What the Science Says About Vitamin C and Colds

You Should Know: When you feel a scratchy throat or the first hint of sniffles, many of us head straight for the vitamin C supplements. It’s a widespread belief because the vitamin supports immune health. But research consistently shows that people who take these supplements are just as likely to catch a cold as those who don’t. 

Going Deeper: Some studies suggest supplementation may slightly shorten the duration of symptoms — by about 8% in adults — but the effect is modest, meaning a day at most. And taking it after symptoms start doesn’t appear to help much. There’s one group that may benefit more: Endurance athletes or people under extreme physical stress. Even then, it’s hard to separate the effects of vitamin C itself from the fact that supplement users tend to be more health-conscious overall.

Takeaway: Vitamin C supports general health, but it isn’t a reliable cold deterrent. In fact, some experts suggest focusing instead on vitamin D, which has stronger evidence behind its role in immune health.

Bottom Line: For most people, vitamin C supplements are safe when taken within recommended limits. But you’re likely getting enough already if you eat plenty of fruits and vegetables.