Recent advances in the nutritional biochemistry of trivalent chromium

Abstract

The nutritional biochemistry of trivalent Cr has been a poorly understood field of study; investigations of the biochemistry of the other essential transition metals have not proven as problematic. Despite over four decades of endeavour, only recently has a picture of the role of Cr potentially started to be defined. The biologically-relevant form is the trivalent ion. Cr3+appears to be required for proper carbohydrate and lipid metabolism in mammals, although fortunately Cr deficiency is difficult to achieve. Conditions that increase circulating glucose and insulin concentrations increase urinary Cr output. Cr is probably excreted in the form of the oligopeptide chromodulin. Chromodulin may be the key to understanding the role of Cr at a molecular level, as the molecule has been found to bind to activated insulin receptor, stimulating its kinase activity. A mechanism for the action of chromodulin has recently been proposed; this mechanism can serve as a potential framework for further studies to test the role of Cr in metabolism. An examination of the nutritional supplement chromium picolinate illustrates some of the difficulties associated with these biochemical studies.

Tissue accumulation and urinary excretion of chromium in rats fed diets containing graded levels of chromium chloride or chromium picolinate

“…Trivalent chromium (Cr) is an essential trace element for human and animal nutrition (Mertz, 1993) and enhances insulin function in the form of a low molecular weight Cr binding substance (LMWCr), called chromodulin (Vincent, 2004). Severe Cr deficiency induces impaired glucose tolerance and is believed to increase the risk for diabetes (Mertz, 1969).…”

Mass Spectrometry Analysis of Chromium-Binding Low-Molecular-Weight Serum Fractions

“…The major factor that causes Cr(III) to be regarded as an essential element is its purported function in carbohydrate and lipid metabolism through its interaction with insulin [1][2][3][4]. However, the acceptance of Cr(III) as an essential element for humans and animals is now widely controversial since specific chemical mechanisms and the biologically active form by which Cr(III) carries out its insulin potentiating activities has not been found yet [5,6].…”

Evaluation of insulin binding and signaling activity of newly synthesized chromium(III) complexes in vitro

“…However, recent studies have questioned the safety of certain supplemental trivalent Cr complexes (26). Comparative studies of chromium(III) picolinate and niacin-bound chromium(III), two popular dietary supplements, have revealed that chromium(III) picolinate produces significantly more oxidative stress and DnA damage (27)(28)(29)(30). Recently, chromium picolinate has been shown to be mutagenic in some in vitro tests, and picolinic acid moiety appears to be responsible for that effect (27) 3 ] + cation has been studied and proposed as an alternative supplemental source of Cr.…”