If your mom was one to push the orange juice when you were sniffling and sneezing, she may have had good reason.

A review of more than 30 studies shows that taking one 1,000-mg vitamin C supplement per day may help shorten the duration and severity of cold symptoms, especially when you're under stress. You don't need to take a supplement 365 days a year, though, because vitamin C doesn't prevent colds from coming on. It just might help once that cold arrives, though.

There's a lot of speculation about the merits of vitamin C. Some believe in it; some think it's pretty useless. Whatever your view, the current recommended dose of this vitamin is 60 mg daily. One eight-ounce glass of orange juice contains 97 mg.