Vitamin C (ascorbic acid) is the most commonly used supplement of all the recommended daily vitamins, and it’s no wonder. In the 1970s Nobel Prize-winning chemist Linus Pauling promoted the idea that mega-doses of vitamin C could be used for a number of health benefits, including prevention of the common cold. This possibility naturally had very wide appeal, since a great many people suffer through a cold on a semi-regular basis. We’re particularly vulnerable during the winter months, when we’re stuck indoors with other people who have been infected with the cold virus.
Pauling also promoted the idea that high doses of vitamin C could be effective in treating heart disease and in reducing the risk of infection and cancer. However, since Pauling’s death in 1994 there has been some controversy as to whether high doses of vitamin C really have a positive effect on the immune system.
Scientists do agree that the regular intake of moderate doses of vitamin C (equal to about 200 mg per day) can lessen the severity and shorten the duration of the common cold. However, they also agree that vitamin C does not generally lower the likelihood of being infected by the cold virus. There is a notable exception for one part of the population, though. It has been shown that vitamin C does cut the incidence of colds in half for people involved in intensive physical activities, such as professional skiers and marathon runners.
What about the idea of mega-doses? A study conducted by the National Institutes of Health (NIH) concluded that any vitamin C taken in excess of saturation (that is, beyond the point where the body can absorb and make use of it) is essentially useless and ends up being excreted in the urine. However, it’s also worth mentioning that all mainstream research on vitamin C had been undertaken using small to moderate doses.
Drs. Steve Hickey and Hilary Roberts decided to investigate the issue further and examined the NIH study in detail as well as clinical reports and independent scientific reports covering a 50-year period. In their analysis, they found evidence for the usefulness of vitamin C in boosting the immune system and in treating cancer and heart disease. They also questioned the validity of the NIH findings, noting that the NIH measured levels of vitamin C only in the blood and in white blood cells, which are the cells that are first in line to absorb vitamin C in the body. Hickey and Roberts suggest that the NIH did not take into account how the other cells in the body utilize vitamin C, especially given the large amount of clinical evidence as to its effectiveness.
Since vitamin C is found abundantly in a wide range of fruits and vegetables and is inexpensive to manufacture, the pharmaceutical companies do not have great interest in paying for large-scale studies on the effect of large doses of vitamin C. Vitamin C has been demonstrated to increase the production of antibodies and white blood cells and to increase levels of interferon, a substance that helps protect cells from invasion from viruses. Its antioxidant activity aids in keeping cells healthy so they are better able to guard against disease.
If you are interested in exploring the benefits of vitamin C, it can be found in greatest amounts in citrus fruit, bell peppers (particularly the red peppers), strawberries, broccoli and green leafy vegetables. Supplements are also widely available, and many nutritionists suggest that it’s best to take 250-500 mg of these twice a day with meals rather than taking your daily dose all at once.