4 Things to Fine-Tune Your Immune System

What multiplies as fast as a flu virus? Claims about immune boosters, most of which just boost a few bucks from your wallet. Here are the ones worth trying out.

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Go Nuts for Vitamin E

Immune cells can't function without proper nutrition, says Simin Meydani, PhD, director of the USDA Human Nutrition Research Center  at Tufts University. 

"In an outbreak, a deficiency of nutrients can be as dangerous as not washing your hands," she says. But many people don't get enough vitamin E, a proven immune enhancer, says Patricia Sheridan, PhD, at the University of North Carolina at Chapel Hill. 

You need at least 15 mg of vitamin E daily, she says, which you can get in a generous handful of almonds (7 mg of vitamin E per ounce). The elderly and people with weakened immune systems may need a supplement of 200 mg of vitamin E, Meydani believes.

In her study of nursing home residents, supplementing with that amount cut the risk of colds and flu by about 20 percent. Don't take more, though: One highly publicized study suggested that high doses (400 mg per day or more) could increase the risk of death.

 

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Don't Stint on Selenium

This trace mineral helps build immune system enzymes. Most people in North America aren't deficient but could use a little extra to sharpen their immune systems, Sheridan says. She recommends about 55 micrograms, which you can get in a tuna sandwich.

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Pop the Sunshine Vitamin

Vitamin D is needed to produce certain germ-killing proteins (a recent study suggests that low levels raise the risk of respiratory infection by more than 35 percent). Many people fall short, says Michael Holick, MD, professor of medicine at Boston University. You can't get much vitamin D from food, so Holick recommends that adults supplement with 1,000 IU a day.

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Work out in Moderation

Even a little exercise can wake up the immune system, says Thomas Lowder, PhD, at the University of Houston. (Exercise that wrecks you for days can actually make you more vulnerable, though.) In a 2006 study, women either exercised moderately five times a week or stretched once a week. By study's end, the exercisers were only one third as likely as the stretchers to be sniffling and sneezing.