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M. B. ZEMEL, Dept. of Nutrition, Univ. of Tennessee, 1215 W. Cumberland Ave., Knoxville, TN 37996-1920 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 over-consumption of an energy-dense diet and to increase lipolysis and preserve thermogenesis during caloric restriction, thereby markedly accelerating weight loss. Our studies of human adipocyte metabolism demonstrate a key role for intracellular Ca2+ in regulating lipid metabolism and triglyceride storage, with increased intracellular Ca2+ resulting in stimulation of lipogenic gene expression and lipogenesis and suppression of lipolysis, resulting in adipocyte lipid filling and increased adiposity. Moreover, the increased calcitriol produced in response to low calcium diets stimulates adipocyte Ca2+ influx and, consequently, promotes adiposity, while higher calcium diets inhibit lipogenesis, promote lipolysis, lipid oxidation and thermogenesis and inhibit diet-induced obesity in mice. Notably, dairy sources of calcium exert markedly greater effects in attenuating weight and fat gain and accelerating fat loss. This augmented effect of dairy products versus supplemental calcium is likely due to additional bioactive compounds, such as angiotensin converting enzyme (ACE) inhibitors in dairy, as well as the rich concentration of branched chain amino acids, which act synergistically with calcium to attenuate adiposity. These concepts are confirmed by epidemiological data as well as recent clinical trials which demonstrate that diets which include at least three daily servings of dairy products result in significant reductions in adipose tissue mass in obese humans in the absence of caloric restriction and markedly accelerates the weight and body fat loss secondary to caloric restriction compared to low dairy diets. These data indicate an important role for dairy products in both the prevention and treatment of obesity.
Session 70, A role of dairy foods in weight management
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