BAKER’S YEAST BETA-GLUCAN SUPPLEMENTATION IMPROVES POST-EXERCISE MUCOSAL IMMUNITY AND
REDUCES COLD/FLU SYMPTOMATIC DAYS IN MARATHON RUNNERS
B. MCFARLIN
Journal of Strength and Conditioning Research VOLUME 27 | SUPPLEMENT 4 | APRIL 2013 | S78
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 b-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 (250 mg/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 6 min of cycling in a hot (37 6 28C), humid
(45 6 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 (2 H) exercise. The salivette
was kept in the mouth for 2-min and then frozen (2808C)
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 postmarathon
compared to PL (p = 0.026). In E2, BG supplementation
was associated with an increase in salivary IgA (p = 0.048)
at 2 H 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.
