Effect of vitamin C supplementation on lipoprotein cholesterol, apolipoprotein, and triglyceride concentrations.

Plasma ascorbic acid (AA) frequently is positively correlated with high-density-lipoprotein (HDL) cholesterol and inversely related to total cholesterol concentration. To determine if vitamin C intake can alter cholesterol concentration, we examined the effect of vitamin C supplementation (1 g/d) on lipoprotein cholesterol and triglyceride levels in 138 subjects, aged 20 to 65 years, who completed an 8-month randomized, double-blinded, placebo-controlled trial. Individuals with higher levels of plasma AA (> 80 mumol/L for men and > 90 mumol/L for women), HDL cholesterol (> 1.4 mmol/L for men and > 1.7 mmol/L for women), and total cholesterol (> 6.7 mmol/L) were excluded from this trial. We observed no overall effect of supplementation on plasma concentrations of HDL, LDL, or total cholesterol, apolipoprotein (apo) B, or triglyceride. We did observe a marginally significant (P < 0.10) increase of 1.9 mumol/L (5.3 mg/dL) in apo A-I concentration with supplementation and a significant (P < 0.05) difference of 0.10 mmol/L (3.8 mg/dL) in HDL cholesterol concentration between vitamin C and placebo treatment in a nonrandomized subgroup of individuals (n = 43) and a baseline plasma AA level less than 55 mumol/L. Although the apo A-I concentration increase was only marginally significant with supplementation, change in plasma AA concentration was significantly (P < 0.05) correlated with change in apo A-I concentration in the entire sample. The overall results of this trial were negative, but our data do not allow us to rule out the possibility that vitamin C supplementation might increase HDL cholesterol or apo A-I concentrations among individuals with lower plasma AA levels.