CORVALLIS - A variety of studies done by different researchers in recent years have shown the value of diets high in vitamin C, or the use of vitamin C supplements.
Many, but not all of the studies showing the value of vitamin C were by comparison to diets deficient in that essential nutrient, said Balz Frei, professor and director of the Linus Pauling Institute at Oregon State University. Most of them were related to the role of vitamin C as an antioxidant, but some of the findings may be linked to other metabolic roles it plays as well.
OSU scientists in a recent professional publication called for the increase of the official RDA for vitamin C to be raised from 60 milligrams per day to 120 milligrams.
Findings of the various studies included:
- Two studies found a significant reduction in the oxidative potential of LDL, or "bad" cholesterol in people taking vitamin C supplements.
- Two studies found an inverse correlation between vitamin C status and total serum cholesterol.
- Four studies showed an increase in blood vessel dilation when patients with cardiovascular disease took fairly high dosage supplements of vitamin C.
- One study found a 62 percent lower risk of cardiovascular disease in a population of elderly men and women consuming more than 388 milligrams a day of vitamin C, compared to those consuming less than 90 milligrams a day.
- Moderate supplements of vitamin C have been shown to greatly reduce chest pains from unstable angina pectoris.
- A dietary intake of vitamin C from both diet and supplements of about 300 milligrams a day was associated with a 21 percent risk reduction of all cancer in men.
- One study showed an intake of 300 milligrams or more of vitamin C a day was associated with a 70 percent reduced risk of cataract, which is the leading cause of blindness in the world - but with an intake level of 120 milligrams a day, the only intervention trial which was conducted showed nonsignificant reductions in cataract risk.
- Several studies have shown that the requirement for vitamin C is higher in smokers than in non-smokers; pregnant or lactating women; and the elderly.
- Two recent studies found that patients with Alzheimer disease have low plasma vitamin C concentrations despite an adequate diet, and that supplementation with vitamin C may lower the risk of Alzheimer disease.