Featured Nutrient: Chromium

After its discovery in the 1950s, chromium languished in relative obscurity. Most people seemed to get plenty of this essential nutrient without giving it a second thought. Now suddenly chromium supplements—usually in a form called chromium picolinate—have become superstars of the dietary-supplement aisle, touted as an easy way to shed fat, build muscles, prevent diabetes and even lower heart disease risk. Is it just hype?

What it does:

Like most such claims, the extravagant promises made for chromium start with a kernel of scientific truth. Chromium is required by the body for the process that turns food into usable energy, helping insulin prime cells to take up glucose. In the 1970s, studies showed that patients given chromium-free intravenous feeding regimens developed abnormal glucose metabolism; once they were given the mineral, the problems vanished.

As Americans and people from other affluent countries began to put on excess pounds and become insulin resistant, however, researchers started to wonder if extra chromium might help give insulin a boost. If so, the mineral could lower the risk not only of diabetes but also heart disease—and might even help some people lose weight.

From the start, the evidence was shaky. Though some studies did show an improvement in glucose metabolism, insulin resistance and cholesterol levels when people took chromium, others turned up no benefit at all. So the National Institutes of Health decided to put chromium to the test. In a study conducted in Boston and in Sydney, Australia, 40 patients with impaired glucose were randomly assigned to one of two groups. Half took an 800-microgram (mcg) chromium pill every day; the others a placebo.

The results, published last year, significantly dimmed chromium's luster. "After three months, chromium didn't improve glucose tolerance, insulin sensitivity or cholesterol levels," says lead researcher Jenny Gunton, Ph.D. And, while the chromium-takers lost a few centimeters around their waists, so did people in the placebo group—belying claims that chromium offers any special help in dropping pounds.

Other findings have tarnished chromium's image as a muscle-building miracle pill. Recent experiments that used the most sensitive methods to measure body fat and lean mass have shown no benefits from popping chromium supplements.

How much you need:

These disappointing findings with supplements don't mean the body doesn't need chromium. Some researchers still believe that falling short may add to the problem of insulin resistance and perhaps diabetes and heart disease. The National Institutes of Health's normal daily recommended intake for adults is 50 to 200 mcg. But because even the same food source can vary widely in how much it contains—and reliable measures of chromium in foods are hard to come by—tallying up your intake can be tricky (see box).

Where to get it:

Best sources of chromium are whole-grain breads and cereals, meat, nuts, prunes, raisins, beer and wine. If those don't show up frequently on your menu, taking a multivitamin/mineral combination, not a chromium supplement, is a wise move. One-a-day multis typically contain 150 mcg—more than enough to give most people all they need to stay healthy.

Food sources of chromium (mcg):

Since there's no large database yet for the chromium content of foods, use these values as a general guide rather than gospel.

Brewer's yeast (1 oz.) = 31.4

Whole-grain bread (1 oz. slice) = 11.8

Broccoli (1/2 cup) = 11.0

Beer (12 oz.) = 9-100

Grape juice (8 oz.) = 7.5

Turkey ham (1 oz. slice) = 3.5

Beef (3 oz.) = 2.0