Despite being an essential trace mineral, the precise mechanism of action of chromium is not well defined. Its primary function appears to be enhancing the action of insulin, which plays a role in carbohydrate, fat and protein metabolism and storage. Trivalent chromium is the predominant form in the body and the biologically active form found in food.
Roles in Health
Chromium enables the body to maintain normal blood sugar levels by enhancing the action of insulin and moving glucose from the blood into cells, which leads to greater insulin sensitivity.
Although chromium has been associated with many health benefits, evidence is lacking. Some studies show improved glucose metabolism and lipid levels with chromium supplementation in people with diabetes. National Health and Nutrition Examination Study data from 1999 to 2010 showed a lower incidence of Type 2 diabetes in those taking a chromium supplement. Other studies show conflicting results or no benefit.
Supplemental chromium, primarily in the form of chromium picolinate, has been studied for its potential impact on weight loss and improved insulin resistance. Although some studies have shown a modest reduction in body weight, the results are not clinically significant and side effects can be unpleasant.
Some body builders use chromium supplements because of the relationship between chromium and insulin, which is an anabolic hormone. However, most research shows chromium supplementation does not improve body composition.
While some studies have shown chromium supplementation can decrease total and LDL cholesterol in certain populations, the role of chromium supplements in lipid metabolism is inconclusive.
Ideal amounts of chromium are not well-defined. In 2001, the Food and Nutrition Board of the Institute of Medicine defined an Adequate Intake, or AI, level using estimates of average dietary consumption in specific populations. Daily AI begins at 0.2 micrograms for the first six months of life and progresses to 15 micrograms for ages 4 to 8. At age 9, daily AI begins at 21 micrograms for females and progresses to 25 micrograms up to age 50; for males, the daily AI begins at 25 micrograms and advances to 35 micrograms up to age 50. Pregnant and lactating women have a daily AI of 29 to 30 micrograms and 44 to 45 micrograms respectively. At age 50, daily AI is 20 micrograms for females and 30 micrograms for males.
A Tolerable Upper Intake Level has not been established because few adverse effects are associated with excess intake.
Sources of Chromium
Small amounts of chromium are found naturally in foods. Most people consuming a balanced diet get enough chromium from food and absorption can be enhanced with foods rich in vitamin C and niacin.
|? cup broccoli||11mcg||Excellent|
|1 cup grape juice||8mcg||Excellent|
|1 whole-wheat English muffin||4mcg||Good|
|1 cup mashed potatoes||3mcg*|
|3 ounces beef||2mcg*|
|1 cup orange juice||2mcg*|
|3 ounces turkey breast||2mcg*|
*Must have at least 3.5mcg chromium per serving to be?considered a good source.
Chromium picolinate can provide as much as 500 micrograms per dose. Chromium chloride, chromium nicotinate and high-chromium yeast are other supplement forms of trivalent chromium. Evidence for the use of chromium supplements is lacking and it is not clear which form is best.
Signs of Deficiency
Because there are no tools to accurately measure chromium status, identifying deficiencies is difficult. Theoretically, a deficiency could impair glucose tolerance and blood sugar control and may contribute to glucose intolerance or the development of Type 2 diabetes. People on long-term parenteral nutrition may have inadequate intake of chromium unless it is administered daily.
Toxicity of trivalent chromium is low because it is poorly absorbed and rapidly excreted in urine. Chromium supplements in large amounts can induce side effects such as stomach problems, watery stool, vertigo, headaches, hives, low blood sugar and kidney or liver damage.
Populations at Risk
Pregnant and lactating women, children and people with liver or kidney disease should not take chromium supplements without consulting a doctor. Chromium may impair absorption, enhance excretion or amplify the effect of thyroid medications, antacids, acid reflux drugs, corticosteroids, beta-blockers, insulin and some painkillers.
After years of research, the nutritional role of chromium continues to be debated. Since deficiency is rare and studies are inconclusive regarding potential benefits of supplements, chromium intake via food is recommended.