Phytother Res. 2014 Dec;28(12):1829-36.

The Protective Effects of a Polyphenol-Enriched Protein Powder on Exercise-Induced Susceptibility to Virus infection

 

Maryam Ahmed1,* Dru Henson1, Matthew Sanderson1, David Nieman2, Nicholas D. Gillitt3, and Mary Ann Lila4.

1Department of Biology, Appalachian State University, Boone, NC 28608

2Human Performance Laboratory, Appalachian State University, North Carolina Research Campus, Kannapolis, NC 28081

3Dole Nutrition Research Laboratory, North Carolina Research Campus, Kannapolis, NC, 28081

4Plants for Human Health Institute, North Carolina State University, North Carolina Research Campus, Kannapolis, NC 28081

 

ABSTRACT:

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.

KEYWORDS: blueberry extract; green tea; polyphenols; virus infection

PMID: 25088029

 

Supplement:

While regular physical activity may be beneficial to health by promoting an anti-inflammatory environment in the body and reducing the risk of developing chronic diseases, strenuous exercise impacts a number of immune parameters to trigger inflammation and cause tissue injury (1). Studies have shown that prolonged, intense exercise induces structural damage to muscle cells, oxidative stress and immune dysfunction (2, 3). Furthermore, transient immunosuppression induced by extreme physical activity during periods of intensive training and competition is also associated with the risk of acquiring respiratory tract infections in humans.

 

The goal of our study was to measure the antiviral and antibacterial properties in the serum of long-distance runners following a 3-day period of intensified running. In addition, we were interesting in evaluating whether the serum of subjects supplemented with a blueberry and green tea-polyphenol-rich soy protein-based complex (PSPC) was more resistant to challenge with viral or bacterial pathogens. For this study, we supplemented experienced runners over a 17-day period with PSPC or Placebo. This included a 14-day pre-exercise period followed by a 3-day intensified running period (Figure 1). Blood was collected prior to supplementation, pre-exercise, following the 3-day exercise bout and 14-h post-exercise the following morning. Serum was separated and used in our in vitro assays to evaluate the antiviral and antibacterial activity in the serum of subjects. We hypothesized that ingestion of PSPC would protect athletes from infections following exercise due to the anti-microbial effects of polyphenols found in green tea and blueberries.

Figure 1

Figure 1: Exercise Sessions. Subjects in both the PSPC and Placebo groups trained normally during the 2-week supplementation period and then participated in a 3-day exercise session at the Human Performance Laboratory. Subjects ran on treadmills for 2.5-h at approximately 70% VO2max. Heart rate, rating of perceived exertion (RPE), and distance run were recorded every 30 minutes during the bout, with oxygen consumption and ventilation measured after one hour of exercise (Cosmed FitMate metabolic system, Rome, Italy). PSPC or Placebo supplementation was provided during the 3-day intensified exercise session.

 

It is widely accepted that polyphenols exert beneficial effects on human health, including antioxidant, anti-inflammatory and anti-microbial properties (4). The anti-viral effects of EGCG, a catechin found in green tea, is attributed to its ability to interfere with virus penetration into cells due to damage of the virus particle (5). Furthermore, tea catechins also bind to bacterial lipid bilayers and cause damage to the membrane (6). Anthocyanins and other flavonoids from blueberries also exhibit anti-microbial activity. For example, they have been shown to inhibit the infectivity of influenza virus and prevent the growth of several bacterial pathogens (7, 8). These studies are promising, but they do not address the anti-microbial effects of polyphenolic derivatives in humans. Therefore, our study is the first to address whether compounds found in the serum of athletes have the capacity to protect them from infections following rigorous exercise.

 

To test our hypothesis, we asked whether serum from PSPC-supplemented athletes would protect cells in culture from killing by vesicular stomatitis virus (VSV). VSV is a prototype negative strand RNA virus in the same family as influenza and rabies virus. It is an excellent model system due to the ability of this virus to target multiple tissue types, including neuronal and respiratory cells. We found that serum from subjects who ingested PSPC protected cells from the exercise-induced susceptibility to killing by VSV. In fact, this resistance to virus-induced killing was maintained during the 14-h recovery period. Further studies indicated that PSPC serum contained factors that interfered with the ability of the virus to effectively infect and replicate within cells. These data are encouraging and suggest that PSPC could potentially be used as a supplement for athletes to boost their resistance to virus infections following intense training regimens.

 

How about bacterial infections? To assess whether serum from supplemented athletes would protect them from bacterial infections, we measured the growth of both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) exposed to serum from Placebo versus PSPC supplemented runners. Interestingly, we observed an exercise-induced increase in growth of E.coli and S. aureus in both groups. Furthermore, in contrast to our expectations, PSPC-supplementation failed to ameliorate this increased susceptibility to bacterial infections.

 

Figure 2. model

Figure 2: Model for antiviral activity of PSPC. (1) Factors in the serum, such as EGCG, may interfere with viral attachment to host cells by damaging the virus particle, possibly by exerting physical damage to the viral membrane or altering the structure of viral glycoproteins. (2) Penetration of virus into host cells may be hindered by inhibiting the fusion of the virus envelope with the host plasma membrane. Alternatively, PSPC supplementation may affect the early steps of virus replication by providing factors to inactivate viral RNA polymerase and viral replication enzymes, or by binding to viral nucleic acid and capsid proteins. (3) PSCP may enhance the cellular antiviral response (type I interferon response) to inhibit virus replication or (4) stimulate immune cells to kill virus-infected cells and prevent virus spread.

 

Overall, we concluded that compounds in the serum of PSPC-supplemented athletes exert anti-viral activity and have the potential to increase resistance to viral infections following prolonged and intense exercise. What is the mechanism by which these compounds provide protection against virus infections? Figure 2 describes several possible mechanisms of action. First of all, it is possible that compounds in the serum damage the viral envelope and prevent binding of the virus to host cell receptors. Studies have shown that EGCG from green tea damages the physical properties of the viral envelope and partially inhibits neuraminidase (NS) activity (5). Secondly, it is possible that the virus is able to attach to host cells, but compounds in PSPC supplemented individuals interfere with virus penetration, perhaps by inhibiting the fusion of viral envelopes with host plasma membrane components. Another possibility is that pre-incubation with serum components induces an antiviral state in infected cells that render them more resistant to infection with VSV. This is an attractive hypothesis given the fact that we did not observe an antiviral effect when cells were treated with serum and infected with VSV at the same time. Lastly, polyphenolic compounds in the serum may be stimulating immune components to facilitate an antiviral state. Although we did not directly test this in our study, it would be interesting to directly measure changes in cytokines and immune cells involved in antiviral activity. Future studies seek to determine the mechanisms by which PSPC exerts an antiviral state.

 

Importance of this study: Our study has two main conclusions: First, it demonstrates that the serum of athletes subjected to intense and prolonged exercise contains physiological factors leading to increased susceptibility to both bacterial and viral infections, supporting data from other studies indicating elevated risk of acute respiratory illnesses. Secondly, the study shows that PSPC supplementation may increase the resistance of athletes to viral infections. These findings may lead to the development of PSPC supplementation as a means to boost anti-viral defenses during sessions of intense training and competition.

 

References:

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