Eating baked beans or bananas could stave off a potentially fatal asthma attack, suggests new research.
A study shows the risk of suffering an asthma attack after exercise is dramatically reduced by natural plant fibres called prebiotics - also found in yoghurt.
They boost the good bacteria in the gut, providing further evidence of the important role microbes living in the intestines can play in health and disease.
Consumption of a prebiotic supplement resulted in significant improvements in the severity of exercise-induced asthma in physically active sufferers.
After a work-out people with asthma sometimes experience a reduction in their lung function as a result of airway constriction.
That was greatly reduced following three weeks of the course - along with a significant reduction in the inflammation of the airways observed during the study.
Exercise-induced asthma involves a narrowing of the airways during or after exercise - leading to unpleasant and sometimes fatal symptoms such as shortness of breath, wheezing, coughing and a tightening of the chest.
More than five million people have asthma in the UK alone - 235 million worldwide - and exercise can affect nine in 10 patients.
In a study of 10 adults with exercise-induced asthma - as well as a control group - the effects of the prebiotic supplement B-GOS (Bimuno-galactooligosaccharide) were compared to a placebo identical in taste and texture.
All the participants took them for three weeks before crossing over onto the alternative supplement.
The prebiotic dramatically cut the severity of attacks after a hyperventilation test which causes the effects of exercise-induced asthma - as well as significantly reducing blood markers of airway inflammation.
It also completely abolished the increase in chemicals associated with airway constriction following exercise.
Dr Neil Williams, said: “Our study shows this particular prebiotic could be used as a potential additional therapy for exercise-induced asthma.
“We are only just starting to understand the role the gut microbiome plays in health and disease, and it is becoming increasingly recognised that microbes living in the gut can have a substantial influence on immune function and allergies which is likely to be important in airway disease.
“The prebiotic acts like a fertiliser to increase the growth of good bacteria in the gut. This in turn may reduce the inflammatory response of the airways in asthma patients to exercise.
“Importantly, the level of improvement in lung function that appears after the prebiotic is perceivable by the patient and therefore potentially clinically relevant.”
Asthma UK said prebiotics are found naturally in a range of foods including baked beans, bananas and yoghurts.
Dr Samantha Walker, Asthma UK’s director of research and policy, said: “Prebiotics can be found naturally in foods such as baked beans, bananas and yoghurt.
“For a long time people have thought they are good for your health but this research has found the benefits could go beyond a healthy tummy and could help some of the 5.4 million people in the UK with asthma.
“Scientists think the bacteria in your gut can affect your immune system and we know the immune system plays a large role in asthma and its symptoms.
“The challenge now is in understanding how the two are related and whether treating your gut can help your lungs too.
“The study gave people supplements rather than changing people’s diets so it’s a bit early to be stocking up on baked beans and other foods containing prebiotics.
“More research is needed but this study shows promise for the future to help people for whom exercise triggers their asthma.
“Every ten seconds in the UK someone is having a potentially life-threatening asthma attack and exercise is a common trigger of these.”
The findings were published in the British Journal of Nutrition.