Chromium glucose tolerance factor

Glucose tolerance factor chromium in 888 Glucose transporters 415, 416 GLUT1, topology diagram 416 GLUT4, response to insulin 416 Glucosidase... 

Total dietary Chromium, uncertain amount of which is "glucose tolerance factor" chromium. 

Brewers and bakers dried yeasts are used as dietary supplements. They contribute some protein and trace minerals, and some B vitamins, but no vitamin C, vitamin B 2 or fat-soluble vitamins. The glucose tolerance factor (GTE) of yeast, chromium nicotinate, mediates the effect of insulin. It seems to be important for older persons who caimot synthesize GTE from inorganic dietary chromium. The ceU wall fraction of bakers yeast reduces cholesterol levels in rats fed a hypercholesteremic diet. 

Chromium deficiency may be related to the glucose tolerance factor (Herold and Fitzgerald 1994). The determination of this deficiency, however, is questioned, because the lack of accuracy of the Cr determination in the earlier publications. 

Chromium was recognized as an essential trace element in 1955.1190 Rats fed a chromium-deficient diet developed an impaired tolerance for intravenous glucose, which could be reversed by an insulin-potentiating factor present in brewer s yeast, meat and various other foods. The insulin-potentiating factor was found to be a complex of chromium(IH)1191 and such substances have been termed Glucose Tolerance Factor(s) (GTFs). Chromium was demonstrated to be essential for humans in 1975.1192 There are several reviews of the chemistry of chromium(III) and its relationship to glucose tolerance.1193-1196... 

Finally, it should be noted that this chemistry may have biological relevance. Several metalloenzymes are believed to contain more than one metal ion bound at the active site. One relevant example is the glucose tolerance factor (GTF) which is important for the metabolic degradation of glucose (398-401). GTF is a low-molecular-weight protein which contains chromium(III). Its structure is not known, but it has been suggested that the active site contains a dinuclear chromium(III) complex (401). The fact that hydroxo-bridged dinuclear chromium(III) complexes exhibit reactions which are often very fast compared with those observed for the parent mononuclear species seems to support such a proposal. 

Chromium was proposed as an essential element after the observation that rats fed with Torula yeast developed impaired glucose tolerance.1085 The active ingredient in other yeasts was suggested to be a chromium complex, named the glucose-tolerance factor . Brewers yeast contains chromium in the range 0.35-5.4 xgg-1.1086... 

In humans and animals, chromium(ni) is an essential nutrient that plays a role in glucose, fat, and protein metabolism by potentiating the action of insulin (Anderson 1981). The biologically active form of chromium, called glucose tolerance factor (GTF), is a complex of chromium, nicotinic acid, and possibly amino acids (glycine, cysteine, and glutamic acid). Both humans and animals are capable of converting... 

Chromium This metal is essential for normal insulin and glucose function. Chromium is involved in the glucose tolerance factor affecting insulin and the clearance of glucose from the body [14, 15],... 

Nicotinic acid has been tentatively identified as the organic component of the (as yet uncharacterized) chromium-containing glucose tolerance factor that enhances the interaction of insulin with cell surface receptors. 

The bio-availabilities of these elements through the gastrointestinal tract vary markedly. Molybdenum, iodine, fluorine, and arsenic are apparently highly bio-available, whereas medium uptake occurs with haem iron, cobalt, zinc, chromium in the presence of a glucose tolerance factor, selenium, either as selenate or as organo selenium compounds, whereas only low bio-availability is experienced with non-haem iron,... 

Chromium (III), on the other hand, is an essential trace metal in mammalian nutrition, aiding in the metabolism of glucose see Nutritional Aspects of Metals Trace Element. The adequate intake of chromium has been estimated as 25-35pgday The glucose tolerance factor (GTF) is a chromium containing extract of brewer s yeast, which enhances the action of insulin. There is no evidence for any toxic effects of Cr. ... 

C. M. Murdoch, Ph.D. Thesis, Chromium(III) and the Glucose Tolerance Factor, University of Sydney, Australia, 1989. 

Chromium is considered to be a cofactor for insulin activity and part of an organic glucose tolerance factor. In common carp (Cyprinus carpio) fed low protein diets, the addition of chromium chloride salts in the diet (equivalent to 60.0 xg Cr+ /kg BW) or injected intraperitoneally (2.5 xg/kg BW), significantly decreased plasma glucose levels. Trivalent chromium supplementation in the diet improved glucose utilization in carp and tilapia when fed diets for 10 weeks containing 2.0 mg Cr/kg ration equivalent to 5% BW daily. Chromic oxide was more effective than chromium chloride, and both were more... 

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