Eating to Arm the Immune System

There’s more to keeping well than washing your hands frequently, getting vaccines on schedule and eating five fruit and vegetable servings a day (though that can certainly help!). Scientists in the fledgling field of nutritional immunology are zeroing in on the specific nutrients and other dietary components that keep the immune system strong.

The goal: “To help establish the guidelines for food intake and supplement use for reducing the risk of diseases in which disordered immune function plays a role,” says Dayong Wu, M.D., Ph.D., a scientist at the USDA Human Nutrition Research Center on Aging at Tufts University in Boston.

That’s particularly important as people age. Older people tend to have lower defenses against potentially harmful viruses and bacteria, increasing their risks for infectious diseases, Wu says. Plus many experience the kind of low level, chronic inflammation in the body’s cells and tissues that contributes to cardiovascular woes, diabetes and Alzheimer’s disease.

Often a deficiency of a critical vitamin is the culprit behind lackluster immunity. “Vitamins like A and D function in ways that directly turn genes on or off,” says Adrian Gombart, Ph.D., principal investigator at the Linus Pauling Institute at Oregon State University. “The lack of these nutrients can lead to changes in gene expression that can impair immune cell function.” Here are some initial findings that he and other scientists have identified about specific nutrients and the body’s disease-defense mechanisms:

Zinc: Research shows a deficiency of this mineral, which is common in older people, triggers a tsunami of molecular changes that ultimately decreases natural killer cells, the immune system’s first line of defense again viruses, bacteria and cancer cells.

Vitamin E: Dietary Vitamin E supplementation can help “reduce the risk of acquiring upper respiratory infections in nursing home residents,” Wu says.

Vitamin D: “There is some evidence that vitamin D supplementation may reduce the incidence of flu, though such studies are relatively small,” Gombart says. “Because vitamin D is important for proper immune function, it is important to make sure that individuals have sufficient levels so that if an infection occurs, then it is countered with an optimal immune response.”  Like most of the emerging science of nutritional immunology, more research is needed before firm recommendations can be made.

CONNECT THE DOTS

For more information about the effects of nutrition on immunity and other health indicators, check out the Micronutrient Information Center at the Linus Pauling Institute at Oregon State University. Also see Tuft University’s Modified MyPyramid for Older Adults, which is designed for the dietary needs of people over 70.