High Dietary Calcium Reduces Body Fat Content, Digestibility of Fat, and Serum Vitamin D in Rats

TLDR

The study examined which energy‑balance factor drives reduced body fat in rats on a high‑calcium, high‑dairy‑protein diet. Male Wistar rats were fed either a control diet (25 % kcal fat, 14 % kcal protein from casein, 0.4 % calcium) or a high‑calcium diet (25 % kcal fat, 7 % kcal protein from nonfat dry milk, 7 % kcal protein from casein, 2.4 % calcium) for 85 days, and researchers measured body weight, energy intake and expenditure, rectal temperature, body composition, and serum metabolites. Rats on the high‑calcium diet gained 29 % less carcass fat, had 90 % of gross energy digestible versus 94 % in controls due to increased fecal lipid excretion, and showed 23 % lower serum triglycerides and 86 % lower 1,25‑dihydroxyvitamin D, with no difference in body temperature or energy expenditure.

Abstract

Abstract Objective : This study investigated which aspect of energy balance was responsible for the decrease in body fat content of rats fed a high‐calcium, high—dairy protein diet. Research Methods and Procedures : Male Wistar rats were fed a control diet (25% kcal fat, 14% kcal protein from casein, 0.4% by weight calcium) or high‐calcium diet (25% kcal fat, 7% kcal protein from nonfat dry milk, 7% kcal protein from casein, 2.4% calcium) for 85 days. Body weights, digestible energy intakes, energy expenditures, rectal temperatures, body composition, and serum glucose, insulin, free fatty acids, triglycerides, and 1, 25‐dihydroxyvitamin D were measured. Results : Rats fed high‐calcium diet gained significantly less weight than controls and had 29% less carcass fat. Gross energy intake was not significantly different between groups, but digestible energy was 90% of gross energy in the high‐calcium diet compared with 94% in the control diet because of increased fecal excretion of dietary lipid. The difference in digestible energy intake accounted for differences in carcass energy. Body temperatures and energy expenditures of the rats were not different. The high‐calcium diet reduced serum triglycerides by 23% and serum 1, 25‐dihydroxyvitamin D by 86%. Discussion : These results confirm that a high‐calcium diet decreases body weight and fat content due to a lower digestible energy intake caused by increased fecal lipid and a nonsignificant reduction in gross energy intake.