Clinical and biochemical aspects of chromium deficiency.

The essentiality of chromium (Cr) in animal and human nutrition is now well accepted. In animals, Cr deficiency can cause a diabetic-like state, impaired growth, elevated blood lipids, increased aortic plaque formation, and decreased fertility and longevity. The ability of Cr to potentiate insulin sensitivity has considerable experimental support. In the human, Cr deficiency has been demonstrated unequivocally in only one clinical situation, patients on total parenteral nutrition without added Cr. In such patients, impaired glucose tolerance, hyperglycemia, relative insulin resistance, peripheral neuropathy, and a metabolic encephalopathy have been noted with reversal of the clinical phenomena by Cr repletion. Many studies have been performed to determine whether Cr deficiency may be important in other clinical conditions, namely, diabetes mellitus, pregnant and parous women, and the aged population. Available data indicate that Cr supplementation can improve glucose metabolism in glucose intolerant individuals and decrease the total/HDL cholesterol ratio regardless of the status of glucose tolerance. However, whether Cr supplementation has long-term health benefits is unknown. Further, despite many tantalizing observations, it is still unclear whether Cr deficiency, latent or overt, is common in any human situation other than generalized malnutrition and total parenteral nutrition without added Cr. Technical uncertainties in the analysis of Cr, Cr contamination of food by the use of stainless steel processing equipment and eating utensils, and the lack of a clinically feasible test for Cr deficiency continue to impede progress in Cr research. Nevertheless, there is considerably more clarity as to plasma and urine Cr levels, food and tissue Cr content, and metabolic pathways of Cr metabolism than existed a decade ago. It is expected that progress will accelerate, since critical questions can now be addressed regarding the role of Cr in human nutrition.