SERUM RETINOL LEVELS THROUGHOUT 2 YEARS OF CHOLESTEROL-LOWERING THERAPY

Some studies have reported an inverse correlation between serum choles terol level and risk of cancer. This correlation might be due to a dec rease in serum retinol, a lipid-soluble vitamin that controls cell pro liferation and differentiation. We evaluated the influence of choleste rol-lowering therapy on serum retinol in 102 subjects (mean +/- SE: ag ed 47.1 +/- 4.1 years; body mass index, 23.8 +/- 0.6 kg/m(2)) with pri mary hypercholesterolemia treated for 2 years with different therapeut ic protocols. Twenty-two subjects had been treated with diet alone, 35 with diet and fibrates, 37 with diet and hepatic hydroxymethyl glutar yl coenzyme A (HMG CoA) reductase inhibitors (statins), and eight with diet and cholestyramine. Postabsorptive serum retinol, total choleste rol (TC), high-density lipoprotein cholesterol (HDL-C), low-density li poprotein cholesterol (LDL-C). and triglyceride levels were determined at baseline and every 3 months. Baseline TC and LDL-C were significan tly lower in the diet-treated group than in other groups. No intergrou p differences were found in pretreatment levels of triglycerides and s erum retinol. After 2 years of treatment, TC and LDL-C serum levels we re not significantly decreased in the diet-alone group, whereas they w ere decreased by 20% and 24%, respectively, in the gemfibrozil group, 28% and 34% in the statins group; and 21% and 27% in the cholestyramin e group. In the entire population (N = 102), serum retinol was 3.46 +/ - 0.08 mu mol/L before therapy and 3.76 a +/- 0.07 after 2 years of th erapy (P < .001). Serum retinol increased in diet and statin-treated g roups, but not in fibrate and resin-treated groups. Serum retinol-bind ing protein ([RBP] n = 37 subjects) was unchanged after the P-year cho lesterol-lowering therapy (50.6 +/- 3.2 mg/L before and 50.9 +/- 2.8 a fter, P = NS). In the pooled data, changes in serum cholesterol and re tinol were unrelated to each other (r = .053, P = .60). Our data sugge st that (1) long-term hypocholesterolemic therapy does not decrease se rum retinol levels; (2) prolonged dietary treatment of hypercholestero lemia increases serum retinol levels; and (3) this diet-dependent effe ct is counteracted by combined fibrate or resin, but not statin, treat ment. Copyright (C) 1995 by W.B. Saunders Company