Oral Chromium Picolinate Improves Insulin Resistance in Rat Model

BURLINGTON, Vt.--Obese rats that were administered oral chromium picolinate for three months exhibited improved insulin sensitivity and glucose disappearance as compared to control rats, according to researchers from the University of Vermont College of Medicine and Canadian colleagues from the University of Alberta in Edmonton who published their study in the June issue of the Journal of Nutrition (132, 6:1107-14, 2002) (www.nutrition.org). Because previous research suggested that chromium picolinate decreases insulin levels and improves glucose disposal in obese and diabetic populations, investigators sought to determine whether oral chromium picolinate supplementation would aid in the treatment of insulin resistance syndrome.

Male lean and obese hyperinsulinemic rats (rats with insulin resistance syndrome) were randomly assigned to either a control group or to a treatment group, receiving oral chromium picolinate (80 mcg/kg/d) in water. After three months, the obese rats in the treatment group had significantly lower fasting insulin levels and improved glucose disappearance compared with obese controls. In addition, the obese rats in the treatment group exhibited lower plasma total cholesterol and elevated high-density lipoprotein (HDL, "good") cholesterol levels compared to control.

Chromium picolinate supplementation was also seen to significantly enhance membrane-associated glucose transporter (Glut)-4 in obese rats after insulin stimulation, which relates to the body's ability to dispose of glucose properly. The Glut-4 transporter is required for moving glucose into cells where it can be burned. "These Glut-4 translocators have to go to the cell surface, and they basically make an opening in the surface of the cell to allow the glucose to go in to be metabolized," explained James Komorowski, director of technical affairs at Purchase, N.Y.-based Nutrition 21, the company that provided the active compound (as Chromax® chromium picolinate) for the study. While there was no difference in total skeletal muscle Glut-4 transporter among the groups, chromium picolinate supplementation was shown to enhance the activity of the Glut-4 transporter in the obese rats.

Researchers also noted that chromium picolinate supplementation did not alter plasma glucose or cholesterol levels in the lean rats. "That's a good thing in that if there's a healthy, normal animal, the administration doesn't lower blood sugar levels below normal," Komorowski said. "It was only effective in lowering elevated blood sugar levels in animals that had bad carbohydrate metabolism. But it didn't change levels in the normal animals, which you wouldn't want it to do."