Written by Dr. Vijaya Juturu, Nutrition 21, USA. Conference paper presented at the American Oil Chemists Society (AOCS) Annual Meeting & Expo, May 2004. Theme: Cost-Effective Methods to Address the Leading Causes of Death & Chronic Diseases
IR occurs when the body does not respond properly to insulin, and contributes to reduced glucose uptake in muscle cells and enhanced free fatty acid production. Chromium (Cr) is an essential trace element required for normal insulin function in order to maintain glucose homeostasis and regulate carbohydrate, protein and lipid metabolism. Research has shown an inverse relationship between Cr tissue levels and the prevalence of diseases related to IR, such as type 2 diabetes (DM) and coronary heart disease (CHD). Recent studies have shown that Cr supplementation can help restore normal insulin sensitivity and reduce insulin resistance syndrome (IRS) risk factors. A number of mechanisms by which Cr enhances insulin function have been identified throughout the insulin-signaling pathway (ISP). Cr may contribute to the normal metabolic actions of the insulin receptor, insulin receptor substrate (IRS), PI 3-kinase, PTP1B Akt proteins and GLUT 4 transporters. Studies using chromium picolinate (CrPic) have shown that Cr is involved in the intermediate steps of the ISP and regulates the activity of downstream proteins involved in cellular physiology. Studies have also shown that Cr increases the activity of insulin binding, insulin receptor phosphorylation, PI3 kinase activity, Akt phosphorylation and GLUT-4 translocation and decreases PTP1B and GSK3 activity. Pre-clinical and clinical CrPic supplementation studies have shown enhancement in glucose uptake and glycogen synthesis, as well as decreases in glycosylated hemoglobin, blood glucose and insulin levels. In addition, one of the metabolic events induced by glucose stimulation appears to be a relative shift from fatty acids to glucose as an oxidative fuel. Fatty acids (FAs) may enhance insulin resistance and associated risk factors. Concomitant administration of chromium picolinate (CP) with FAs may reduce the risk of insulin resistance. Taken together, these studies suggest that chromium as CrPic supplementation can be used as a nutritional therapy to reduce insulin resistance, restore normal glucose metabolism, and possibly prevent conditions associated with IR. Additional studies are needed to define the cellular mechanisms of Cr and its impact on IR.
