High-calcium diet with whey protein attenuates body-weight gain in high-fat-fed C57B1/6J mice

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)-D-3) and decreases fat absorption. We studied the effect of Ca and milk proteins (whey and casein) on body weight in C57B1/6J 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 (SENT 0.2) % in the low-Ca casein group; P<0.05), which may partly explain the effect on body weight.