Food alone can’t protect against the common cold or influenza, and the science isn’t yet clear on which or how much of some nutrients may help bolster immunity to reduce your risk of getting sick. But experts agree that a diet rich in a variety of produce, whole grains, lean proteins, and low-fat dairy products — along with adequate sleep, moderate exercise, and minimal stress — contributes to a well-functioning immune system and may promote a faster recovery if you do come down with a cold or flu. CookingLight.com: Choose healthful treats this holiday season
Water is the largest single constituent of the human body — contributing to at least half your body weight — but it’s “also a forgotten nutrient,” says Jennifer K. Nelson, M.S., R.D., director of clinical dietetics at the Mayo Clinic in Rochester, Minnesota. This essential nutrient (meaning it’s one the body can’t produce on its own) promotes healthy muscle, bone, and blood.
Adequate hydration is even more important once you’re sick because fluids lost through sneezing, watery eyes, and a runny nose need replacing. “When you have a mild fever, your body becomes more dehydrated as a result. So drinking plenty of fluids is probably the first line of defense,” Nelson says.
While it’s known that certain nutrients like vitamins C, E, and A, as well as the mineral zinc, are associated with immune functions, it’s hard to attribute specific immunity-boosting benefits to any one nutrient because of inconclusive research. “Many studies have been done in nutrition and immune function, involving numerous nutrients — and [they] come out with different, often contradicting results,” says Dayong Wu, Ph.D., a scientist in the Nutritional Immunology Laboratory, the USDA Human Nutrition Research Center on Aging, and assistant professor at the Friedman School of Nutrition and Science Policy at Tufts University.
Because a nutritional intervention may have different effects on people of different ages or nutrition status as noted in scientific studies, Wu says, it’s difficult to make broad recommendations based on study findings. “In general, it’s easier to see positive, immune-strengthening results by supplementing someone with a vitamin or mineral that he is deficient in,” he says. The same benefits may not confer to “people with adequate intake.”