Has Chromium Lost Its Luster??>

Has Chromium Lost Its Luster?

by Wellness Letter

Chromium is an essential trace min­eral for the human body, largely because of its vital role in processing and storing carbohydrates, fats, and protein. Notably, it helps cells respond properly to insulin—the hormone, produced in the pancreas, that makes blood sugar (glucose) available to the cells as our basic fuel.

Many foods supply small to moderate amounts of chromium—including whole grains, many vegetables (especially broccoli) and fruits, meat, egg yolks, nuts, peanuts, and dairy products—though the amounts are highly variable. Because of its important metabolic roles, chromium (especially chromium pico­linate) has become a popular supplement, and its marketers make many health claims.

Chromium’s mechanism of action in the body is poorly understood, and the amounts needed for optimal health are not clear. Thus, no Recommended Dietary Allow­ances (RDAs) for chromium have been set but rather only Adequate Intakes: 20 to 35 micrograms a day for adults (a microgram is one-thousandth of a milligram). Chromium deficiency is rare in the U.S. However, it’s difficult to diagnose people’s chromium sta­tus, since blood, urine, and hair levels do not reliably reflect the body’s stores and there is no reliable biochemical marker.

Dietary vitamin C and niacin increase chromium’s intestinal absorption. Sugary foods tend to be low in chromium, and high intakes of sugar can promote its excretion from the body.

Chromium supplements come in several forms, never as pure chromium. Besides chromium picolinate, there’s chromium chlo­ride, chromium nicotinate, and high-chro­mium yeast. Picolinate and nicotinate appear to be better absorbed than other forms. Most multivitamin/mineral pills contain anywhere from 20 to 180 micrograms of chromium. The effects of chromium supplementation may vary from person to person. Genetic and ethnic factors may play a role, along with degree of insulin resistance.

Chromium for diabetes?

Since chromium helps insulin do its job, and people with type 2 diabetes tend to have low blood levels of it, scientists have theorized that chromium supplements may help con­trol the disease—or help prevent it in people with prediabetes (insulin resistance). But just because low levels of chromium are associ­ated with diabetes, that doesn’t mean that low chromium causes the disease or that supplements will help.

Some studies have found that chromium picolinate (usually in doses of 200 micro­grams a day, sometimes as much as 1,000 micrograms) is beneficial for people with diabetes, while others have not. For instance, back in 1997, a widely publicized clinical trial in China found that chromium pico­linate helped control blood sugar in people with diabetes—but this may simply show the benefits of supplementation in a chro­mium-deficient population (chromium lev­els were not evaluated at the start of the study). Small clinical trials in the U.S. and Europe involving people with diabetes have so far produced no clear evidence of benefits from chromium supplements; thus, system­atic reviews and meta-analyses have reached conflicting conclusions. For instance:

  • A meta-analysis of seven clinical trials of people with diabetes, in the Journal of Pharmacy & Pharmaceutical Sciences in 2013, found that while chromium supple­ments (usually picolinate) may lower fasting blood sugar, they do not reduce HbA1c, a measure of long-term blood sugar control.
  • A systematic review of 20 clinical trials of people with diabetes, in Nutrition Reviews in 2016, found that most of them showed that chromium supplementation did not produce clinically significant improve­ments in blood sugar control or HbA1c.
  • In contrast, a pooled analysis of 28 clinical trials, in Molecular Nutrition and Food in 2018, found that chromium picolinate or chromium chloride did improve blood sugar control and HbA1c in people with diabetes.

Other chromium research

Heart disease. Studies on the effect of chromium supplements on blood choles­terol and triglyceride levels have also had inconsistent results. It’s possible that in chromium-deficient people, the supple­ments might reduce elevated LDL (“bad”) cholesterol somewhat, but even that is a big “might.” And there are better ways to accomplish this, including diet, exercise, and, if necessary, statin drugs.

Weight loss. Chromium may have a role in weight control and reducing body fat while preserving muscle, but so far the best-designed studies have failed to find a benefit. A 2013 systemic review and meta-analysis in Obesity Reviews, which included 20 trials lasting 8 to 26 weeks, found that chromium supplements resulted in an average weight loss of one pound, which is not clinically significant. And in a Brazilian study in the Journal of Trace Elements in Medicine and Biology in 2016, supplementation with chro­mium nicotinate did not lead to changes in body composition, significant weight loss, or improvement in glucose control in over­weight people with diabetes.

Exercise. Chromium picolinate is pro­moted for building muscle and improving athletic performance, but most studies have yielded disappointing results. A 2013 research review in the Journal of the Interna­tional Society of Sports Nutrition concluded that chromium is apparently ineffective as a performance aid.

A safety note on chromium

Few adverse effects of even high doses of chromium are known, so no upper limit has been established. Still, there are no data on long-term use of high doses, and there have been some case reports of acute kidney failure and liver damage in people taking them. Combining chro­mium with diabetes medication may cause blood sugar to dip too low.

While some early lab studies sug­gested that chromium picolinate could damage genetic material in animal cells and thus might increase the risk of cancer, subsequent research and reviews by regu­latory agencies have found that it is not genotoxic or carcinogenic. Note: The form of chromium used by the body is called trivalent chromium. Another form, called hexavalent chromium, usually produced by industrial processes, is a known carcin­ogen and toxin that can be inhaled (as in factories or from cigarette smoke) or ingested (as in contaminated water).

Bottom line

The best and safest way to consume chromium is from food. We don’t recommend chromium supplements because studies on them have mostly been small and short term and have yielded con­flicting results, so it’s not known if the sup­plements are beneficial in any way. If you have diabetes and do take supplemental chromium, talk to your doctor about it, since it may affect your blood sugar control.

This article first appeared in the UC Berkeley Wellness Letter.

Also see What’s Special About (Vitamin) K.