By Amy Campbell | November 20, 2006 12:01 pm
Who would have thought that a trace mineral could cause so much confusion? As a dietitian, I remember many of my patients asking me if they should take chromium supplements. It was always a gray area for me, based on the ever-changing research.
Chromium is called a trace mineral and is essential to the human body. It’s needed to help process carbohydrate, protein, and fat, and it enhances the action of insulin. Chromium is found primarily in two different forms: trivalent chromium, the kind found in food, and hexavalent chromium, a toxic form found in some chemical substances. Food sources of chromium include meat, chicken, eggs, liver, some fruits and vegetables, whole grains, and brewer’s yeast. However, the amount of chromium in food can vary depending on agricultural and manufacturing processes. According to the Institute of Medicine, a component of the National Academy of Sciences, adequate daily intakes of chromium for adult women and men range from 24–35 micrograms (mcg) per day, with men needing more than women.
The link between chromium and diabetes originated in the 1950s, when researchers were able to prevent diabetes in rats by feeding them brewer’s yeast. Chromium was deemed to be the magic ingredient and was thereafter called a “glucose tolerance factor,” or GTF for short. Since then, quite a bit of research has been done to study the effect of chromium on various health conditions, primarily in the areas of diabetes, lipid control (including cholesterol and triglyceride levels), and weight loss.
Back in 2004, interest was sparked when researchers reported a link between chromium picolinate supplements and improved insulin sensitivity and glucose tolerance in people with diabetes. But, after more scrutiny, the conclusion was that most of the previous chromium studies had been flawed and that more research was needed.
A more recent, 6-month study published in 2005 showed improved insulin sensitivity and glucose tolerance in people with Type 2 diabetes taking a sulfonylurea drug and 1,000 mcg of chromium (in the form of chromium picolinate) compared to a placebo group that didn’t take chromium. Those taking chromium also gained less weight than the placebo group. However, this study involved only 37 subjects. And another 6-month study, also published in 2005, looked at chromium doses of either 500 or 1,000 mcg in 46 obese subjects with poorly controlled Type 2 diabetes and found no effect on HbA1c levels (a measure of blood glucose control over time), weight, or lipid levels compared to placebo.
Fortunately, another, larger study is underway which will look at the effects of 1,000 mcg of chromium picolinate in lean and obese people with Type 2 diabetes. This four-year study is sponsored by the National Institutes of Health and will hopefully clear up some of the confusion.
In the meantime, should you take a chromium supplement on the off chance it might help control your blood glucose levels? That’s something to discuss with your health-care team. At this time, there’s no compelling evidence that chromium has any beneficial effects on HbA1c, body weight, or lipid levels. If you already take chromium, don’t exceed doses of 400–800 mcg per day, and make sure you’re checking your blood glucose levels regularly. Report any possible side effects to your doctor. It’s also important to let your doctor know if you do take chromium (or any kind of supplement), as it can interact with some medicines, including beta-blockers, insulin, nicotinic acid (niacin), corticosteroids, ibuprofen, and aspirin.
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