Glucose tolerance chromium complexes

Chromium. The history of the investigations estabHshing the essentiaHty of chromium has been reviewed (136). An effect of brewer s yeast in preventing or curing impaired glucose tolerance in rats was revealed, and the active factor was identified as a Cr(III) organic complex, glucose tolerance... 

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 is involved, as an organic complex, the glucose tolerance factor, in the... 

Brewers, yeast powder or tablets—This special product has long been used to prevent or treat malnutrition by providing extra protein and the vitamin B complex. However, it Is also one of the richest sources of both chromium and selenium —minerals that are likely to be supplied inadequately by ordinary diets. Furthermore, the chromium is present in an organic form (glucose tolerance factor) which is much more beneficial to the body than the inorganic forms of the mineral. 

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