It is estimated that 90% of American diets are deficient in chromium, and the general population is thought to show signs of a marginal deficiencies, such as impaired glucose tolerance. Typical food sources of chromium include brewer’s yeast, whole grain cereals, broccoli, prunes, mushrooms and beer. However, the typical American diet is thought to exacerbate the problem of deficiency by the large-scale consumption of simple sugars in processed foods that may block chromium absorption. Brewer’s yeast, also called nutritional yeast, is thought to be the most bioavailable form of chromium, as it part of a bioactive complex called glucose tolerance factor (GTF) (Sterns et al., 1995).
Chromium is one of the essential trace minerals, and is important for carbohydrate metabolism and the potentiation of insulin. As chromium is well known for its difficulty in absorption, with only about 3% of the chromium we intake being absorbed, supplementation is a viable option. However, there are many types of chromium supplements on the market, and there have been recent concerns over the potential for toxicity of chromium picolinate, one of the most studied supplemental forms of chromium. These concerns have not been validated. Chromium chloride as well as some other forms of chromium (III) supplements do not have this concern (Vincent, 2000; Vincent 2003).
Although evidence is still mounting for the use of chromium to normalize blood sugar and meet marginal deficiencies, there seems to be a great potential as a supplement as the American population is sorely in need of nutritional answers to its large and growing overweight and diabetic populations.
Chromium’s clinical results so far for enhancing exercise performance have been limited. In a double-blind clinical study on the effects of chromium picolinate supplementation on football players, 200 mcg daily was administered. The outcome measurements were urinary excretion, girth and skinfold measures, percent body fat, lean body mass, and isometric and dynamic strength. No changes in any of the parameters were found, except for an increase in urinary chromium output (Clancy et al., 1994).
In two earlier studies, 200 mcg daily of chromium supplementation failed to show results. One study involved college students during weight training, and the only group that showed a significant difference were the females, who had a significant increase in body weight (Hasten et al., 1992). In another double-blind placebo controlled study, no enhancement on athletic performance was found (Walker et al., 2000).
Mixed results have been found clinically for chromium picolinate in weight loss. Pittler et al. (2003) performed a meta-analysis of chromium as it had been administered in randomized, double-blind, placebo controlled studies that reported on chromium picolinate’s use in weight loss. Ten studies matched the criteria of the meta-analysis, and the authors found a small benefit for the use of chromium picolinate in weight loss.
Volpe et al. (2001) tested the effects of chromium picolinate supplementation on body composition, resting metabolic rate, and zinc status in moderately obese women who underwent a prescribed exercise program. No changes in any of the measured outcomes were found except for a reduction in serum total cholesterol levels and total iron building capacity in both groups due to the increase in exercise for both groups.
In a clinical study on the effects of chromium picolinate supplementation on the risk factors for coronary artery disease and type II diabetes in obese women, 400 mcg daily was administered. In the groups that underwent exercise, chromium supplementation resulted in significant weight loss, whereas, the groups that did not undergo exercise but used chromium has significant weight gain. Chromium supplementation was only recommended then by the authors for obese women who were undergoing an exercise program (Grant et al., 1997).
In an earlier double-blind, placebo controlled study, chromium picolinate (400 mcg daily) supplementation was administered and investigated for its effect on body composition in obese people undergoing and exercise program. The results of this study showed no difference between the placebo and chromium groups (Trent et al., 1995).
Blood Sugar Control/ Diabetes & Chromium Ions
Ryan et al. (2003) performed a review of chromium (III) supplements for diabetes type II and hyperlipidemia. It was found that chromium reduced blood glucose in hyperglycemia, but not in people with normal blood glucose levels. Chromium was found to have variable effects on lipid levels.
In another recent study, Keszthelyi et al. (2003) found chromium supplementation used in diabetics for 6 months resulted in significant reductions in cholesterin levels, as well as a slight reduction in the HbA1c level.
Anderson et al. (2001) studied the effect of combined and individual zinc and chromium supplementation on oxidative stress and glucose homeostasis in people with type II diabetes. Diabetic subjects were supplemented with 30 mg/day of zinc (as zinc gluconate), or 400 micrograms/day of chromium (as chromium picolinate), or the combination, or placebo. The authors concluded that there are potential beneficial antioxidant effects of taking either the individual or combined supplementation of zinc or chromium in type II diabetics.
Bahijri (2000) found an improved lipid profile and glycemic control in a study on healthy adults given chromium tetrachloride daily. In this double-blind study, 200 micrograms or placebo was given daily for 8 weeks.
In a general study of urine and serum concentrations in diabetic and normal subjects, Ding et al. (1998) found that chromium loss is associated with aging and also diabetes occurrence.
Chromium supplementation on diabetic patients (with type I and type II diabetes) was investigated. Chromium supplementation (200 mcg daily) produced beneficial results in reducing insulin sulfonylurea or metformin requirements. Greater results were found for type II diabetics, but type I diabetics also showed good results with supplementation (Ravina and Slezack, 1993).
Safety / Dosage
The RDI for chromium is 120 mcg. There have been many concerns about the toxicity of chromium picolinate, however several recent studies have confirmed its safety (Campbell et al, 2004; Rhodes et al., 2005).
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EDITOR'S NOTE: This monograph can be found in The Health Professional's Guide to Dietary Supplements (Lippincott, Williams & Wilkins) by Shawn M. Talbott, PhD and Kerry Hughes, MS.