Millions of Americans, through habits acquired from popular magazines, take vitamin C pills at the first signs of the common cold.
However, recent research by a Penn professor has shown that vitamin C alone might have a deleterious effect on the human body by forming molecules that can damage DNA.
Vitamin C, a part of the antioxidant family, helps to destroy certain harmful chemicals called free radicals.
But in test tube studies, Pharmacology professor Ian Blair and his colleagues discovered that lipid hydroperoxide, a compound produced in the body by fat in the diet, can be converted to DNA-damaging chemicals called genotoxins by vitamin C alone.
The vitamin has also been celebrated as a way to prevent cancer, but Blair said that "no one has shown, in any study, that vitamin C is an anti-cancer agent."
Blair, who has been working in this field for over 10 years, decided to test vitamin C after similar chemical ions produced negative effects on lipid hydroperoxide as well by forming reduction reactions.
Because test-tube conditions might not necessarily reflect conditions in the human body, Blair will eventually expand his study to mice and human models.
While vitamin C has a beneficial effect as part of a balanced diet, Blair's findings call into question the effectiveness of vitamin C alone.
"Vitamin C does some good things in a good diet by having an additive effect," Blair said. "There is no evidence that vitamin C is a supplement for a good diet."
"The study must have made me some good friends in the supplement industry," Blair joked.
Blair admitted that there is a possibility that other antioxidents alone could work in the same damaging way as vitamin C, boosting his claim that "there's nothing better than a balanced diet."
In addition to possible negative effects of vitamin C alone, Blair also warned against supplements because the supplement industry is largely unregulated.
Despite the lack of regulation, Blair was "astonished at how large the market is."
According to a market research study by the Hartman Group, Americans spent over $700 million on vitamin C pills in 1999.
"I would say that right now, you're better off buying an orange than buying a vitamin C pill," Blair said, adding that oranges had other nutrients in addition to vitamin C.
The notion that vitamin C helps fight colds comes from the sixteenth century, when scientists discovered that citrus fruits -- a major source of vitamin C -- could prevent the occurrence of scurvy. As a result, sailors began taking citrus fruits on their journeys.
The study was published in the June 15 issue of the journal Science.
