Most of the interest in calcium has revolved around bone health, being positively related to bone mineral density in both adolescent boys and girls and adult men and women. However, recent interest in calcium has focused on its potential to influence body fat.
A study examined the relationship between food consumption and body composition in preschool children over a period of 2 to 96 months. Detailed dietary intakes were obtained using in-home interviews and body composition was assessed using dual-energy X-ray absorptiometry. Calcium intake and total servings of dairy products were negatively related to body fat independent of body mass index (i.e., higher calcium intakes were associated with lower body fat). Analysis of NHANES III data indicated that the odds ratio of being in the highest quartile of body fat was significantly reduced for the highest quartile of calcium intake and decreased in a dose response fashion for the second, third, and fourth quartiles, respectively.
Another study demonstrated that transgenic mice consuming a high-calcium diet (either calcium supplements or medium- and high-dairy diets) exhibited less body fat accumulation, increased lipolysis (fat breakdown), and decreased lipogenesis (fat synthesis) compared to mice on a low-calcium diet equal in energy. It is believed that dietary calcium may have this effect on fat breakdown by altering calcitrophic hormones and calcium influx into fat cells (i.e., increased dietary calcium should suppress calcitrophic hormones and therefore reduce intracellular calcium and lipid storage).
In line with these findings, our laboratory recently showed that adolescent boys who supplemented their diets with 3 servings/day of 1% fluid milk demonstrated greater fat loss compared to a group who supplemented with juice. Collectively, several lines of evidence indicate that calcium, and/or some other component of milk/dairy products, reduces obesity risk probably by enhancing the breakdown of fat.