More than five million people in the UK have asthma – 235 million worldwide – and exercise-induced asthma can affect up to 90 per cent of sufferers.

During or after a workout, people with asthma can experience a narrowing of the airways, bringing on unpleasant and sometimes fatal systems such as shortness of breath, wheezing, coughing and a tightening of the chest.

Until recently, the only treatment has been drug therapies that are effective but not curative. But now sports scientists at Nottingham Trent University (NTU), UK, have found that asthma exercisers may have a significant reduction in the inflammation of the airways if they take a prebiotic supplement.

Prebiotic supplement
The small study was based on 10 physically active adults who have asthma and eight other sufferers in a control group.

The 10 participants took a prebiotic supplement, Bimuno-galactooligoosaccharide (B-GOS) for three weeks, while those in the control group took a placebo identical in taste and texture. B-GOS, among with other prebiotics, feeds good bacteria in the gut so that it multiplies and takes over bad bacteria.

After the three weeks, everyone in the study took a hyperventilation test which causes a fall in lung function – an effect which is used to define exercise-induced asthma. Their blood was also taken to study circulating markers of inflammation in the airways.

The results of the study, which were published in the online edition of the British Journal of Nutrition* in August, show that the severity of exercise-induced asthma was significantly reduced in those who took the B-GOS supplement. There was also a significant reduction in the blood markers of airway inflammation. In some cases the supplement “completely abolished” the increase in some markers usually associated with airway constriction following exercise.

What the results mean
Given the small study size, the limitations of the research are obvious and greater sample sizes would be a key requirement in the future. That said, the findings provide further evidence of the important role that microbes living in the gut can play in health and disease.

Dr Neil Williams, a lecturer in exercise physiology and nutrition at NTU, and the lead researcher on the study, says: “Our study shows that this particular prebiotic could be used as a potential additional therapy for exercise-induced asthma.

“We’re only just starting to understand the role the gut microbiome plays in health and disease, and it’s becoming increasingly recognised that microbes in the gut can have a substantial influence on immune function and allergies, which is likely to be important in airway disease.

“B-GOS acts to increase the growth and activity of good bacteria in the gut. This in turn may reduce the inflammatory response of the airways in asthma patients to exercise. The level of improvement in lung function that appears after the prebiotic is perceivable by the patient and therefore potentially clinically relevant.”

In response to the report, Asthma UK said that prebiotics can be found naturally in a range of foods such as bananas, yoghurts and even baked-beans, which led to reports in the national media of how the latter could potentially prevent an asthma attack. ?

* Williams, N et al. A prebiotic galactooligosaccharide mixture reduces severity of hyperpnoea-induced bronchoconsfriction and markers of airway inflammation. British Journal of Nutrition. August 2016