Your immune system is complicated; keeping it healthy isn’t
By Wendy Haaf
To judge by some headlines—“9 Power Foods That Boost Immunity!”—you’d think half of us are walking around with a sluggish infection-fighting system that could be bolstered by consuming a specific food or supplement. You probably already suspect that’s not quite true.
There are, however, things that can affect the functioning of the immune system, which is an incredibly complex defensive force.
- Aging. Due to changes that occur over time (such as a diminished capacity for certain immune cells to renew themselves), “our immune systems become a little less efficient in later life,” notes Marc Ouellette, scientific director of the Institute of Infection and Immunity at the Canadian Institutes of Health Research and a professor of medicine in the Department of Microbiology, Infectious Disease, and Immunology at Laval University in Quebec.
- Toxins. Exposure to substances such as mercury, arsenic, and pesticides can disrupt the normal functioning of immune cells, Ouellette says.
- Smoking. This habit suppresses infection-fighting ability in a number of ways, one of which is by suppressing the activity of certain immune cells.
- Nutritional status. “Malnutrition will reduce the efficacy of your immune system,” Ouellette says. However, unless you have a deficiency of a particular nutrient (such as vitamin D), there’s no solid scientific evidence that taking vitamin supplements will reduce your susceptibility to infection. Evidence is similarly lacking for herbal preparations and so-called super-foods.
- Health conditions. A number of common chronic health problems, including diabetes and obesity, increase vulnerability to infection.
- Exercise. Epidemiological evidence suggests that regular moderate exercise—such as walking at a brisk clip for 30 to 60 minutes a day—protects against upper respiratory tract infections. There’s an exercise sweet spot, though: extremely intense or prolonged workouts (sessions lasting 90 minutes or more) appear to have the opposite effect.
- Sleep. Studies suggest that people who get poor-quality or insufficient sleep (fewer than seven hours a night) are more likely to get sick after being exposed to cold viruses.
- Vaccinations. Vaccines stimulate the immune system to produce cells capable of recognizing and neutralizing specific strains of viruses or bacteria before they can cause infection.
- Probiotics. Can consuming beneficial bacteria improve your immune function? “Research is ongoing to see whether this is indeed the case,” Ouellette says. To date, certain probiotic strains have been shown to reduce the risk of developing antibiotic-associated diarrhea and (in hospitalized patients) diarrhea caused by C. difficile infection.
So what’s the best way to keep your immune system in good working order?
“Healthy living: eat well, exercise, and get enough sleep,” Ouellette advises. “There’s no magic here.”