Influence of polyphenol-rich diet on exercise-induced immunomodulation in male endurance athletes

Introduction: Stress is associated with increased susceptibility to infection. We investigated if the mechanism involves immunomodulation of dendritic cells and whether this can be inhibited by a polyphenol-rich diet. Methods: Blood samples were taken from a total of 100 male endurance athletes at five time points around a marathon run: four weeks before, during one week before, and immediately, 24hours and 72hours after. Participants were randomized into two double blinded groups. One group received a polyphenol rich beverage during a three week training phase before marathon while the other group received a placebo beverage. Flow cytometric analysis of dendritic cell (DC) counts and subpopulation counts (myeloid, plasmocytoid DCs) was performed. Levels of viral antigen presenting Toll-like-receptor (TLR) 7 mRNA was measured by rt-PCR. Results: Marathon running induced a significant increase of circulating myeloid DCs (0.2 vs. 0.33% of whole blood leukocytes [wbl]; p<0.01) and a sign...