Fruits, vegetables and whole-grains might be an unlikely treatment for asthma according to animal studies.Tests on mice, published in the journal Nature Medicine, showed that a high-fibre diet could reduce inflammation in the lungs.The extra fibre changed the nutrients being absorbed from the gut, which in turn altered the immune system. The researchers argue the shift to processed foods may explain why more people are developing asthma.The airways are more sensitive to irritation and more likely to become inflamed in people with asthma. It leads to a narrowing of the airways that make it harder to breathe.However, a possible solution may lie in another organ, the gut, and the bacteria which live there.The cells of the human body are vastly outnumbered by the trillions of microbes that live in and on it. There is growing evidence that these bacteria have a significant impact on health.A team at the University of Lausanne in Switzerland showed that the high and low fibre diets altered the types of bacteria living in the guts of the mice.Bacteria, which can munch on soluble fibre, the type found in fruit and vegetables, flourished on the high-fibre diet and they in turn produced more short-chain fatty acids–a type of fat, which is absorbed into the blood.The scientists said these fatty acids acted as signals to the immune system and resulted in the lungs being more resistant to irritation.The opposite happened in low-fibre diets and the mice became more vulnerable to asthma.The report says a diet shift away from fibre in favour of processed foods may be causing rise in asthma.