Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 3/7/2005
Publication Date: 4/16/2005
Citation: Anderson, R.A. 2005. Polyphenols from cinnamon increase insulin sensitivity: Functional and clinical aspects [abstract]. 2005. Dietary Antioxidants, Trace Elements, Vitamins and Polyphenols. 4:154. Interpretive Summary:
Technical Abstract: We evaluated the insulin potentiating activity of aqueous extracts of several herbs, spices and medicinal plants using a rat epididymal assay and found that cinnamon was the most active followed by witch hazel, tea, allspice, bay leaves, nutmeg , cloves, mushrooms and brewer's yeast. The insulin potentiating activity was due to polyphenols in most of the samples since binding of the polyphenols with polyvinylpyrrolidone led to loss of insulin potentiating activity in all except mushrooms and brewer's yeast. The active polyphenols from cinnamon increased insulin receptor kinase and inhibited insulin receptor phoshatase with an associated increase in the phosphorylation of the insulin receptor. Increased phosphorylation of the insulin receptors leads to improved insulin function and improved insulin sensitivity. Polyphenols from cinnamon increased glucose uptake, glycogen synthesis and glucose utilization during a glucose clamp study in rats. Hypertension was also decreased. Consumption of 1, 3 or 6 grams of cinnamon (Cinnamomon cassia) per day for 40 days by subjects with type 2 diabetes led to 18 ' 29 % decreases in serum glucose, 23-30% decreases in triglycerides, 7-27% decreases in LDL-cholesterol and 12-26% decreases in total cholesterol with no significant changes in HDL-cholesterol. There were no significant differences among the three levels of cinnamon. Following the consumption of cinnamon for 40 days, there was no cinnamon consumed for 20 days and effects due to cinnamon were returning to the pre-study values but benefits were still significant. The active polyphenols found in cinnamon that improve insulin sensitivity and function were shown to be A-type procyanidin polymers with a trimer of molecular weight 864 and a tetramer with a molecular weight of 1152. In summary, our studies demonstrate that polyphenol compounds from cinnamon improve insulin sensitivity leading to improved insulin functions in cell culture, rats and humans.