The findings, reported in the journal Cell, could help scientists better understand the basis of intestinal disorders such as inflammatory bowel disease (IBD) and may offer new treatment opportunities.
In the new study, researchers were able to prove that leafy greens protect a certain type of immune cell known as intra-epithelial lymphocytes (IELs). IELs play a crucial role in keeping the gut lining healthy and preventing ‘bad’ bacteria from entering the gut while maintaining the balance of ‘good’ bacteria which help us to break down our food.
Researchers studied mice fed a diet containing many vitamins and minerals known to be essential for good health, but which lacked vegetables. Over three weeks the mice lost 70 to 80 per cent of IELs.
The research showed for the first time that mice fed a diet low in vegetables rapidly lose these specialised immune cells lining the intestinal tract, but not other immune cells. The team discovered that IELs depend on chemical signals from the digestive breakdown products of a substance called Indole-3-carbinol, high levels of which are found in vegetables like broccoli and cabbage.
Dr Marc Veldhoen, senior author of the paper who conducted the bulk of the research at the MRC National Institute for Medical Research before moving to the Babraham Institute, said:
“This was surprising, since the new diet contained all other known essential ingredients such as minerals and vitamins. I would have expected that cells at the surface would play some role in the interaction with the outside world, but such a clear cut interaction with the diet was unexpected.
“After feeding otherwise healthy mice a vegetable-poor diet for two to three weeks, I was amazed to see that 70 to 80 per cent of these [protective] cells disappeared.”
“It’s already known to be a good idea to eat your greens. Our results provide a molecular basis for the importance of cruciferous vegetable-derived phyto-nutrients as part of a healthy diet.”
Dr Brigitta Stockinger, Head of Division of Molecular Immunology at the MRC’s National Institute for Medical Research added:
“The food we eat plays a crucial role in influencing our immune system and we have been looking at the intricate biology that determines how cells in our intestines maintain an intrinsic protection against microbes.
“This study in mice is an important step towards increasing our understanding of how environmental signals shape immune responses at barrier sites such as the intestine. Marc Veldhoen’s continuing studies at the Babraham institute will no doubt take this onto the next step.”
Dr Marc Veldhoen added:
“We don’t yet know the implications of this research for humans, but interestingly, epidemiological studies have linked a diet low in fruit and vegetables with an increased risk of IBD. Our results provide a molecular basis for the importance of nutrients from cruciferous vegetables as part of a healthy diet.”
The research was funded by MRC and BBSRC.
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