Baker's Yeast Beta-Glucan Supplementation Improves Post-Exercise Mucosal Immunity and Reduces Cold/Flu Symptomatic Days in Marathon Runners
National Strength and Conditioning Association Annual Meeting
July 14, 2012
B.K. McFarlin, K.C. Carpenter, & W.L. Breslin. Department of Health and Human Performance, University of Houston, Houston, Texas, USA
Strenuous exercise, such as running a marathon, is known to suppress mucosal immunity for up to 24-h, which can increase the risk of developing an upper respiratory tract infection (URTI). Such infections can result in lost practice time and reduced performance capacity. While many dietary interventions have been used to combat post-exercise immune suppression, most have been ineffective. Recent evidence has suggested that a commercially available form of baker’s yeast β-glucan (BG) may be useful as an immune-booster.
PURPOSE: The purpose of experiment 1 (E1) was to evaluate the efficacy of supplementing with BG to prevent post-marathon immunosupression and reduce the incidence of URTI symptoms. The purpose of experiment 2 (E2) was to determine if BG supplementation could improve post exercise salivary IgA levels (a potential biomarker for mucosal immunity) in a controlled laboratory setting.
METHODS: The investigators were blinded to the supplement conditions until all data was collected and analyzed. In E1, 182 men and women registered to run the 2011 Austin LiveStrong Marathon were recruited to consume either BG (250mg/d) or placebo (rice flour, PL) for 28-days post marathon and track URTI symptoms using questionnaires. In E2, 60 men and women completed 49±6 min of cycling in a hot (37±2°C), humid (45±5% relative humidity) environment. Subjects supplemented with either BG or PL for 10-d prior to each exercise session. Saliva was collected using a salivette placed under the tongue at baseline (BASE), before exercise (PRE), immediately after (POST), and two-hours after (2H) exercise. The salivette was kept in the mouth for 2-min and then frozen (-80°C) until analysis for salivary IgA using a multiplex kit (MagPix). Data for E1 and E2 were analyzed using separate ANOVAs (P<0.05).
RESULTS: In E1, BG supplementation was associated with a 37% reduction in the number of URTI symptom days post-marathon compared to PL (P=0.026). In E2, BG supplementation was associated with an increase in salivary IgA (P=0.048) at 2H compared to PL. CONCLUSION: The combination of reduction in URTI symptoms (E1) and increased salivary IgA levels (E2) indicates that preventing a drop in salivary immunoglobulin may be one potential mechanism by which BG supplementation reduces cold/flu symptoms post exercise. More research is needed to define other possible immunologic pathways by which BG effects health status. To our knowledge the present experiments are the first to document that supplementation with this particular form of BG improves salivary IgA, a potential biomarker for mucosal immunity, in a controlled laboratory environment.
PRACTICAL APPLICATION: Collectively the present findings demonstrate that this form of BG may be a useful nutritional additive for recreational exercisers and endurance athletes who are concerned with limiting their risk of URTI. The fact that this nutritional additive is Generally Recognized As Safe (GRAS) by US FDA and is not banned by any amateur or professional sport further enhances its potential for application.
ACKNOWLEDGEMENT: The BG (Wellmune WGP®) and funding for this investigation was provided by Biothera, the Immune Health Company.