High-calcium diet with whey protein attenuates body-weight gain in high-fat-fed C57Bl/6J mice

Abstract

An inverse relationship between Ca intake and BMI has been found in several studies. It has been suggested that Ca affects adipocyte metabolism via suppressing 1,25-dihydroxycholecalciferol (1,25(OH)2-D3) and decreases fat absorption. We studied the effect of Ca and milk proteins (whey and casein) on body weight in C57Bl/6J mice. Male mice, age 9 weeks, were divided into three groups (ten mice per group) receiving modified high-fat (60 % of energy) diets. Two groups received a high-Ca diet (1·8 % calcium carbonate (CaCO3)), with casein or whey protein (18 % of energy), and one group received a low-Ca diet (0·4 % CaCO3) with casein for 21 weeks. Food intake was measured daily and body weight twice per week. Body fat content (by dual-energy X-ray absorptiometry) of all mice and faecal Ca and fat excretion of seven mice/group were measured twice during the study. Final body weight (44·1 (sem 1·1) g) and body fat content (41·6 (sem 0·6) %) were significantly lower (P < 0·05) in the high-Ca whey group than in the low-Ca casein group (48·1 (sem 0·8) g and 44·9 (sem 0·8) %). Body weight and body fat content of the high-Ca casein group did not differ significantly from the low-Ca casein group even though serum 1,25(OH)2-D3 levels were significantly lower (P < 0·001) in both high-Ca groups than in the low-Ca casein group. Thus changes in serum 1,25(OH)2-D3 do not seem to affect body weight in this animal model. There was a significant difference in fat excretion between the high-Ca whey and low-Ca casein groups (3·9 (sem 0·9) % in the high-Ca whey v. 1·4 (sem 0·2) % in the low-Ca casein group; P < 0·05), which may partly explain the effect on body weight.