Cinnamon was so prized in the ancient world that it was considered fit as a gift for royalty or even the gods. It was considered to have medicinal properties and even to this day is thought to lower blood sugar and thus serve as a natural therapeutic for diabetes. In 2008 a group headed by Dr. William Baker at the University of Connecticut performed a meta-analysis of all known clinical trials involving cinnamon and diabetes and found, unfortunately, that there was no real effect. (Click here for the reference) If this is so, why are people still publishing papers in peer reviewed journals on cinnamon and diabetes?
The answer is that something in cinnamon does have an insulin-like effect and while it might not be powerful enough in its natural form to affect blood sugar levels sufficiently to rise above the clatter and noise of human clinical variability, a component of cinnamon may serve as a lead compound in a new class of therapeutics. If we could identify that component and understand its mechanism of action we might be able to provide that compound as a drug in a dose 100 or 1000 times more concentrated than would be found in cinnamon.
Examples of identification and extraction of natural compounds and using them as starting points for drug development are many. Consider the willow tree. Its bark was used by ancient healers for a variety of purposes and from that bark we ultimately purified aspirin. The yew tree has given us taxol, now an important chemotherapeutic compound. Red wine has given us resveritrol, another potential chemotherapeutic and antioxidant compound. I occasionally serve on our Cancer Center board to review grant applications and we received one application a few years ago proposing to study resveritrol. The author had translated each resveritrol dose into the equivalent of glasses of wine (to be administered to the mice). The average dose was something like 300 glasses worth. The thought of a mouse imbibing 300 glasses of wine was an amusing image but it also underscored the sheer impossibility of taking in that amount of the substance via drinking.. The proposal was quite good (as well as entertaining) and was funded.
At any rate, papers on cinnamon continue to be published. The most recent report is out of India. Dr. Anand and co-workers from the University of Delhi has examined a component of cinnamon called cinnamaldehyde. They found that, like the thiazolidinedione drug family (think Avandia), it increased the translocation of a glucose transporter in muscle to the cell surface. This allows glucose to leave the blood and enter muscle tissue – a major mechanism by which we all get our blood glucose stored. Furthermore, they found that it altered the expression and activity of enzymes involved in storing glucose as glycogen. Finally, they showed that if one creates diabetic rats using streptozocin (the drug destroys the beta cells of the pancreas and has been used extensively to create diabetes in this animal model), treatment with cinnamaldehyde improved blood glucose levels.
How does it work? They have not yet figured that out. We are left with an intriguing compound and we await with interest the next installment of the story. In the meantime, enjoy your cinnamon.