Cell samples from long-distance runners who ingested 40 grams per day of the polyphenol-enriched protein powder for 17 days were found to resist viral replication, report scientists from the Appalachian State University, the Dole Nutrition Research Laboratory at the North Carolina Research Campus, and North Carolina State University.
However, the serum from the runners did not exhibit any activity against bacteria.
“These results indicate that polyphenol complexes containing blueberry and green tea have the potential to protect athletes from virus infections following rigorous exercise,” they wrote in Phytotherapy Research .
Prolonged strenuous exercise is known to suppress the immune system, with various reports linking such exercise to an increased risk of respiratory tract infections.
Indeed, this is reflected in the dietary supplements and sports nutrition marketplace with products claiming immune support a growing presence in the sector .
The North Carolina-based scientists tested the potential of their blueberry and green tea-enriched protein complex using viral and bacterial challenges to the serum from athletes because it would have been unethical to infect the athletes directly.
In addition, they note that, while the virus used in their study (VSV) was not a human pathogen, it “serves as an effective model system for pathogenic human viruses due to its ability to replicate in cells from a variety of different species.
“This study provides the framework for future studies aimed at determining whether the activity of [polyphenol soy protein complex] in the serum of subjects exerts activity against pathogenic human viruses such as influenza virus, rhinovirus and HSV-1,” they wrote.
The researchers, led by Dr Maryam Ahmed from the Appalachian State University, recruited 31 long-distance runners and randomly assigned then to one of two groups: The first group received 40 grams per day of the polyphenol soy protein complex or placebo (soy protein plus colorings) for 17 days. An intensive three-day running schedule occurred at day 14. Serum samples were taken at the start of the supplementation period, immediately after the third day of the running test, and again 14 days later.
Results showed that the serum samples from the polyphenol soy protein complex group did show any antibacterial properties at any time.
On the other hand, significant anti-viral activity was observed with only the polyphenol group displaying a delay in the replication of the virus.
“The mechanism by which [polyphenol soy protein complex] and other flavonoids provide protection from virus infections remains to be determined,” wrote Ahmed and her co-workers.
“[W]e found that pre-incubation of cells with serum from [polyphenol soy protein complex]-supplemented individuals for 4 h provided significant and sustained protection against killing by VSV, whereas the addition of serum at 0 h following viral infection did not result in sustained antiviral activity during the recovery period. This result suggests that [polyphenol soy protein complex] in serum must induce antiviral activity prior to virus infection of cells in order to target and inhibit the early steps of the virus replication cycle.
“Proposed mechanisms for this suppression include blockage of virus binding to the host cell plasma membrane, alteration of essential viral proteins and induction of cellular antiviral responses targeting specific steps in the viral replication cycle.”
Source: Phytotherapy Research
December 2014, Volume 28, Number 12, Pages 1829-1836 doi: 10.1002/ptr.5208
“The protective effects of a polyphenol-enriched protein powder on exercise-induced susceptibility to virus infection”
Authors: M. Ahmed, D.A. Henson, M.C. Sanderson, D.C. Nieman, N.D. Gillitt, M.A. Lila