Polyphenols in cinnamon mimic insulin.

USDA-ARS scientists and university colleagues have isolated and characterized several polyphenolic polymer compounds from cinnamon bark that could become natural ingredients in products intended to lower blood sugar levels. The investigators have named the newly identified chemical structures in a patent application.

Impaired sugar and fat metabolism is present in millions of people and may lead to type-2 diabetes and cardiovascular diseases. In test tube assays using fat cells, the polyphenolic polymers increased sugar metabolism 20-fold. As you know, insulin is a hormone made by the pancreas to regulate sugar metabolism. In people with type-2 diabetes, either the pancreas doesn't make enough insulin, or the body is unable to use it correctly. Both conditions lead to unhealthy blood levels of sugar that would otherwise provide energy to muscles.

During a decade of efforts to find natural compounds that could help maintain normal blood sugar levels, the scientists tested several components of cinnamon. The newly characterized chemical structures are closely related to a previously reported chemical derivative of cinnamon, MHCP (methylhydroxychalcone polymer). The researchers also tested scores of other plant extracts, but none displayed the insulin-enhancing activity approaching that of cinnamon.

The new compounds increase insulin sensitivity by activating key enzymes that stimulate insulin receptors, while inhibiting the enzymes that deactivate them. Insulin receptor kinase is activated, and insulin receptor phosphatase is inhibited, leading to maximal phosphorylation of the insulin receptor, which in turn leads to increased insulin sensitivity.

Polyphenols are known for their antioxidant, anticancer and anti-inflammatory functions, but they have not been known to improve insulin function. The polyphenolic polymers in cinnamon bark have antioxidant effects which may provide synergistic benefits to persons with various forms of diabetes.

Another recently published human research study from the scientists showed considerable improvements in glucose and fat metabolism in volunteers who followed a diet that included modest amounts of table cinnamon for 40 days. Table cinnamon is made from cinnamon bark and contains both water-soluble and fat-soluble compounds.

Fat-soluble compounds may accumulate in the body if ingested over a long period. At this time, there are no data on the potential effects of long-term ingestion of table cinnamon. But the newly defined chemical structures are isolated from water extracts of cinnamon and appear to be nontoxic in any quantity. Several studies are underway on the mechanisms and other factors that may improve the activity of the compounds. Human studies are underway as well.

Further information. Richard Anderson, USDA-ARS Nutrient Requirements and Functions Laboratory, 10300 Baltimore Ave., Building B307C, Room 224, Beltsville, MD 20705; phone: [phone]; fax [phone]; email: [e-mail].