Serum retinol levels throughout 2 years of cholesterol-lowering therapy

Some studies have reported an inverse correlation between serum cholesterol level and risk of cancer. This correlation might be due to a decrease in serum retinol, a lipid-soluble vitamin that controls cell proliferation and differentiation. We evaluated the influence of cholesterol-lowering therapy on serum retinol in 102 subjects (mean ± SE: aged 47.1 ± 4.1 years; body mass index, 23.8 ± 0.6 kg/m 2) with primary hypercholesterolemia treated for 2 years with different therapeutic protocols. Twenty-two subjects had been treated with diet alone, 35 with diet and fibrates, 37 with diet and hepatic hydroxymethyl glutaryl coenzyme A (HMG CoA) reductase inhibitors (statins), and eight with diet and cholestyramine. Postabsorptive serum retinol, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride levels were determined at baseline and every 3 months. Baseline TC and LDL-C were significantly, lower in the diet-treated group than in other groups. No intergroup differences were found in pretreatment levels of triglycerides and serum retinol. After 2 years of treatment, TC and LDL-C serum levels were not significantly decreased in the diet-alone group, whereas they were decreased by 20% and 24%, respectively, in the gemfibrozil group, 28% and 34% in the statins group; and 21% and 27% in the cholestyramine group. In the entire population (N = 102), serum retinol was 3.46. ± 0.08 μmol/L before therapy and 3.76 ± 0.07 after 2 years of therapy ( P < .001). Serum retinol increased in diet- and statin-treated groups, but not in fibrate- and resin-treated groups. Serum retinol-binding protein ([RBP] n = 37 subjects) was unchanged after the 2-year cholesterol-lowering therapy (50.6 ± 3.2 mg/L before and 50.9 ± 2.8 after, P = NS). In the pooled data, changes in serum cholesterol and retinol were unrelated to each other ( r = .053, P = .60). Our data suggest that (1) long-term hypocholesterolemic therapy does not decrease serum retinol levels; (2) prolonged dietary treatment of hypercholesterolemia increases serum retinol levels; and (3) this diet-dependent effect is counteracted by combined fibrate or resin, but not statin, treatment.