Effects of Dietary Calcium on Body Composition and Lipid Metabolism in Rats

Abstract

Calcium (Ca) intakes may affect cardiovascular disease risk by altering body weight/fat and serum lipid profile, but results have been inconsistent and the underlying mechanisms are not well understood. Thus, the effects of dietary Ca on body composition and lipid metabolism were examined in male Sprague-Dawley rats. Rats were fed high-fat, high-energy diets containing (g/kg) low (0.75Ca, 0.86 ± 0.05; 2Ca, 2.26 ± 0.02), normal (5Ca, 5.55 ± 0.08) or high (10Ca,11.03 ± 0.17; 20Ca, 21.79 ± 0.15) Ca for 10 weeks. At the end of the study the 0.75Ca group had lower (p < 0.05) body weight and fat mass compared to other groups. Rats fed the high Ca diets had lower serum total and LDL cholesterol compared to rats fed normal or low Ca. Liver total cholesterol was lower in rats fed high compared to low Ca. In general, liver mRNA expression of the LDLR and genes involved in cholesterol synthesis (HMGCR and HMGCS1), fatty acid oxidation (CPT2) and cholesterol esterification (ACAT2) were higher in rats fed higher Ca. Apparent digestibility of total trans, saturated, monounsaturated and polyunsaturated fatty acids was lower in rats fed the high compared to the low Ca diets, but the differences were greatest for trans and saturated fatty acids. Fecal excretion of cholesterol and total bile acids was highest in rats fed the 20Ca diet. The results suggest little effect of dietary Ca on body composition unless Ca intakes are very low. Decreased bile acid reabsorption and reduced absorption of neutral sterols and trans and saturated fatty acids may contribute to the improved serum lipid profile in rats fed higher Ca.