense and help with wound repair. In lab experiments on mice, researchers found that a diet rich in green vegetables like broccoli or bok choy was found to help regulate this complex immune system, while the same was true of the reverse.

After depriving mice of vegetables for three weeks, researchers said they found that 70 to 80 percent of the protective cells disappeared. The weakened mice showed lower levels of antimicrobial proteins, heightened immune activation and were more vulnerable to injury. When researchers intentionally damaged the intestinal surface, for example, their bodies were slow to recover.

The implications of their findings could help with conditions like inflammatory bowel disease, scientists say, which shares the same characteristics observed in the mice.

Another study published last year in the British Medical Journal also found that eating leafier green vegetables can significantly reduce the risk of developing type 2 diabetes.