CBC’s Marketplace is Wrong About Vitamin C

CBC’s Marketplace put a scathing article up on the CBC website today criticizing vitamin C. But it includes many unreferenced claims that are contrary to the scientific evidence, including the claim that vitamin C does not  help fight colds. . . .

The Marketplace article reports Dr. David Agus as saying that the belief that vitamin C fights colds “is a myth that the science doesn’t back up.”

Agus says, “If you have Vitamin C, a cold will last seven days. If you don’t have Vitamin C, your cold will last a week.”

Marketplace didn’t ask Agus to provide evidence for his claim in the article, and they didn’t give anyone the opportunity to provide evidence to the contrary: reporting that is one sided and irresponsible.

In fact, vitamin C does reduce the length of a cold. Double-blind research shows that, compared to a placebo, vitamin C reduces the length of a cold by a full 59% (that’s 2.87 days instead of seven in Dr. Agus’ example: a big difference when you’re feeling lousy). The study compared just 1g of vitamin C to a placebo every day for eight weeks. In the vitamin C group, there was a 45% reduction in the risk of getting a cold and a 59% reduction in duration if you did get one (Nutrients 2014;6:2572-83). That means that vitamin C both prevents and treats colds.

Other research has found even more impressive results: just 500mg a day of vitamin C makes you 70% less likely to catch a cold than if you were taking a placebo dose of 50mg (Eur J Clin Nutr 2005;60:9-17). A review of twenty-one studies that used 1-8g of vitamin C found that, in each of them, vitamin C reduced the length and severity of colds by 23% (Scand J Infect Dis 1994;26:1-6). Taking at least 2g a day works even better (Med Hypotheses 1999;52:171-8).