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Introduction & Objective: Calcium is a micronutrient and now receiving much attention for its doubtful effects on weight and body fatness. A few mechanisms has been suggested for calcium effects on body fatness and the most emphasized one is the reducing of lipolysis and increasing lipogenesis via reducing parathyroid hormone levels. The present study is designed to evaluate the effects of nondairy dietary calcium on adipogenesis and adipocyte size in male Sprague dawley rats. Materials & Methods: This experimental study was done from November to September of 2005 at Tehran school of health, nutrition department. 48 male Spragu-Dawley rats from Damgostar Company were used in three randomly selected groups. The rats were fed low (0.2% W/W), usual (0.5% W/W) and high (1.2% W/W) dietary calcium based on AIN-93M purified diet. Rats were housed in 12 hours light-dark cycle, 22-25°C room temperature with free access to their respective diets. At the end of the experiment, rats were decapitated and carcass fat content, carcass ash content and mean adipocyte size in testis, peritoneal and subcutaneous fat pads were compared in three groups. The SPSS 11.5 was used as statistical software, running analysis of variance for comparing the effects. Results: weight gain, carcass fat content and adipocyte size, in groups were not significantly different, while serum parathyroid hormone concentrations in high calcium group was significantly lower than low calcium group (p<0.05) and insignificantly lower than usual calcium group [12.36, 23.57 and 42.2 pg/dl respectively]. Serum concentrations of 25-hydroxy cholecalciferol were also insignificantly lower in high calcium group. Conclusion: Our findings suggested that physiological concentration of dietary calcium is not effective on weight gain, body fatness and adipocyte size. Relatively equal fat content beside significant difference in serum parathyroid hormone levels is against the parathyroid theory of calcium effects on body fatness. Finally we do not suggest any effect for calcium on body fatness and adipocyte size.

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ABSTRACT: Introduction & Objective: There are different methods for improving hypercholesterolemia, insulin resistance and hypertriglyceridemia, the major risk factors of cardio-vascular disease. Calcium, a nutrient essential for many vital functions of the body is now receiving much attention for its possible hypolipidemic effects. The large bodies of studies on the effects of calcium on the serum lipids have shown conflicting results and also there is little evidence for its effects on serum insulin and glucose. Materials & Methods: In this study, the researchers evaluated the effects of three levels of dietary calcium (0.2, 0.5 and 1.2 gram% diet) on serum cholesterol, HDL-cholesterol, LDL-Cholesterol and serum insulin and glucose in male Sprague-Dawley rats. The amount of fecal fat excretion was measured to determine the possible mechanism of lipid lowering effects of calcium. Results: Findings showed that increasing dietary calcium lowerd the serum cholesterol (p=0.04), LDL-cholesterol (p=0.02) but had no significant effects on HDL-cholesterol, serum insulin and glucose. There was a dose dependent increase in fecal fat excretion but was not statistically different on a percent basis. Conclusion: It can be concluded that calcium is an effective hypocholesterolemic nutrient but its effects on serum triglycerids, glucose and insulin need to be evaluated.