Vitamin C and Cholesterol Reduction

VITAMIN C INTAKE AND HDL CHOLESTEROL REDUCTION

Vitamin C intake has been positively correlated with a reduced incidence of cardiovascular disease in several epidemiological studies. This has usually been attributed to the fact that high plasma concentrations of vitamin C are associated with low levels of plasma cholesterol, and vitamin C's direct relationship with the desirable high-density lipoprotein (HDL) cholesterol. While vitamin C deficiency has clearly been shown to cause hypercholesterolemia, the relationship of vitamin C to cholesterol in persons ingesting adequate amounts of vitamin C has been unclear.

Researchers from the USDA and National Institute on Aging conducted a recent trial on participants in the Baltimore Longitudinal Study of Aging. This study investigated the effect of vitamin C intake on total cholesterol levels and its fractions. The researchers found that in a well-nourished population with vitamin C intake well above the RDA of 60 mg/day, and with adequate concentrations of plasma vitamin C, there was a significant positive association between high levels of plasma vitamin C and high levels of HDL cholesterol. In summary, after adjustment for age, sex, obesity, and smoking, high plasma vitamin C was directly associated with high HDL cholesterol.

In the words of the authors, "Our research suggests that even in a population consuming two to three times the RDA of ascorbic acid, less atherogenic profiles can be seen in those with higher plasma concentrations of ascorbic acid." Thus, it appears likely that the RDA for vitamin C is inadequate to maintain plasma vitamin C at levels that have a positive influence on HDL cholesterol levels and that lower the risk of cardiovascular disease.

Peak plasma concentrations of vitamin C occurred at intakes of approximately 215 mg/day in women and 345 mg/day in men. Further increases in plasma vitamin C did not occur with higher intakes. Therefore, the research also indicated the apparent upper limits of vitamin C intake that are required to produce peak plasma concentrations, and to achieve maximum effect on HDL levels.

Reference

J. Hallfrisch, V.N. Singh, D.C. Muller, et al. Am J Clin Nutr. 1994;60:100-105.

The information in this article is not intended to provide personal medical advice, which should be obtained from a medical professional, and has not been approved by the U.S. FDA.

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