The protective effects of a polyphenol-enriched protein powder on exercise-induced susceptibility to virus infection.

Prolonged and intensive exercise induces transient immunosuppression and is associated with an increased risk and severity of infections. The goal of this study was to characterize the antiviral and antibacterial properties of the bioactive metabolites of a blueberry-green tea-polyphenol soy protein complex (PSPC) in the serum of supplemented subjects during a 3-day intensified training period. Long-distance runners, randomly divided into two groups, ingested 40 g/day PSPC or placebo (soy protein and colorings) for 17 days, with a 3-day running period inserted at day 14. Blood serum samples were collected pre-14 days and post-14 days supplementation, and immediately and 14 h after the third day of running. The post-exercise serum from both groups significantly promoted the growth of Escherichia coli and Staphylococcus aureus in culture by 20-70%, but returned to normal levels following recovery. Furthermore, the serum from subjects ingesting PSPC did not display antibacterial properties at any time point. In contrast, there was a significant difference in the ability of serum from PSPC-supplemented versus placebo-supplemented athletes to protect cells in culture from killing by vesicular stomatitis virus following strenuous exercise. In addition, the serum of subjects who ingested PSPC significantly delayed an exercise-induced increase in virus replication. These results indicate that polyphenol complexes containing blueberry and green tea have the potential to protect athletes from virus infections following rigorous exercise.