48-5 |
Body weight and growth regulation: Does dairy play a role? |
M. B. ZEMEL, Dept. of Nutrition, Univ. of Tennessee, 1215 W. Cumberland Ave., Knoxville, TN 37996-1900 Dietary calcium plays a pivotal role in the regulation of energy metabolism, as we have found high calcium diets to attenuate adipocyte lipid accretion and weight gain during periods of overconsumption of an energy-dense diet and to increase lipolysis and preserve thermogenesis during caloric restriction, thereby markedly accelerating weight loss. Our studies of the agouti gene in obesity and insulin resistance demonstrate a key role for intracellular Ca 2+ in regulating adipocyte lipid metabolism and triglyceride storage, with increased intracellular Ca 2+ resulting in stimulation of lipogenic gene expression and lipogenesis and suppression of lipolysis, resulting in lipid filling and increased adiposity. Moreover, we have recently demonstrated that the calcitrophic hormones which respond to low calcium diets stimulate Ca2+ influx in human adipocytes and thereby promote adiposity. Accordingly, suppressing calcitriol levels by increasing dietary calcium is an attractive target for the prevention and management of obesity. In support of this concept, transgenic mice expressing the agouti gene specifically in adipocytes (a human-like pattern) respond to low calcium diets with accelerated weight gain and fat accretion, while high calcium diets markedly inhibit lipogenesis, accelerate lipolysis, increase thermogenesis and suppress fat accretion and weight gain in animals maintained at identical caloric intakes. Further, low calcium diets impede body fat loss, while high calcium diets markedly accelerate fat loss in transgenic mice subjected to caloric restriction. These findings are further supported by clinical data demonstrating that increasing dietary calcium results in significant reductions in adipose tissue mass in obese humans as well as by NHANES III data demonstrating a profound reduction in the odds of being obese associated with increasing dietary calcium intake. Notably, dairy sources of calcium exert a significantly greater anti-obesity effect than supplemental sources in each of these studies, indicating an important role for dairy products in the control of obesity.
Session 48, Dairy foods: More than just good nutrition
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