San Francisco Chronicle, October 2, 2012
Myth: Vitamin C prevents the common cold.
Fact: After decades and dozens of studies, it appears the idea that vitamin C prevents colds is just an old wives’ tale. But there is some evidence that high doses of the vitamin, which is found in citrus fruit and other produce, may slightly shorten the length of a cold.
The conclusions come from a 2004 study by researchers at Australia’s National Centre for Epidemiology and Population Health who reviewed more than 30 published trials investigating vitamin C’s ability to prevent and treat the cold.
Combined, the studies involved more than 10,000 participants. The reviewers determined that people taking vitamin C daily, in doses as high as 1 gram, caught roughly the same number of colds as people who were not taking extra vitamin C.
The combined trials also found that cold symptoms did not last quite as long in people who took extra vitamin C daily through several winter months. On average, colds for these people were about half a day shorter than for people who did not take vitamin C.