Will vitamin C really boost my immune system if I up my intake this winter? -Robert R., Bloomington, MN
Yes and no. When used on a regular basis, vitamin C can shorten the duration of a cold by about 10%. Keep in mind, the average cold lasts five to seven days, so that 10% equates to merely shaving off a few hours. “The short answer is, it won’t make much difference to the average person,” says Joseph Raduazzo, M.D. “But it may help under extreme conditions.” That is, for “marathon runners, skiers, or soldiers on Arctic exercises.” We’re not sure what you’re into, Rob, but we’d recommend increasing your vitamin C intake regardless—even if you’re not heli-skiing behind enemy lines.