Some dieters say that chromium

• helps decrease body fat.
• helps improve muscle tone.

Chromium is mainly used to stabilize blood sugar. The major role for chromium in weight loss is to correct insulin resistance caused by chromium deficiency. However, assessing chromium deficiency is difficult since normal blood levels are of such a low concentration that they can escape detection by even the most sensitive instruments. Hair and toenail levels can be evaluated, but these tests are not routinely done.

Known causes of chromium deficiency include malnutrition, TPN (total parenteral nutrition), alcoholism, and strenuous exercise, which can cause what is called “chromium dumping.”

The mineral chromium plays an essential role in the metabolism of carbohydrates and fats and in the action of insulin. Chromium, usually in a form called chromium picolinate, has been studied for its potential role in altering body composition. Chromium has primarily been studied in body builders, with conflicting results.¹ In people trying to lose weight, a double-blind study found that 600 mcg per day of niacin-bound chromium helped some participants lose more fat and less muscle.²However, three other double-blind trials have found no effect of chromium picolinate on weight loss,^{3 , 4 , 5} though in one of these trials lean body mass that was lost during a weight-loss diet was restored by continuing to supplement chromium after the diet. A recent comprehensive review combining the results of ten published and unpublished double-blind studies concluded that chromium picolinate supplementation may have a small beneficial effect on weight loss.⁶

In supplemental amounts (typically 50–300 mcg per day), chromium has not been found to cause toxicity in humans. While there are a few reports of people developing medical problems while taking chromium, a cause-effect relationship was not proven. One study suggested that chromium in very high concentrations in a test tube could cause chromosomal mutations in ovarian cells of hamsters.^{7 , 8} Chromium picolinate can be altered by antioxidants or hydrogen peroxide in the body to a form that could itself create free radical damage.⁹ In theory, these changes could increase the risk of cancer, but so far, chromium intake has not been linked to increased incidence of cancer in humans.¹⁰

One report of severe illness (including liver and kidney damage) occurring in a person who was taking 1,000 mcg of chromium per day has been reported.¹¹ However, chromium supplementation was not proven to be the cause of these problems. Another source claimed that there have been reports of mild heart rhythm abnormalities with excessive chromium ingestion.¹² However, no published evidence supports this assertion.

Three single, unrelated cases of toxicity have been reported from use of chromium picolinate. A case of kidney failure appeared after taking 600 mcg per day for six weeks.¹³ A case of anemia, liver dysfunction, and other problems appeared after four to five months of 1,200–2,400 mcg per day.¹⁴ A case of a muscle disease known as rhabdomyolysis appeared in a body builder who took 1200 mcg over 48 hours.¹⁵ Whether these problems were caused by chromium picolinate or, if so, whether other forms of chromium might have the same effects at these high amounts remains unclear. No one should take more than 300 mcg per day of chromium without the supervision of a doctor.

Chromium supplementation may enhance the effects of drugs for diabetes (e.g., insulin, blood sugar-lowering agents) and possibly lead to hypoglycemia. Therefore, people with diabetes taking these medications should supplement with chromium only under the supervision of a doctor.

Preliminary research has found that vitamin C increases the absorption of chromium.¹⁶

The best source of chromium is true brewer’s yeast. Nutritional yeast and torula yeast do not contain significant amounts of chromium and are not suitable substitutes for brewer’s yeast. Chromium is also found in grains and cereals, though much of it is lost when these foods are refined. Some brands of beer contain significant amounts of chromium.