Research: Vitamin C does little to prevent colds

But according to Tammy Roberts, a nutrition and health education specialist with the University of Missouri Extension, research offers little support that the extra vitamin C reduces symptoms – or the duration – of a cold, except in extreme situations.

“Several well-designed studies have been conducted to test whether taking vitamin C could reduce the risk for developing a cold or lessen the symptoms,” Roberts said in a news release. “The conclusion of the studies was that vitamin C did not reduce the risk for developing a cold.”

In some studies, cold symptoms were less severe in groups taking vitamin C, but not enough to recommend taking extra vitamin C to treat cold symptoms.

“Many people have thought that they needed to take mega doses of vitamin C to treat a cold. In the few instances where there was less severity of the cold with vitamin C supplements, 250 milligrams per day helped just as much as 1,000 milligrams or 4,000 milligrams,” Roberts added.

There have been some studies where vitamin C taken in doses of 200 milligrams per day did decrease the risk of developing a cold by as much as 50 percent.

“People who are living in extreme circumstances such as soldiers participating in sub-arctic exercises, marathon runners and skiers are the people who can benefit from vitamin C for cold prevention,” Roberts said.

The recommended dietary allowance for vitamin C is 90 milligrams a day for adult males and 75 milligrams per day for adult females. Vitamin C is found in abundance in citrus fruits but is also prevalent in other fruits and vegetables.

Vitamin C, also known as ascorbic acid, has several important functions in the body, including the production of collagen. Collagen is the connective tissue that helps hold muscles, bones and other tissues together. Vitamin C also helps to heal cuts and wounds, helps keep gums healthy, helps to prevent bruising and works as an antioxidant to prevent damage to body cells.