While the flu has gotten all the publicity, thanks to the unexpected shortage of this year's vaccine, influenza is just one of many diseases that pounce during the winter months. So even if you do get a flu shot this year, it will protect you against only a limited number of infections.

The good news: There are plenty of other ways to help reduce the risk of annoying and sometimes dangerous illnesses, and none of these measures involves waiting in long lines, winning a vaccine lottery or taking a quick trip to Canada.

The most widely promoted disease-fighter is that cornerstone of personal hygiene, regular hand-washing. Other simple steps include smart eating, moderate exercise and good sleep. Here's what experts -- and the latest science -- suggest:

Walk daily. Besides burning calories, walking helps strengthen the immune system by briefly increasing levels of white blood cells that serve as a key line of defense against infection. In fact, regular walking may protect you from common winter illnesses. Studies show that people who walk regularly have half the number of sick days for colds and upper respiratory infections as those who don't walk at all, according to David Nieman, professor of health and exercise science and director of the Human Performance Laboratory at Appalachian State University in Boone, N.C.

"No medicine, dietary supplement or other strategy has emerged to be as powerful as a 30- to 45-minute daily walk," said Nieman, co-author of a new study on walking and immunity slated for publication in the January issue of Medicine and Science in Sports and Exercise. Nieman and his colleagues report that half-hour walks produced favorable immune responses that last for a few hours. That's another reason to keep moving throughout the day rather than bunching up all your activity into a single session.

Have a handful of almonds or sunflower seeds. Both are rich in vitamin E, an antioxidant proven to counteract oxygen damage to biomolecules. New research hints that vitamin E may also help reduce the number and duration of common colds and other upper-respiratory infections. In a recent study of nursing home patients published in the Journal of the American Medical Association, Tufts University researchers reported that participants who received 200 international units of vitamin E daily had fewer upper-respiratory infections than those who received a placebo.

"But don't rely on dietary supplements," Nieman said. "Eat a well-balanced diet." Good food sources of vitamin E include avocados, safflower oil, pine nuts, tomato paste, canola oil, peanut butter and wheat germ. Most are calorie-rich, so monitor amounts carefully.

Practice tai chi. In a study at the Neuropsychiatric Institute of the University of California, Los Angeles (UCLA), healthy people age 60 and older practiced this ancient martial art three times a week for 15 weeks. Researchers found that this boosted the participants' levels of the white blood cells (T cells) that seek and destroy varicella zoster, the virus that causes shingles and chickenpox.

While only immunity against shingles was measured in this study, "there's no reason to believe that tai chi will just be specific" for that condition, said Michael Irwin, professor of psychiatry and biobehavioral science at UCLA and the lead author of the study, published in the journal Psychosomatic Medicine. Also, he said, yoga, Pilates and other activities may have similar effects, but they have yet to be studied.

Eat enough calories. When intake dips too low, the immune system doesn't function at optimal levels. What's too low a calorie count? Nieman and his colleagues have found T cell function is suppressed in women who eat less than 1,300 calories per day. No similar studies have been done in males, but Nieman estimated 1,500 calories or above would be a safe level for men.

Get enough zzz's. Sleep deprivation is widespread. Yet missing even a few hours of sleep "produces quite striking declines in natural killer cell activity," Irwin said. These cells destroy others that are infected with viruses and bacteria. Also depressed by lack of sleep: production of chemical messengers that turn on the immune system. "Good sleep is required for activation of the immune system to occur," Irwin said.

Eat some yogurt -- or other foods that contain live cultures of lactobacillus and other "friendly" bacteria. A number of studies suggest that these bacteria help boost the immune system in children and adults. They appear to protect against diarrheal illnesses and upper-respiratory infections, and may even help thwart the bacteria linked to stomach ulcers.


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