Chromium: What is it? Chromium is a mineral that humans require in trace amounts, although its mechanisms of action in the body and the amounts needed for optimal health are not well defined. It is found primarily in two forms: first is trivalent (chromium 3+), which is biologically active and found in food, and second is hexavalent (chromium 6+), a toxic form that results from industrial pollution. Here we focuses exclusively on trivalent (3+) chromium.
Chromium is known to enhance the action of insulin, a hormone critical to the metabolism and storage of carbohydrate, fat, and protein in the body. In 1957, a compound in brewers' yeast was found to prevent an age-related decline in the ability of rats to maintain normal levels of sugar (glucose) in their blood. Chromium was identified as the active ingredient in this so-called "glucose tolerance factor" in 1959.
Chromium also appears to be directly involved in carbohydrate, fat, and protein metabolism but more research is needed to determine the full range of its roles in the body.
What foods provide chromium?
Chromium is widely distributed in the food supply, but most foods provide only small amounts (less than 2 micrograms [mcg] per serving). Meat and whole-grain products, as well as some fruits, vegetables, and spices are relatively good sources. In contrast, foods high in simple sugars (like sucrose and fructose) are low in chromium.
In 1989, the National Academy of Sciences established an "estimated safe and adequate daily dietary intake" range for chromium. For adults and adolescents that range was 50 to 200 mcg. In 2001, DRIs for chromium were established. The research base was insufficient to establish Recommended Dietary Allowance (RDAs), so AIs were developed based on average intakes of chromium from food as found in several studies.
mcg = micrograms.
Adult women in the United States consume about 23 to 29 mcg of chromium per day from food, which meets their AIs unless they're pregnant or lactating. In contrast, adult men average 39 to 54 mcg per day, which exceeds their AIs. The average amount of chromium in the breast milk of healthy, well-nourished mothers is 0.24 mcg per quart, so infants exclusively fed breast milk obtain about 0.2 mcg (based on an estimated consumption of 0.82 quarts per day). Infant formula provides about 0.5 mcg of chromium per quart.
What affects chromium levels in the body?
Absorption of chromium from the intestinal tract is low, ranging from less than 0.4% to 2.5% of the amount consumed, and the remainder is excreted in the facies. Enhancing the mineral's absorption are vitamin C (found in fruits and vegetables and their juices) and the B vitamin niacin (found in meats, poultry, fish, and grain products). Absorbed chromium is stored in the liver, spleen, soft tissue, and bone.
The body's chromium content may be reduced under several conditions. Diets high in simple sugars (comprising more than 35% of calories) can increase chromium excretion in the urine. Infection, acute exercise, pregnancy and lactation, and stressful states (such as physical trauma) increase chromium losses and can lead to deficiency, especially if chromium intakes are already low.
When can a chromium deficiency occur?
Chromium was found to correct glucose intolerance and insulin resistance in deficient animals, two indicators that the body is failing to properly control blood-sugar levels and which are precursors of type-2 diabetes. However, reports of actual chromium deficiency in humans are rare. Three hospitalized patients who were fed intravenously showed signs of diabetes (including weight loss, neuropathy, and impaired glucose tolerance) until chromium were added to their feeding solution. The chromium, added at doses of 150 to 250 mcg /day for up to two weeks, corrected their diabetes symptoms. Chromium is now routinely added to intravenous solutions.
Who may need extra chromium?
There are reports of significant age-related decreases in the chromium concentrations of hair, sweat and blood, which might suggest that older people are more vulnerable to chromium depletion than younger adults. One cannot be sure, however, as chromium status is difficult to determine. That's because blood, urine, and hair levels do not necessarily reflect body stores. Furthermore, no chromium-specific enzyme or other biochemical marker has been found to reliably assess a person's chromium status.
There is considerable interest in the possibility that supplemental chromium may help to treat impaired glucose tolerance and type-2 diabetes, but the research to till date is inconclusive. No large, randomized, controlled clinical trials testing this hypothesis have been reported in the United States. Nevertheless, this is an active area of research.
Lecturer, Deptt. of Kriyasharir
Dayanand Ayurvedic College & Hospital,