Use as Part of Your Diet to Help Maintain a Healthy Blood Sugar Level
In Vitro and Animal Studies
Research has revealed that a number of herbs and spices have insulin-like activity.2 In a study published in 2000 by the U.S. Department of Agriculture (USDA), cinnamon demonstrated the greatest ability to stimulate cellular glucose metabolism among 49 botanicals tested.
In a 2001 study, researchers at the USDA's Human Nutrition Research Center showed that bioactive compounds in cinnamon trigger an insulin-like response in fat cells. These compounds stimulated glucose uptake into cells and increased glycogen (stored glucose) production via activation of the enzyme, glycogen synthase.
The bioactive compounds in cinnamon appear to potentiate insulin activity at the level of the cell receptor for insulin. It has been shown that insulin resistance involves downregulation of "insulin signaling" characterized by dephosphorylation of the receptor. Enzymes called "protein tyrosine kinases" (PTPases) are believed to decrease receptor phosphorylation, and increased PTPase activity has been observed in insulin resistant rats. Cinnamon compounds have demonstrated the in vitro ability to inhibit PTP-1 and increase autophosphorylation of the insulin receptor.
In a recent animal study, cinnamon (cassia) extract was administered to rats for three weeks. Following this, the rats were infused with insulin and glucose to assess their insulin response. Increased phosphorylation of the insulin receptor was observed in skeletal muscle of these rats, suggesting that cinnamon has the ability to potentiate insulin function by normalizing insulin signaling, leading to improved uptake of glucose into skeletal muscle.
Until recently, the precise molecular structure of the bioactive compounds in cinnamon had not been clearly defined. The USDA has now determined that the bioactive compounds in cinnamon are water-soluble procyanidin Type-A polymers of catechin and epicatechin. In a 2004 study, type-A polymers were isolated from cinnamon and characterized by nuclear magnetic resonance and mass spectroscopy. Type-A polymers were found to increase in vitro insulin activity by a factor of 20. Type-A polymers also exhibited antioxidant activity, as measured by inhibition of free radical production in platelets. These results suggest that, in addition to regulating glucose metabolism, cinnamon may help protect cell membranes by controlling the lipid peroxidation associated with disruptions in insulin function.
Human Clinical Trial
The effect of cinnamon on glucose and blood lipids levels on people with type 2 diabetes was tested in a recent randomized, placebo-controlled trial. A total of 60 subjects were divided into six groups administered 1, 3, or 6 grams of cinnamon daily, in 500 mg capsules, or equal numbers of placebo capsules. The cinnamon or placebo capsules were consumed for two periods of 20 days each. Serum glucose, triglyceride, cholesterol, LDL cholesterol and HDL cholesterol were measured after 20 days, 40 days and again at the end of a 20-day wash-out period, during which neither cinnamon nor placebo was consumed.
In all three cinnamon groups, statistically significant reductions in blood glucose levels occurred, with decreases ranging from 18 to 29 percent. Interestingly, glucose levels remained significantly lower after the 20-day wash-out period (60 days from the study start) only in the group that took the lowest cinnamon dose (1 gram daily). The placebo groups showed no significant changes.
Decreases in triglyceride levels ranging from 23 to 30% were observed in all three cinnamon groups after 40 days. When the study ended at 60 days, triglyceride levels remained lower than at the study start in the 1 and 3 gram cinnamon groups, but not in the group taking 6 grams daily. Cholesterol reductions also occurred with the three cinnamon doses, with decreases ranging from 13 to 25% that were maintained at the study end. For LDL, the 3 and 6 gram cinnamon groups showed significant reductions from 10 to 24%, while in the 1 gram cinnamon group, non-significant reductions occurred after 40 days; LDL levels continued to decrease, reaching statistical significance at 60 days. With respect to HDL, significant increases were seen only in the 3 gram cinnamon group after 20 days; non-significant changes occurred in the 1 and 6 gram groups after 40 days.
The overall results of this trial demonstrate that cinnamon exerts a beneficial effect on blood glucose and lipid levels in people with type 2 diabetes, at daily intakes of 1 gram, and that this low dose is equally efficacious as are the higher doses of 3 and 6 grams.
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