Alterations of chromium metabolism and effect of chromium supplementation in Turner's syndrome patients

A Comparative Study of Chromium: Therapeutic Uses and Toxicological Effects on Human Health

Chromium is an essential trace element whose deficiency can cause impairment of glucose tolerance, growth and various biological functions. There are two isotopes of chromium-trivalent chromium and hexavalent chromium. Both the isotopes of chromium have quite different effects on the human body. The objective of this narrative review is to compile the different effects of the two isotopes of chromium and give a comprehensive analysis of the effects of hexavalent and trivalent chromium. Data from various studies across different forums were compared to provide a concrete analysis of the therapeutic and harmful effects of two isotopes of chromium on human health. Chromium plays a vital role in the biological functions of the body. It might be helpful in balancing the glycaemic levels, triglyceride levels and cholesterol levels in the body. Excessive intake of chromium is harmful for health. Overexposure to chromium can lead to carcinogenic effects. Consumption of an insufficient amount of chromium might not be adequate as well. Trivalent chromium can be quite beneficial if taken in proper quantities. Hexavalent chromium can cause cancer. Trivalent chromium is beneficial, while hexavalent chromium is harmful to human health.

Beneficial effect of chromium supplementation on glucose, HbA1C and lipid variables in individuals with newly onset type-2 diabetes

PROJECT

Chromium is an essential nutrient involved in normal carbohydrate and lipid metabolism. It influences glucose metabolism by potentiating the action as taking part in insulin signal amplification mechanism. A placebo-controlled single blind, prospective study was carried out to investigate the effect of chromium supplementation on blood glucose, HbA(1)C and lipid profile in newly onset patients with type-2 diabetes.

PROCEDURE

Total 40 newly onset type-2 diabetics were selected and after 1 month stabilization further randomly divided into two groups viz. study group and placebo group. The study group received 9 g brewer's yeast (42 μg Cr) daily and the other placebo group received yeast devoid of chromium for 3 months. Subjects were instructed not to change their normal eating and living habits. Fasting blood glucose, HbA(1)C and lipid profile were analyzed at beginning and completion of the study.

RESULTS

Results revealed that fasting blood glucose level significantly reduced in the subjects consuming yeast supplemented with chromium (197.65±6.68 to 103.68±6.64 mg/dL; p<0.001). HbA(1)C values improved significantly from 9.51±0.26% to 6.86±0.28%; p<0.001 indicating better glycaemic control. In experimental group total cholesterol, TG and LDL levels were also significantly reduced from 199.66±3.11 to 189.26±3.01 mg/dL; p<0.02, 144.94±8.31 to 126.01±8.26; p<0.05 and 119.19±1.71 to 99.58±1.10; p<0.001 respectively.

CONCLUSIONS

These data demonstrate beneficial effect of chromium supplementation on glycaemic control and lipid variables in subjects with newly onset type-2 diabetes.

Evidence for synergism between chromium and nicotinic acid in the control of glucose tolerance in elderly humans

Impaired glucose tolerance results from Cr restriction in animals, and Cr supplementation improves glucose tolerance in diabetic animals. These effects are presumably due to the role of Cr in glucose tolerance factor (GTF), a complex of Cr and nicotinic acid believed to facilitate insulin binding. Humans, however, do not uniformly respond to Cr supplementation. The present study was designed to evaluate the possibility that the failure results from inadequate levels of dietary nicotinic acid to serve as substrate for GTF synthesis. Sixteen healthy elderly volunteers were divided into three groups and given either 200 micrograms Cr, 100 mg nicotinic acid, or 200 micrograms Cr + 100 mg nicotinic acid daily for 28 days and evaluated on days 0 and 28. Fasting glucose and glucose tolerance were unaffected by either chromium or nicotinic acid alone. In contrast, the combined chromium-nicotinic acid supplement caused a 15% decrease in a glucose area integrated total (p less than .025) and a 7% decrease in fasting glucose. None of the treatments exerted any effect on fasting or one-hour insulin levels. Thus, these data suggest that the inability to respond to chromium supplementation may result from suboptimal levels of dietary nicotinic acid.

Accuracy of biological trace-element determinations

Mounting evidence suggests that the accuracy of much of the published information on trace-element concentrations in biological matrices leaves much to be desired. Potential sources of error are: (a) inadequate sample collection and preparation (sampling errors); and (b) inaccuracies at the moment of the measurement (measurement errors). Probably much of what has been maintained on trace elements in human health and disease in the past will have to be revised in the future.

Trace elements in human body fluids and tissues

Published figures for trace element concentrations in body fluids and tissues of apparently healthy subjects are widely divergent. For a considerable time, the apparent disparities were readily ascribed to biological sources of variation such as age, sex, dietary habits, physiological conditions, environmental exposure, geographical circumstances, or similar influences. Growing evidence, however, suggests that this interpretation may be seriously questioned in numerous instances. First, values obtained in reference materials leave no doubt that some previous studies must have been subject to gross analytical inaccuracies. Second, it has now been thoroughly documented that inadequate sample collection and manipulation may drastically distort the intrinsic trace element content of biological matrices. This review scrutinizes data reported by a number of investigators. In an effort to settle the currently flourishing confusion, critically selected reference values are set forth for trace element levels in human blood plasma or serum, packed blood cells, urine, lung, liver, kidney, and skeletal muscle tissue.