Strenuous exercise significantly increases the incidence of upper respiratory tract infections (URTI) caused by transient immune dysfunction. Naturally occurring polyphenolic compounds present in food such as non-alcoholic beer (NAB) have strong anti-oxidant, anti-pathogenic, and anti-inflammatory properties.
PURPOSE: To determine whether the ingestion of non-alcoholic beer polyphenols for three weeks prior to the Munich Marathon would attenuate post-race inflammation and decrease URTI incidence.
METHODS: Healthy male runners (N=277, age 42±9 y) were randomly assigned to 1-1.5 L/day NAB or placebo (PL) beverage (double-blinded design) for three weeks before and two weeks after the Munich Marathon. Blood samples were collected 4- and 1-week pre-race, and immediately-, 24-h-, and 72-h-post-race, and analyzed for inflammation measures (IL-6 and total blood leukocyte counts). URTI rates, assessed by the Wisconsin Upper Respiratory Symptom Survey (WURSS-21), were compared between groups during the 2-week period following the race.
RESULTS: Change in IL-6 was significantly reduced in NAB compared to PL immediately post-race [median (interquartile range): ng/L 23.9 (15.9 - 38.7) ng/L vs. 31.6 (18.5 - 53.3), p = 0.03]. Total blood leukocyte counts were also reduced in NAB versus PL by approximately 20% immediately- and 24-h-post-race (p=0.02). Incidence of URTI was 3.25-fold lower (95%-CI 1.38-7.66) (p=0.007) in NAB compared to PL during the 2-week post-marathon period.
CONCLUSION: Consumption of 1-1.5 L/day non-alcoholic beer for three weeks before and two weeks after marathon competition reduces post-race inflammation and URTI incidence.