The efficacy of vitamin C supplementation on reducing total serum cholesterol in human subjects: a review and analysis of 51 experimental trials.
OBJECTIVE
Observational studies in humans have shown an inverse relationship between plasma vitamin C concentration and total serum cholesterol. However, experimental studies have shown inconsistent results regarding the ability of vitamin C to reduce total serum cholesterol.


METHODS
Published reports of trials studying the effects of vitamin C on serum lipids were identified by a search of Medline from 1966 to 2004. Data from 51 experimental studies comprising of 1666 pooled subjects were selected for analysis.


RESULTS
A very strong negative association was observed between baseline total serum cholesterol and the percent change in cholesterol (r = -0.585, p<0.001). When subjects were divided into 4 groups based on their baseline total serum cholesterol levels, the following weighted mean percent changes in cholesterol from baseline were observed: normal cholesterol (<199mg/dl): 0.91+/-6.8% (n=508); borderline high cholesterol (200-239mg/dl): 3.90+/-5.78% (n=605); high cholesterol (240-279mg/dl): 11.40+/-7.96% (n=300); severe cholesterol (>280mg/dl): 14.30+/-8.36% (n=253). A significant inverse relationship was found between the baseline plasma vitamin C concentrations and mean percent change in total cholesterol from baseline (r = -0.500, p<0.005). It was also observed that the high and severe baseline cholesterol groups possessed lower baseline plasma vitamin C concentrations than those in the normal cholesterol groups (0.79 and 0.55 versus 1.24 mg/dl respectively).


CONCLUSIONS
This finding strengthens the hypothesis that the cholesterol lowering and cardio-protective benefit of vitamin C supplementation may be in its ability to elevate plasma vitamin C concentrations in those patients who initially possess lower than normal vitamin C plasma concentrations.
McRae
Marc P
MP
Department of Physiology and Biochemistry, National University of Health Sciences, Lombard, IL.
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