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Too many antioxidants could be bad for muscle function

Kathleen Blanchard's picture

Antioxidants are everywhere – the word can be found on the grocery shelves in abundance on a wide array of packages, juices, teas, and cereals. But scientists caution that antioxidants could just be bad for us by causing muscles to function poorly.

The findings come from researchers at Kansas State University’s Cardiorespiratory Exercise Laboratory who have been studying the effects of antioxidants in food to find ways to keep muscles working well during physical activity. The scientists found that sometimes antioxidants actually impair muscle activity.

Antioxidants are substances that have been studied for their role in disease prevention. Free radicals from pollution, tobacco, and environmental toxins can damage cell. Antioxidants repair cells, and have been studied for their role in disease prevention and prolonging life. Other studies show that oxidative stress leads to a longer life.

"Antioxidant is one of those buzz words right now," said Steven Copp, a doctoral student in anatomy and physiology from Manhattan and a researcher. "Walking around grocery stores you see things advertised that are loaded with antioxidants. I think what a lot of people don't realize is that the antioxidant and pro-oxidant balance is really delicate. One of the things we've seen in our research is that you can't just give a larger dose of antioxidants and presume that there will be some sort of beneficial effect. In fact, you can actually make a problem worse."

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A group of scientists at Kansas State study animals in the Cardiorespiratory Exercise Laboratory, located in the College of Veterinary Medicine. The group has studied the effects of different doses and types of antioxidants on muscle control and blood flow, especially as it relates to chronic diseases such as heart failure as well as with aging.

"If you have a person trying to recover from a heart attack and you put them in cardiac rehab, when they walk on a treadmill they might say it's difficult," says Professor David C. Poole from the departments of kinesiology and anatomy and physiology. "Their muscles get sore and stiff. We try to understand why the blood cells aren't flowing properly and why they can't get oxygen to the muscles, as happens in healthy individuals."

The studies performed by the researchers show that some antioxidants are helpful for reducing the effects of poor oxygenation on the muscles, but in some cases they can rob the body of oxidants like hydrogen peroxide, making muscles function less efficiently. Hydrogen peroxide makes blood vessels dilate to improve oxygen delivery. Antioxidants can take away natural vasodilators leading to poor muscle function.

"It's really a cautionary note that before we start recommending people get more antioxidants, we need to understand more about how they function in physiological systems and circumstances like exercise," Poole said.

The findings show that we may not need to pluck too many antioxidants off the grocery shelves because they aren’t always good for you. The researchers hope to eventually make specific recommendations that can help chronic diseases and aging without causing harm from too many antioxidants, found in the studies to potentially lead to poor muscle function.

Kansas State University