We know that hard training just before a pre-race taper can improve your race performance. However we also know that the same hard training can lead to illness, especially in the form of upper respiratory tract infection. So the key question becomes: How do you get the benefit without the risk?
A new study from running-and-immunity expert David Nieman, Ph.D., points to a helpful approach. And in doing so, the same study may have uncovered a novel explanation for the health benefits of regular exercise.
Nieman and colleagues asked an experienced group of runners to jump from their normal average of 7.2 kilometres a day to 24 kilometres/day on three successive days. Some of the runners received a pill containing blueberries and green tea extract, while the others got a placebo.
“[Our] results indicate that polyphenol complexes containing blueberry and green tea have the potential to protect athletes from virus infections following rigorous exercise,” the researchers concluded. Back in the 1980s, Nieman was the first to show that marathoners often come down with a cold after their race, due to a short period of reduced immunity.
Of course, you can’t simply expose a group of tired distance runners to viruses; ethics committees don’t allow possibly harmful experiments. So Nieman devised a different approach. He took blood samples from their runners, and then exposed the blood samples to viruses and fast-growing cancer cells.
“The runners on the blueberry plus [green tea extract] product, versus the placebo runners, had higher levels of gut-derived polyphenols in their blood,” Nieman told Runner’s World Newswire by email. “We believe that these exerted the anti-viral influences.”
The polyphenol pill used in the study included the equivalent of 3 cups of blueberries and 1.5 cups of green tea extract per day. Nieman and his fellow researchers created the pill from available materials; no equivalent of the pill is currently available commercially.
Nieman used the rapidly developing field of metabolomics to identify the extract’s apparent power. Metabolomics allows investigators to simultaneously analyze the effects of hundreds of metabolites (such as foods, vitamins, proteins, and hormones) in the body, where formerly they could look at only one or two. “The use of metabolomics has opened the door to new discoveries and improved interpretation of nutritional interventions,” noted Nieman.
In a new and unexpected finding, Nieman discovered that the body’s enhanced blueberry and green tea extract absorption occurred in the colon rather than the intestines. Many polyphenols are not well absorbed by the body, but it has been believed that most absorption occurs in the intestines.
Runners get extra absorption in the colon, because exercise causes a “leaky” colon. This doesn’t sound good, but it might prove beneficial for enhanced nutrient uptake. “A leaky gut helps the body return more plant phenolics back into the system where positive effects take place,” said Nieman.
In effect, regular exercisers get more bang for their buck when it comes to fruit and vegetable metabolites.
”Our research supports the practice of consuming five to nine fruits and vegetables per day,” said Nieman. “The combination of running and high fruit/vegetable intake promotes fitness and health. Part of this happens through exercise’s influence on the gut.”
