A team of naturopathic physicians and scientists decided to systematically review the scientific literature for evidence of safety, efficacy and pharmacological activity of common and cassia cinnamon.
Eight studies involving humans involving the therapeutic efficacy of common and cassia cinnamon were found. One pharmacological study on antioxidant activity and seven clinical studies on various medical conditions were reported in the scientific literature, including three studies involving type 2 diabetes, and one each addressing Helicobacter pylori infection, activation of the olfactory cortex of the brain, oral candidiasis (fungal infection) in HIV, and chronic salmonellosis (bacterial infection found in individuals with compromised immune systems).
Common and cassia cinnamon had been investigated in animal studies for their anti-diabetic properties. Cassia cinnamon, however, had been the subject of three clinical trials while common cinnamon remained unstudied in humans.
Based on strong scientific evidence from two of three randomized clinical trials reviewed, cassia cinnamon demonstrated a therapeutic effect in reducing fasting blood glucose by 10.3 percent; the third clinical trial did not observe this effect. Cassia cinnamon, however, did not have an effect at lowering glycosylated haemoglobin.
One randomized clinical trial reported that cassia cinnamon lowered total cholesterol, LDL cholesterol and triglycerides; the other two trials, however, did not observe this effect. There was scientific evidence that at least one species of cinnamon was not effective at eradicating H. pylori infection. Common cinnamon showed weak to very weak evidence of efficacy in treating oral candidiasis in HIV patients and chronic salmonellosis.
"The studies we reviewed offered mixed results with therapeutic efficacy being demonstrated in some research efforts and not in others. This literature review has given us a clear road map for further research regarding the healing effects of cinnamon, a spice that continues to have a reputation for providing flavour and medicinal treatments," said Dr. Jean-Jacques Dugoua, the lead researcher.