Diet high in fibre and vitamin A key to preventing allergies
Eating a diet rich in fibre can actually shape the immune system to reduce allergies to substances such as peanuts, new research shows. The study, published today, suggests that a simple bowl of bran and some dried apricots in the morning could prevent allergies. It also reveals how the immune system works with the good bacteria in the gut to help protect against life-threatening allergic responses.
There is a global allergy epidemic – and Australian children have the highest recorded rate of allergies in the world.
The Monash University-led study, published in the journal Cell Reports, revealed that it may be a lack of fibre in our diets that’s causing this deadly rise in allergies. By determining how this happens, the researchers have suggested potential treatments to prevent, or possibly even reverse food allergies. They suggest that allergy treatments could use probiotics (beneficial bacteria) that recolonize the gut, or prebiotics (healthy foodstuffs) that could work together to prevent or reverse allergies.
The research, performed largely by Jian Tan, a PhD student at the Monash Biomedicine Discovery Institute, found that mice allergic to peanuts were protected against the allergy when fed a high-fibre diet. In particular, the fibre appears to act by reshaping the gut and colon microbiota.
The study revealed that eating a high-fibre diet actually changes the gut microbiota, the bacteria in the gut, to protect against food allergies. The transfer of these ‘good bacteria’ to mice without these bacteria could reduce the symptoms of food allergies. The microbiota in the gut assist the immune system in resisting allergies through the breaking down of fibre into short-chain fatty acids. This opens up a potential route for drug therapy for allergies by delivering short-chain fatty acids as a treatment.
The scientists, from the laboratory of Professor Charles Mackay, further unravelled how a high fibre diet protects against allergies. They found that short-chain fatty acids boosted a particular subset of the immune system called dendritic cells, which control whether an allergic response against a food allergen happens or not. Effectively, increased levels of short-chain fatty acids switch these cells to stop the allergic response, while a lack of fibre may have an opposite effect. These specialised dendritic cells require vitamin A, another factor which can only be obtained through the diet, and is high in vegetables and fruits.
While deficiency of vitamin A in adults is unusual, the researchers suggest that less than ideal levels of vitamin A in addition to short-chain fatty acids, could promote food allergies in infants. This may explain why the highest prevalence of allergies occurs in children and infants. Mr Tan said the study had not only revealed how the immune system fails when a person becomes allergic, but how the immune system can be helped through diet, to prevent or lessen the effects of allergies. He said the next step was to conduct trials with humans to determine how a high-fibre diet can protect against challenges with allergic foodstuffs.