Recent research previously reported in Peak Performance has indicated that probiotic supplements (containing ‘healthy’ bacteria that aid the digestive system) may have a favourable effect on immunity, especially in athletes who are undergoing rigorous marathon training. However, new Portuguese research suggests that these effects don’t extend to reducing the allergic response to pollen in runners.

In the study, the researchers examined a number of immune and allergic inflammatory markers in 141 Helsinki Marathon runners, prior to the event. The runners completed extensive questionnaires and were then split into two groups; one received a culture of lactobacillus (probiotic) for the following 12 weeks, while the other was given an inert placebo. Both groups were then monitored in the 3-month run up to the event, which also coincided with the summer pollen season.

The questionnaire findings showed that the prevalence of diagnosed asthma was 4.3% (six out of 139 athletes), allergic rhinitis was 17.3% (24/139), food allergies 5% (7/139) and atopic eczema 4.3% (6/139). Meanwhile, 21% (24/112) of the athletes were also sensitised to birch pollen and asthma or allergy medication was used by 20% (28/139) of the athletes.

Blood tests taken after the marathon showed some marathon-induced immune changes (altered immune cell counts in the blood) in both groups of runners, but the probiotic group fared no better than the controls. Moreover, the probiotic supplementation did not prevent the increase of allergic markers during the pollen season, indicating that any benefits of probiotics on immunity did not extend to allergic responses.

Respir Med 2006; 28 [Epub ahead of print]