Oxidative damage to DNA, proteins and lipids appears to be a major contributing factor in aging and the degenerative processes that accompany it, including cancer, heart disease, cataracts, and cognitive dysfunction. Numerous epidemiologic studies have found that persons with lower intake of antioxidant nutrients or the fruits and vegetables that provide them have a higher risk of almost every type of cancer. In many studies, those with low intake had twice the risk of those with high intake. A large-scale follow-up study found that persons with a low vitamin C intake had a statistically significantly higher risk of heart disease mortality and total mortality over the subsequent 10 years. In addition, several studies have found that persons with low intake of antioxidant nutrients such as vitamin C and carotene had significantly increased risk of developing age-related eye diseases such as cataracts. Although many older people consume more antioxidants than younger people, very substantial proportions of older persons have very low intakes and blood levels. Among white men 65–74 in the U.S., 15% have blood ascorbate levels below 0.4 mg/dl, the lower boundary of “normal.” Among black men of that age, 25% have levels below 0.4 mg/dl.
Persons with high intakes of dietary vitamin C or citrus fruit have repeatedly been found to have a lower risk of developing cancer. In addition, recent research indicates an important role in heart disease and other disabilities of aging. This paper will summarize the epidemiologic literature briefly, and provide data on intake of this vitamin in the United States.
Vitamin C has numerous biologic functions, including collagen, hormone and neurotransmitter synthesis. Its role as an antioxidant and free radical scavenger may be of primary importance in many of its roles in disease prevention. Oxidative and free radical damage to DNA and cell membranes is an important factor in cancer initiation, and it is clear that ascorbic acid can help prevent such damage.
KeywordsCataract Free Radical Scavenger Carotene Citrus Fruit Dietary Vitamin
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