The Linus Pauling Institute says that vitamin C is safe even at high doses, such as 10 g per day. However, it recommends an upper limit of 2 g per day for adults, as higher doses have no apparent increased benefit. The institute has determined that the scant evidence for risks associated with vitamin C are miniscule in comparison to this nutrient's beneficial effects.
Role of Vitamin C
Vitamin C is an essential nutrient for maintaining normal health. Also known as L-ascorbic acid, vitamin C must be obtained from food since your body cannot make it. This vitamin is necessary for protein metabolism and the synthesis of neurotransmitters. It also is a powerful antioxidant that protects molecules from degradation. One of its most important functions is in the process of making collagen, which forms the connective tissues in ligaments, tendons and muscles.
Vitamin C Benefits
The Linus Pauling Institute says maintaining adequate levels of vitamin C are associated with a reduced risk of cardiovascular disease. This vitamin has also shown evidence of lowering the risk of stroke, cataracts and cancer. Vitamin C has had positive effects on cells in the immune system. The institute says such results lead to the widely held belief that vitamin C boosts immune function and protects against viral infection. However, conflicting reports do not support a direct association, and further controlled human studies are needed.
Possible Problems
A dietary insufficiency of vitamin C can cause the condition known as scurvy. Scurvy, which can be fatal, is caused by abnormally formed connective tissue. However, the dangers of too much vitamin C are not as well established. It was long thought that too much vitamin C produced kidney stones. This belief came about because kidney stones can be formed from by-products of vitamin C metabolism. The Linus Pauling Institute says the association between vitamin C and kidney stones is unfounded. Research suggests possible problems with doses of vitamin C exceeding 10 g per day, but no evidence exists in humans for toxicity at high doses.
Vitamin C Dosage
Even at high doses, vitamin C's benefits far outweigh its possible risks, and any evidence to the contrary is scant at best. Also, very high doses do not appear to be more beneficial than lower doses of vitamin C. The upper tolerable level established by the Linus Pauling Institute is 2 g per day for adults over 19 years old. However, the recommended dietary allowance, or RDA, for vitamin C in adults over age 19 is 90 mg for men and 75 mg for women. Both the upper tolerable level and RDA vary according to age in younger people.
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