To guard against a winter rise in respiratory infections, some people “boost” their immune system with supplements and nutrient-rich foods. For a subset, that is in addition to social distancing, masking, and flu and COVID-19 vaccinations, which reduce the risk of getting an infection or developing severe symptoms; for others it’s their sole defense.
They’re hoping to use minerals like zinc and vitamins including C and D to amp up the immune response in case an infection strikes. Although such efforts are unlikely to prevent an infection, they could support a person’s immune system. But for an average person who eats well, exercises, and gets enough sleep, supplements may not do a whole lot, says immunologist Scott Read at Australia’s Western Sydney University, unless they’re deficient.
If someone wants to consume extra vitamins or minerals to strengthen their defenses, “there’s nothing harmful about that,” says Carol Haggans, a dietitian and consultant at the National Institutes of Health’s Office of Dietary Supplements, as long as the amounts don’t exceed daily limits set by the Food and Nutrition Board of the National Academies of Sciences, Engineering and Medicine. “High intakes can be toxic,” she warns. It’s also worth noting that supplements can interfere or interact with some medications, so it is best to check with your physician before taking them.