Insulin potentiating factor and chromium content of selected foods and spices

An unidentified factor that potentiates the action of insulin in glucose metabolism was investigated in selected foods and spices. Chromium content of these foods and spices was also determined. Foods and spices were extracted with 0.1N NH4OH (1:20, w/v) and the supernatants assayed for insulin potentiation activity in the rat epididymal fat cell assay. Among the selected foods, tuna fish, peanut butter, and vanilla ice cream had some insulin potentiating activity. Among the spices, apple pie spice, cinnamon, cloves, bay leaves, and turmeric potentiated insulin activity more than three-fold. Chromium concentration of foods ranged from 1 to 145 ng/g, and spices ranged from 4 to 1818 ng/g. Insulin potentiating activity of foods and spices did not correlate with total chromium. Spices are generally used for flavor and taste in food preparations, but cinnamon, cloves, bay leaves, and turmeric may have an additional role in glucose metabolism.