A study was recently published in the Cochrane Database of Systematic Reviews. 1 Here's why it matters.
The common cold is common. There are over 200 different viruses that can cause them. It's a major cause of missing both work and school and the leading cause of acute morbidity and doctor visits in high-income countries. And because colds are caused by viruses, antibiotics don't help, but that does not stop the quest for a cure. Using vitamin C became particularly popular in the 1970s, when Nobel Laureate Linus Pauling gave vitamin C for colds his seal of approval, on the basis of early placebo-controlled trials. 3
That was then. Now, in this new review, 72 studies were analyzed. Only those using supplement doses of 200 mg or higher were included. The conclusion:
1 - First, for preventing colds – 20 trials with more than 11,000 patients showed that for most people, vitamin C didn't help much. It reduced colds, but only by 3%. For those under high physical stress – marathon runners, skiers, and soldiers doing sub-Arctic exercise – the results were dramatically different. The extra vitamin C in these patients cut colds in half.
2 - Next, duration of symptoms – nearly 10,000 colds and 31 studies. The conclusions: for adults, an 8% reduction in duration of cold symptoms and nearly twice that for kids, a 14% reduction.
3 - Finally, for severity of cold symptoms – in kids, doses of 1-2 g daily seemed to help.
The bottom line: More randomized controlled trials are needed. But on the basis of the data so far, vitamin C doesn't do much to keep you from getting a cold unless you're seriously stressed.
On the other hand, it's cheap and relatively safe, although a recent study says it may increase risk for kidney stones. 2 And it does seem to help a little with how long your cold lasts and how bad it is.
Dr. Sandra Fryhofer.
Medscape Internal Medicine © 2014 WebMD, LLC
Cite this article: Vitamin C and Colds: The Bottom Line Medscape. Mar 20, 2014.
Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013;1:CD000980. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD000980.pub4/abstract Accessed March 11, 2014. ↩
Thomas LD, Elinder CG, Tiselius HG, Wolk A, Akesson A. Ascorbic acid supplements and kidney stone incidence among men: a prospective study. JAMA Intern Med. 2013;173:386-388. ↩
Pauling L. Vitamin C and the Common Cold. New York: WH Freeman & Co; 1971. ↩