Can Chromium Supplements Help Control Diabetes?

By Dace Trence, MD, FACE

Have you been tempted to try chromium supplements to help control your diabetes? If so, you’re not alone. Many people with type 2 diabetes (which results from insulin not working as it should, added to by decreasing insulin production over time) have increased chromium supplement use in recent years. In 2002, sales of chromium supplements were estimated at $85 million; more recent estimates place this number closer to $100 million.

An essential trace element, chromium is needed by the body in minute concentrations to help process carbohydrates, protein and fat and has long been thought to improve the action of insulin: In clinical research conducted in 1957, brewer’s yeast was found to prevent an age-related decline in the ability of rats to maintain normal levels of sugar in their blood and chromium was identified as the active ingredient in brewer’s yeast. Since that discovery, a number of researchers have examined the effects of chromium supplements for type 2 diabetes and other ailments.

There is also considerable interest in whether supplemental chromium may help treat the pre-diabetes state. However, the research thus far is inconclusive. No large, randomized, controlled clinical trials testing this have been reported in the U.S., although a recent report this year from France suggested a possible positive effect.

The French researchers presented a meta-analysis of data (an examination of multiple previously published reports) looking at 875 total participants ranging in age from 30 to 83 years old, with eight to 24 weeks of follow-up. Four different doses of supplemental chromium preparations were tested in these studies.

Compared to preparations without chromium, preparations containing the supplement showed no effect in participants’ HbA1C (a blood test that reports an average level of blood sugar over the previous three months). However, brewer’s yeast formulation of chromium did show a decrease in fasting blood sugar of about 20 milligrams per deciliter (mg/dL) in the study, which is a significant reduction. Whether this effect can be seen over the long term or whether it is significant to diabetes or pre-diabetes remains unclear, as the longest study lasted only six months.

Another landmark study in China using very large doses of chromium (between 600 to 1,000 micrograms per day) appeared to make a substantial reduction in blood sugar control in study participants with diabetes. However, the problem with this particular study is that the study participants had a significant chromium deficiency at the beginning of the research period.

Other research on chromium has studied its possible effects on lowering blood cholesterol levels, aiding weight loss and promoting more muscle or lean body mass. For example, in some studies, chromium has decreased total and low-density lipoprotein (LDL or “bad”) cholesterol, as well as lowering levels of triglyceride (a type of blood fat). Additionally, increased levels of apolipoprotein A, a component of high-density-lipoprotein cholesterol known as HDL or the “good” cholesterol have been detected in those with atherosclerosis who have taken chromium.

Yet other studies have shown that people who were on beta-blockers, a class of medication used for blood pressure control as well to protect heart function when coronary vessel disease is present, raised their good cholesterol levels when taking chromium. But other similar studies have not showed the same benefit.

Some researchers think that chromium supplements benefit only people with poor nutrition or low chromium levels, suggesting that the problem in the research might be a failure to measure chromium levels at the beginning of these studies. Other researchers have said that diet changes could have made a difference in study results and that diet diaries could be beneficial. Unfortunately, these types of studies haven’t been conducted.

Then there’s the theory about chromium and weight loss: Does chromium help people shed pounds? Another meta-analysis suggests not. No firm evidence could be determined comparing different doses of chromium with placebo for weight loss, percentage of body fat composition, or change in waist circumference. Additionally, significant side effects were noted in this particular study, leading to some study participants dropping out of the studies.

And although chromium has been popular with body builders, and is frequently a component of sports nutrition supplements, little data supports that chromium can help gain strength or build muscle mass.

According to guidelines from the National Institute of Health Office of Dietary Supplements, an adequate daily chromium intake for men is 35 micrograms per day and 25 micrograms per day for women. Even with these modest requirements, an estimated 90 percent of American diets are low in chromium. Adult U.S. women on average take in about 23 to 29 micrograms of chromium per day from food, while adult men average 39 to 54 micrograms per day. The amount of chromium delivered by dietary intake depends on the amount the body absorbs, which can differ from person to person, as well as what is eaten with the chromium-containing food. Overall absorption of chromium from the gut is low, ranging from less than 0.4 percent to 2.5 percent of the amount entering the gut. However, chromium absorption can be increased by eating foods that are high in vitamin C along with the chromium-containing foods, such as fruits and vegetables and their juices, and when the B vitamin niacin is also high (such as in meats, poultry, fish and grain products).

Chromium can be found in a number of readily available foods including whole-grain products, broccoli, mushrooms and green beans, but most foods contain only small amounts (less than two micrograms per serving). Meat and some fruits, vegetables and spices, are reliably good sources as well, while foods high in sugars such as table sugar and fructose are low in chromium.

There are risk factors for a chromium deficiency. Diets high in simple sugars (defined as when sugars account for more than 35 percent of ingested calories) can increase chromium excretion through the urine. Infection, acute exercise, pregnancy and lactation, and stressful incidents (such as physical trauma) also increase chromium losses. And age by itself could result in a relative chromium deficiency, although this suggestion is controversial.

Side effects from ingesting too much chromium are mild and commonly include itching, skin flushing and stomach irritation. But fast, irregular heartbeats, liver abnormalities, even kidney damage have been reported with chromium intake. If you have liver or kidney problems, or anemia, do not take chromium without first talking to your physician and healthcare team.

If you already take chromium, don’t exceed doses of 400–800 micrograms (mcg) per day, and make sure you’re checking your blood glucose levels regularly. Because it can interact with some medicines, including beta-blockers, insulin, nicotinic acid (niacin), corticosteroids, ibuprofen and aspirin, it’s important to let your physician know if you do take chromium—or any other supplement for that matter. And report any possible side effects to your doctor.

Now that you’re armed with all of this information, should you consider taking a chromium supplement to see if it helps with your blood sugar control? It’s an intriguing question, but more evidence is needed to prove the substance’s beneficial effects.

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Dr. Dace Trence is Director of the Diabetes Care Center and Professor of Medicine at the University of Washington Medical Center in Seattle. She is also the University of Washington Endocrine Fellowship Program Director and Director of Endocrine Days, a medical education program for endocrinologists practicing in the Pacific Northwest. She is on the American College of Endocrinology Board of Trustees and chairs the CME Committee and is also chair of the AACE Publications Committee.