Chromium supplementation has been demonstrated to improve insulin sensitivity in some, but not all, studies conducted in insulin-resistant subjects. Chromium has also been suggested to have effects to improve plasma lipid profiles. In this application we propose a study to examine the long-term (1 year) effects of chromium supplementation to prevent or attenuate the progression of insulin resistance and dyslipidemia in a nonhuman primate model of the Metabolic (insulin resistance) Syndrome. The development of insulin resistance in obese rhesus monkeys shares similar features with the progression of metabolic disease in humans. We have previously demonstrated that providing obese rhesus monkeys with a sugar-sweetened beverage daily in combination with ad libitum access to their normal diet for 1 year results in modest weight and body fat gain accompanied by a rapid progression of insulin resistance and dyslipidemia (elevated triglyceride and reduced HDL levels). The use of this model in which rigorous control and compliance with diet and chromium intake can be ensured will allow us to determine the effects of long-term chromium supplementation in the progression of the metabolic syndrome. In addition, we will assess the effects of chromium on a number of lipid and inflammatory parameters associated with insulin resistance and cardiovascular risk including apolipoprotein-B, lipoprotein particle size, adiponectin, C-reactive protein, homocysteine, interleukin-6, tumor necrosis factor-alpha, and PAl-1. We will also determine the effects of chromium on two parameters closely linked to muscle insulin action; muscle triglyceride content and whole body substrate oxidation (respiratory quotient). Although chromium picolinate is the most widely used form of chromium supplement, some studies suggest that the nicotinate form of chromium is more bioavailable and therefore more effective. Therefore, we will compare the bioavailability (tissue chromium status) and the efficacy of chromium picolinate and chromium nicotinate in the amelioration of diet-induced insulin resistance and dyslipidemia. The results of these studies will provide valuable information for the design and implementation of new clinical studies examining the effects of chromium supplements in the management of metabolic syndrome in humans.
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