Herbs & Supplements:
Chromium
Supplement Forms / Alternate Names:
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Chromium Picolinate, Chromium Polynicotinate, Chromium Chloride, High-Chromium Brewer's Yeast
Principal Proposed Uses
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Diabetes, Insulin Resistance and Abnormal Glucose Tolerance, Weight Loss ("Fat Burning"), Heart Disease Prevention
Other Proposed Uses
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Performance Enhancement, High Cholesterol, Syndrome X, Functional Hypoglycemia, Acne, Migraine Headaches, Psoriasis
Chromium is a mineral the body needs in very small amounts, but it plays a significant role in human nutrition. Chromium's most important function in the body is to help regulate the amount of glucose (sugar) in the blood. Insulin plays a starring role in this fundamental biological process, by regulating the movement of glucose out of the blood and into cells. Scientists believe that insulin uses chromium as an assistant (technically, a cofactor) to "unlock the door" to the cell membrane, thus allowing glucose to enter the cell. In the past, it was believed that, to accomplish this, the body first converted chromium into a large chemical called glucose tolerance factor (GTF). Intact GTF was thought to be present in certain foods, such as Brewer’s yeast, and for that reason such products were described as superior sources of chromium. However, subsequent investigation indicated that researchers were actually creating GTF inadvertently during the process of chemical analysis. Scientists now believe that there is no such thing as GTF. Rather, the body uses a very small protein called low molecular weight chromium-binding substance (LMWCr) to facilitate the action of insulin. LMWCr does not permanently bind chromium, and is not a likely source of chromium in foods.83-85
Based on chromium's close relationship with insulin, this trace mineral has been studied as a treatment for diabetes. The results have been generally positive: it seems likely chromium supplements can improve blood sugar control in some people with diabetes. Chromium also might be helpful for more mild abnormalities in blood sugar metabolism. One study suggests that chromium might aid in weight loss, as well, but other studies failed to find this effect.
Requirements/Sources
The official U.S. recommendations for daily intake are as follows:
- Infants 0–6 months, 0.2 mcg
7–12 months, 5.5 mcg
- Children 1–3 years, 11 mcg
4–8 years, 15 mcg
- Males 9–13 years, 25 mcg
14–50 years, 35 mcg
50 years and older, 30 mcg
- Females 9–13 years, 21 mcg
14–18 years, 24 mcg
19–50 years, 25 mcg
50 years and older, 20 mcg
- Pregnant women, 30 mcg (29 mcg if 18 years or younger)
- Nursing women, 45 mcg (44 mcg if 18 years or younger)
Some evidence suggests that chromium deficiency may be relatively common.1,86 However, this has not been proven, and the matter is greatly complicated by the fact that we lack a good test to identify chromium deficiency.2
Severe chromium deficiency has only been seen in hospitalized individuals receiving nutrition intravenously. Symptoms include problems with blood sugar control that cannot be corrected by insulin alone.
Corticosteroid treatment may cause increased chromium loss in the urine.3 It is possible that this loss of chromium may contribute to corticosteroid-induced diabetes.
Chromium is found in drinking water, especially hard water, but concentrations vary widely. Many good sources of chromium, such as whole wheat, are depleted of this important mineral during processing. The most concentrated sources of chromium are brewer's yeast (not nutritional or torula yeast) and calf liver. Two ounces of brewer's yeast or 4 ounces of calf liver supply between 50 and 60 mcg of chromium. Other good sources of chromium are whole grains, beer, and cheese.
Calcium carbonate interferes with the absorption of chromium.4
Therapeutic Dosages
The dosage of chromium used in studies ranges from 200 to 1,000 mcg daily. However, there may be potential risks in the higher dosages of chromium (see Safety Issues).
Some products state that they contain “GTF chromium.” Some of these products are manufactured from brewer’s yeast, which was once thought to contain GTF. Others contain chromium as chromium nicotinate, which bears a faint resemblance to the proposed GTF molecule. However, since GTF is no longer believed to exist, this claim should be disregarded.
Therapeutic Uses
Chromium has principally been studied for its possible benefits in improving blood sugar control in people with diabetes. Reasonably good evidence suggests that people with adult-onset (type 2) diabetes may show some improvement when given appropriate dosages of chromium.5 One study suggests that chromium may also be useful for diabetes that occurs during pregnancy.6 In addition, nondiabetic individuals with mildly impaired blood sugar control might benefit from chromium supplementation.7–10 Chromium has been sold as a "fat burner" and is also said to help build muscle tissue. While most studies evaluating chromium's ability to promote weight loss have not found benefits, the largest study did find some evidence that chromium can enhance fat loss.11–21
Chromium might help prevent heart disease.22
Studies evaluating chromium as a performance enhancer or aid to bodybuilding have yielded almost entirely negative results.23–31,87
Studies on whether chromium can improve cholesterol levels have returned mixed results.32–40 However, one study suggests that chromium combined with grape seed extract might have a beneficial effect.41 In addition, among individuals taking beta-blockers, chromium may raise levels of HDL ("good") cholesterol.42
According to some authorities, impaired blood sugar control, high cholesterol, weight gain, and high blood pressure are all part of a bigger picture, called metabolic syndrome X. Since chromium may be helpful for the first three of these conditions, chromium deficiency has been proposed as the cause of syndrome X. However, this has not been proven, and the existence of syndrome X is itself controversial.
Chromium has also been proposed as a treatment for acne, migraine headaches, and psoriasis, but there is as yet no real evidence that it works.
What Is the Scientific Evidence for Chromium?
Diabetes
Moderately strong evidence supports the use of chromium for diabetes. In a recent double-blind placebo-controlled study, 180 people with type 2 diabetes were given placebo, 200 mcg of chromium picolinate daily, or a higher dosage of chromium picolinate—1,000 mcg daily. Individuals taking 1,000 mcg showed marked improvements in blood sugar levels. Lesser but still significant benefits were also seen in the 200-mcg group but not in the placebo group.43
A double-blind trial of 78 individuals with diabetes compared two forms of chromium (brewer's yeast and chromium chloride) against placebo.44 This rather complex crossover study consisted of four 8-week intervals of treatment in random order. The results in the 67 participants who completed the study showed that both forms of chromium significantly improved blood sugar control.
Similarly positive results were seen in another small study.46 However, there have also been negative results.47,48
One placebo-controlled study of 30 women with pregnancy-related diabetes found that supplementation with chromium (at a dosage of 4 or 8 mcg chromium picolinate for each kilogram of body weight) significantly improved blood sugar control.49
Chromium might also be helpful for treating diabetes caused by corticosteroid treatment.50,51
Improved Blood Sugar Control in People Without Diabetes
Many individuals develop impaired responsiveness to insulin (insulin resistance) and mildly abnormal blood sugar levels. Small double-blind trials have found that chromium supplementation may be helpful,52–55 although one study found no benefit.56 Another small double-blind trial found that chromium improved the body's response to insulin among overweight people at risk of developing diabetes.57 There is growing evidence that mildly impaired blood sugar control increases the risk of heart disease (see Heart Disease Prevention, following), suggesting that chromium supplementation might be useful.
Weight Loss ("Fat Burning")
The evidence is mixed on whether chromium is an effective aid in weight loss. The largest study did find benefit, but other studies did not.
In one study, 154 individuals were given either placebo or 200 or 400 mcg of chromium picolinate daily.58 Participants were not advised to follow any particular diet. Over a period of 72 days, individuals taking chromium experienced significantly greater weight loss than those not taking chromium: over 2-1/2 pounds versus about 1/4 pound. Interestingly, individuals taking chromium actually gained lean body mass, so the loss of fat was more dramatic: over 4 pounds versus less than 1/2 pound.
Another double-blind study by the same researcher, however, failed to demonstrate benefit. In this 3-month trial, 122 moderately overweight individuals attempting to lose weight were given either placebo or 400 mcg of chromium daily.59 No statistically significant differences were seen between groups. Researchers had to resort to fairly complicated statistical maneuvers in an attempt to show some benefit.
In another study, 44 overweight women were given either placebo or 400 mcg of chromium per day.60 All participants were placed on an exercise program. Over a period of 12 weeks, no differences were seen between the two groups in terms of body weight, waist circumference, or percentage body fat.
Generally negative results were seen in other small double-blind trials as well.61–66
When larger studies find positive results and smaller studies do not, it usually indicates that the treatment under study is at most weakly effective. This may be the case with chromium as a weight-loss treatment.
Heart Disease Prevention
Insulin resistance, as well as mildly elevated blood sugar levels, appears to increase risk of heart disease.67–74 Chromium supplementation might help by improving insulin responsiveness and normalizing blood sugar.
An observational trial found associations between higher chromium intake and reduced risk of heart attack.75
Safety Issues
Although the precise upper limit of safe chromium intake is not known, it is believed that chromium is safe when taken at a dosage of 50 to 200 mcg daily.88 Side effects appear to be rare.
However, chromium is a heavy metal and might conceivably build up and cause problems if taken to excess. There is one report of kidney, liver, and bone marrow damage in a person who took 1,200 to 2,400 mcg of chromium for several months; in another report, as little as 600 mcg for 6 weeks was enough to cause damage.77,78 Such problems appear to be quite rare, and it is possible that these individuals already had health problems that predisposed them to such a reaction. The risk of chromium toxicity is believed to be higher in individuals who already have liver or kidney disease.88
Nonetheless, based on these reports, it’s possible that the dosage of chromium found most effective for individuals with type 2 diabetes—1,000 mcg daily—might present some health risks. We advise seeking medical supervision before taking more than 200 mcg of chromium daily.
Also, keep in mind that if you have diabetes and chromium is effective, you may need to cut down your dosage of any medication you take for diabetes.79 Medical supervision is advised.
There are also several concerns about the picolinate form of chromium in particular.
Picolinate can alter levels of neurotransmitters.89 This has led to concern among some experts that chromium picolinate might be harmful for individuals with depression, bipolar disease, or schizophrenia.81 There has also been one report of a severe skin reaction caused by chromium picolinate.80
Finally, there are also concerns, still fairly theoretical and uncertain, that chromium picolinate could cause adverse effects on DNA.82,90,91
The maximum safe dosages of chromium for women who are pregnant or nursing, or individuals with severe liver or kidney disease have not been established.
Interactions You Should Know About
If you are taking
- Calcium carbonate supplements or antacids: You may need extra chromium. You should also separate your chromium supplement and your doses of these substances by at least 2 hours, because they may interfere with chromium's absorption.
- Corticosteroids: You may need extra chromium.
- Oral diabetes medicationsorinsulin: Seek medical supervision before taking chromium because you may need to reduce your dose of these medications.
- Beta-blockers: Chromium supplementation may improve levels of HDL ("good") cholesterol.
View References
Last reviewed April 2002 by Medical Review Board
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