Loss of chromium occurs during long periods of stress such as pregnancy, infection, physical trauma, and strenuous exercise. Several animal experiments have also demonstrated that high sucrose, chromium deficient diets potentially cause severe atherosclerosis. This exacerbates the problem, since these foods are not only low in chromium but they also induce enhanced excretion of chromium in the urine. Chromium deficient diets are characterised by large quantities of refined foods, especially simple sugars. This can lead to impaired insulin function, inhibition of protein synthesis and energy production and ultimately to type 2 diabetes and cardiovascular dysfunction. Many individuals such as athletes, diabetics, pregnant women, and the elderly are especially at risk of chromium deficiency. 8 Chromium deficiency is a widespread problem. However, an individual should consume between 30 and 200 micrograms to fulfill that requirement due to its poor absorption. The daily requirement for chromium is about one microgram per day. Chromium might have biological activity through regulating gene expression in some manner, since it was found to up-regulate genes encoding proteins involved in glycolysis in a study on obese mice. Chromium upregulates mRNA levels of the insulin receptor GLUT4, however this may be occurring through the amplification of insulin, which also increases mRNA. It is suggested that it does this through affecting AMP-activated protein kinase. 3Ĭhromium was also found to alter plasma membrane cholesterol. This transfer is likely mediated by the metal transport protein transferrin. Increases in plasma insulin concentrations have been found to result in a movement of chromium from the blood to insulin-dependent cells. ![]() 2 In response to increases in blood sugar levels, insulin is released rapidly into the bloodstream. 7Ĭhromium affects many processes of the insulin signaling pathway. 3 Tyrosine kinases are important mediators of the signaling cascade, determining key roles in diverse biological processes like growth, differentiation, metabolism and apoptosis in response to external and internal stimuli. 2 The newly generated holochromodulin (i.e., Cr4-chromodulin) can then bind to the insulin-stimulated insulin receptor, helping to maintain its active conformation and amplifying the receptors kinase activity. 3 Apochromodulin (the predominant form in vivo) can accept chromic ions from other biological molecules such as transferrin, to form holochromodulin. In the 1980’s a unique chromium-binding oligopeptide called chromodulin was isolated and characterized, with the ability to potentiate the effects of insulin, without changing its concentration. In the 60 years since chromium’s role in blood sugar regulation was suggested, little progress has been made in establishing its nutritional requirement and biochemistry. 2 Many studies report that chromium is decreased in diabetes patients, and insulin resistance is improved by the supplementation of chromium. Studies have shown that chromium supplements in chemical forms such as picolinate, proprionate, niacinate, histadinate, and malate in therapeutic amounts can consistently alleviate insulin resistance and diabetes and associated changes in carbohydrate and lipid metabolism. 2 However, the controversy over chromium’s essentiality does not preclude it being considered a bioactive element with beneficial effects when supplemented. With this definition in mind, the essentiality of chromium has been disputed. A dietary deficiency of the element has to consistently impair a biochemical or physiological function that could be prevented or reversed by nutritional or physiological intakes of the element. The definition of an essential element is when ‘a deficiency causes interference with growth, development, or maturation, such that procreation is prevented’. As recently as 1989 the Food and Nutrition Board recognized that ‘trivalent chromium is required to maintain normal glucose metabolism in laboratory animals it acts as a cofactor for insulin.’ 2 The first major research on chromium in the early 1960s concluded that chromium was an essential element for humans. Chromium is a biologically active element that is at its highest in body tissue at birth and declines with age. 8 It is widely distributed in the atmosphere, soil, water, animals and plants in the form of chromite. ![]() 1 The human body’s total content is approximately 6 milligrams. Chromium is the eighth largest classical element in the earth’s crust.
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