Still skeptical about claims that certain supplements can combat colds? New evidence: Researchers analyzed 15 clinical trials involving a total of 1,360 participants of all age groups, comparing the effectiveness of zinc (in various forms and dosages) to a placebo for preventing or treating the common cold.

Results: People who took zinc for at least five consecutive days beginning within 24 hours of getting the sniffles experienced significantly less severe symptoms… and they were only about half as likely as placebo users to still have cold symptoms after seven days. Also: Participants who took zinc daily for at least five months reduced their chances of catching a cold by about one-third, compared with placebo users. Theory: Zinc is thought to work by inhibiting replication of the rhinovirus responsible for most colds. Reported side effects of zinc lozenges (but not syrup or tablets) included mild nausea and an unpleasant taste in the mouth.

More study is needed to confirm zinc’s benefits and determine the optimal dosage, researchers noted. In the meantime: You can talk to your doctor about taking zinc supplements when you have a cold… or starting now to prepare for the upcoming cold season. The safe upper limit for adults is set at 40 mg of zinc per day. Also discuss naturally zinc-rich foods, such as barley, buckwheat, bulgur and oat bran… black-eyed peas, chickpeas, kidney beans and lentils… crabs, oysters and poultry… and pine nuts.