Minerals - Chromium

• Method of Action
• Recommended Dietary Allowances

• Properties and Uses
• Toxicity Levels
• Food Sources

Description

Chromium concentration in human plasma is so variable that a reliable average value is difficult to determine. However, it is estimated that an adult has less than six milligrams of chromium in his or her body, which tends to accumulate in hair, skin, muscle, and fat. Hair and urine analysis are currently used to estimate chromium levels in humans.

Chromium concentrations in most tissues decrease steadily with age. Frequently this results in glucose intolerance and an increased incidence of diabetes among older persons since chromium plays an important role as a cofactor of the glucose tolerance factor (GTF), which facilitates the action of insulin. Chromium also helps regulate serum cholesterol and triglyceride levels.

Method of Action

Chromium is a cofactor of the glucose tolerance factor (GTF), which facilitates the binding of insulin to cell membranes. It accomplishes this by bridging the gap between the insulin molecule and the membrane, thereby allowing easier uptake of glucose from the cells by insulin. Niacin is also postulated as a constituent of the GTF.

Chromium is a cofactor of trypsin, and is important in the regulation of various enzymatic activities. Aside from its effects on the metabolism of carbohydrates, chromium is postulated as a factor in lipid metabolism and has been found, in small quantities, to be associated with RNA.

Once absorbed, chromium excretion occurs primarily in urine. For this reason, urine chromium concentration is a good indicator of the body’s chromium status. Efficiency of absorption is 1 to 20 percent.

Properties and Uses

Chromium is effective in reducing glucose intolerance, suffered by many elderly persons. It has also been used to improve the glucose tolerance in some children with kwashiorkor.

Chromium is complexed in the glucose tolerance factor (GTF). The GTF has been linked to reductions in blood glucose, serum cholesterol, and serum triglycerides. For this reason, chromium supplements have been used in some cases to reduce the incidence of arteriosclerosis.

Toxicity Levels

There is no evidence that excess dietary intake of chromium is toxic, but subacute toxicity has resulted from large excesses of chromium in drinking water. In excess, gaseous chromium (an industrial toxin) can be toxic.

Recommended Dietary Allowances

The daily chromium intake has been estimated at 80 to 100 micrograms.

Food Sources