Lipid profiles of rats fed with diets supplemented with vitamins niacin and pyridoxine

Hypercholesterolemia is a major risk factor for cardiovascular disease. Supplements containing the vitamins niacin (B3) and pyridoxine (B6) can promote the reduction of total cholesterol and an increase in HDL cholesterol. In this study, the effects of diets supplemented with niacin (B3) and pyridoxine (B6) on the hepatic and serum lipid profiles of Wistar rats were assessed. The diets were prepared with combinations of three concentrations of niacin (3, 4 and 5 g/kg) and pyridoxine (6, 12 and 18 mg/kg) and one with neither vitamin. The animals were divided into eleven experimental groups of six animals per group, and nine groups were fed on a standard diet with 7.5% fat and vitamin supplementation. Another group was fed with 7.5% fat without vitamin supplements. A control group received the standard diet (AIN-93M) without modifications (4% fat). The weight gain, food intake, serum and hepatic total cholesterol, serum cholesterol fractions (HDL, LDL, and VLDL), serum and hepatic triacylglycerols and hepatic and fecal lipid contents were measured after 30 days. The diet with the highest concentration of niacin and lowest concentration of pyridoxine had the lowest level of total hepatic cholesterol. Hepatic triacylglycerols were reduced by the highest concentration of niacin (5 g/kg), and this reduction was enhanced by increasing the pyridoxine concentration. The diets supplemented with niacin and pyridoxine reduced the levels of serum total cholesterol, LDL, VLDL, triacylglycerols and hepatic lipids. These effects on the lipid profile varied with the concentrations of the two vitamins and the interactions between them.