Intriguing New Research Results on Vitamin C

Three recent studies investigated the relationship between vitamin C and lead levels in blood. One study by Dr. Y. Cheng and colleagues at Harvard, published in the American Journal of Epidemiology in 1998, found that older men who had the highest intake of vitamin C (more than 339 mg/day) had a lower level of lead in their blood than did men whose intake of vitamin C was less than 109 mg/day. Another study, published in the Journal of the American Medical Association in June by Drs. J. Simon and E. Hudes of the University of California, San Francisco, found that adults with the highest levels of vitamin C in serum had much lower levels of lead in their blood. The third study, reported in The Journal of the American College of Nutrition in 1999 by Dr. E. Dawson and colleagues at the University of Texas Medical Branch, Galveston, determined that supplementation with 1,000 mg/day of vitamin C in adult male smokers reduced blood lead levels by 81% after only one week, but that a dose of 200 mg/day of vitamin C had little effect. While the first two studies were observational—suggestive of a beneficial role of vitamin C in lowering blood lead levels—the third study was remarkable because it showed that large dose supplementation with vitamin C can dramatically lower lead levels.

At a recent meeting of the American Chemical Society in New Orleans, Dr. P. Samuel Campbell and colleagues of the University of Alabama presented results of an experiment of vitamin C and stress in rats. One group of rats was given 200 mg/day of vitamin C, and the control group did not get any extra vitamin C. After the rats were exposed to a stressful situation, those that received vitamin C had more IgG, an important class of antibodies, and less corticosterone, an adrenal hormone related to cortisol, which, in humans, has been associated with heart disease when chronically overproduced. Since rats synthesize vitamin C, it is difficult to extrapolate these results to humans, but Dr. Campbell estimated that the amount of supplemental vitamin C that produced these beneficial effects in rats corresponds to an intake of several grams in humans. These results offer more support to the concept that the need for vitamin C increases during stress.

A number of recent studies have demonstrated that vitamin C ameliorates oxidant stress induced by drinking alcoholic beverages. Using guinea pigs, Dr. M. Suresh and colleagues of the University of Kerala in India showed that alcohol reduced the vitamin C content in tissues, but that this effect was reversed by the co-administration of vitamin C. They also found that alcohol-induced hyperlipidemia and the amount of lipid peroxidation products were reduced by large amounts of vitamin C, which also had a favorable effect on the levels of antioxidant enzymes and vitamin E. Protective effects of vitamin C were also found in another guinea pig study. Dr. E. Ginter and colleagues at the Institute of Preventive and Clinical Medicine in the Slovak Republic gave large amounts of vitamin C to guinea pigs injected with alcohol and reported that vitamin C accelerated the metabolism of alcohol. In September, Dr. E. Meagher and colleagues of the University of Pennsylvania and the Florida Institute of Technology reported that daily doses of 2,500 mg of vitamin C reduced, by about 50%, the amount of urinary isoprostanes (markers of oxidative stress) in humans with alcohol-induced liver disease.

For more information on vitamin C, see the Linus Pauling Institute's Micronutrient Information Center.

Last updated November, 1999

Honoring a Scientific Giant with Nutritional Research Toward Longer, Better Lives

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