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Keeping tabs on chromium's benefits is a little like watching a tennismatch. The mineral seemed to be winning for a while, but new evidenceindicates that maybe chromium should hang up the racket.
In 2004, researchers reported growing evidence that higher doses ofchromium supplementation, in the form of chromium picolinate, may improveinsulin sensitivity and glucose metabolism in patients with glucoseintolerance anddiabetes.1 However,the investigators concluded that most chromium studies have significantlimitations and that more trials are needed to confirm chromium picolinate'sinsulin-sensitizing benefits.
At the American Diabetes Association's 2005 Scientific Sessions, one ofthese researchers, William T. Cefalu, MD, of the Pennington BiomedicalResearch Center in Baton Rouge, La., reported improvements in insulinsensitivity and glycated hemoglobin (A1C) in subjects with type 2 diabetesreceiving only sulfonylurea and either 1,000 µg/day chromium as chromiumpicolinate or placebo over 6months.2 Inaddition, although all 27 subjects on sulfonylurea therapy gained weight,those receiving chromium "gained significantly less weight than theplacebo-treated group," Cefalusays.
In August 2005, the Food and Drug Administration (FDA) cited Cefalu'searlier research3 asevidence for its authorization of a qualified health claim: "One smallstudy suggests that chromium picolinate may reduce the risk of insulinresistance and therefore possibly may reduce the risk of type 2 diabetes. FDAconcludes, however, that the existence of such a relationship between chromiumpicolinate and either insulin resistance or type 2 diabetes is highlyuncertain."4
Two recent studies suggest no benefit from chromium picolinate.
In a 6-month, double-blind assessment of the effects of 500 or 1,000µg/day chromium picolinate compared with placebo in 46 obese patients withpoorly controlled type 2 diabetes, researchers found "no effect onweight, blood pressure, A1C, or lipid profile compared withplacebo."5
Another study finds no benefit on glucose tolerance, insulin resistance, orlipids in 40 patients with impaired glucose tolerance receiving 800 µg/daychromium picolinate for 3 months compared with placebo, despite evidence ofincreased serum chromiumlevels.6
"We had an effect on the chromium level; it just didn't changeglucose tolerance," says Jenny E. Gunton, PhD, now at Garvan Instituteof Medical Research and Westmead Hospital in Sydney, Australia.
Different chromium formulations may account for some of the variability inthe findings, Cefalu says. Studies of shorter duration and involving subjectson medications to improve insulin sensitivity may limit the benefits ofchromium supplementation.
Hopefully, a 4-year study of 1,000 µg/day chromium picolinate in lean toobese individuals with type 2 diabetes, sponsored by the National Institutesof Health, should provide some answers. "We've collected a large numberof patients and controls," says Cefalu, a participating researcher. Heexpects data will be available within a year.
Meanwhile, a daily supplement of 400–800 µg chromium "seemsto be the dose that is safe and well tolerated" in studies showingpositive effect, Cefalu says.
Gunton says she does not advise that individuals who already are takingchromium supplements stop taking them. "People with type 2 diabetes aremore likely to be deficient in a number of things, and that may includechromium," she says. However, Gunton does not advise people withdiabetes to start such supplements without more evidence of benefit.
Chromium Facts
References
2. Martin J, Matthews DE, Wang Z, et al.: Effect of chromiumpicolinate on body composition, insulin sensitivity, and glycemic control insubjects with type 2 diabetes (Abstract). Diabetes 54 (Suppl. 1): A427, 2005.
3. Cefalu WT, Bell-Farrow AD, Stegner J, et al.: Effect of chromiumpicolinate on insulin sensitivity in vivo. J Trace Elem ExpMed 12:71–83, 1999.
4. Food and Drug Administration: Qualified health claims: Letter ofenforcement discretion—Chromium picolinate and insulin resistance.Docket No. 2004Q-0144. Available online athttp://www.cfsan.fda.gov/~dms/qhccr.html.Accessed March 29, 2006.
5. Kleefstra N, Houweling ST, Jansman FG, et al.: Chromium treatmenthas no effect in patients with poorly controlled, insulin-treated type 2diabetes in an obese western population: A randomized, double-blind,placebo-controlled trial. Diabetes Care 29: 521–525, 2006.
6. Gunton JE, Cheung NW, Hitchman R, et al.: Chromium supplementationdoes not improve glucose tolerance, insulin sensitivity, or lipid profile: Arandomized, placebo-controlled, double-blind trial of supplementation insubjects with impaired glucose tolerance. DiabetesCare 28:712–713, 2005.
1. MedlinePlus Medical Encyclopedia: Chromium in diet. Availableonline athttp://www.nlm.nih.gov/medlineplus/ency/article/002418.htm.Accessed March 29, 2006.
2. Institute of Medicine: Dietary Reference Intakes forVitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron,Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc.Washington, D.C., The National Academies Press, 2001.
3. National Institutes of Health, Office of Dietary Supplements:Dietary supplement fact sheet: Chromium. Available online athttp://ods.od.nih.gov/factsheets/Chromium_pf.asp.Accessed March 29, 2006.
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