Mice deprived of vegetables in their diet rapidly lost the specialised cells, known as intra-epithelial lymphocytes (IELs).
They also became susceptible to an artificially-induced form of colitis, an inflammatory bowel condition.
IELs on the intestinal surface play a critical role in keeping infections at bay and maintaining a healthy gut.
They help maintain the balance between “good” and “bad” bacteria, and “cull” infected cells that might cause harm.
The new research, published in the journal Cell, showed that certain vegetable compounds stimulate a molecular pathway that affects IEL survival.
One identified chemical is indole-3-carbinol, found in broccoli and other “cruciferous” vegetables. The effect of a low-vegetable diet on IEL levels in the mice surprised scientists.