CRITICAL REVIEW / SYNTHE ` SE CRITIQUE From type 2 diabetes to antioxidant activity: a systematic review of the safety and efficacy of common and cassia cinnamon bark 1 Jean-Jacques Dugoua, Dugald Seely, Dan Perri, Kieran Cooley, Taryn Forelli, Edward Mills, and Gideon Koren Abstract: Common (Cinnamomum verum, C. zeylanicum) and cassia (C. aromaticum) cinnamon have a long history of use as spices and flavouring agents. A number of pharmacological and clinical effects have been observed with their use. The objective of this study was to systematically review the scientific literature for preclinical and clinical evidence of safety, efficacy, and pharmacological activity of common and cassia cinnamon. Using the principles of evidence-based practice, we searched 9 electronic databases and compiled data according to the grade of evidence found. One pharmaco- logical study on antioxidant activity and 7 clinical studies on various medical conditions were reported in the scientific literature including type 2 diabetes (3), Helicobacter pylori infection (1), activation of olfactory cortex of the brain (1), oral candidiasis in HIV (1), and chronic salmonellosis (1). Two of 3 randomized clinical trials on type 2 diabetes pro- vided strong scientific evidence that cassia cinnamon demonstrates a therapeutic effect in reducing fasting blood glucose by 10.3%–29%; the third clinical trial did not observe this effect. Cassia cinnamon, however, did not have an effect at lowering glycosylated hemoglobin (HbA1c). One randomized clinical trial reported that cassia cinnamon lowered total cholesterol, low-density lipoprotein cholesterol, and triglycerides; the other 2 trials, however, did not observe this effect. There was good scientific evidence that a species of cinnamon was not effective at eradicating H. pylori infection. Com- mon cinnamon showed weak to very weak evidence of efficacy in treating oral candidiasis in HIV patients and chronic salmonellosis. Key words: cinnamon, cassia, diabetes, antioxidant, Cinnamomum verum, Cinnamomum zeylanicum, Cinnamomum aroma- ticum, systematic review. Re ´sume ´: La cannelle de Ceylan (Cinnamomum verum, C. zeylanicum) et la cannelle de Chine (C. aromaticum) sont utili- se ´es depuis longtemps comme e ´pices et aromatisants. De plus, leur utilisation est associe ´e a ` de nombreux effets pharmaco- logiques et cliniques. Nous avons eu pour objectif de faire une revue syste ´matique de la litte ´rature scientifique concernant les preuves pre ´cliniques et cliniques de l’innocuite ´, de l’efficacite ´ et de l’activite ´ pharmacologique de la cannelle de Cey- lan et de Chine. Nous avons utilise ´ les principes de la me ´decine factuelle et effectue ´ une recherche dans 9 bases de don- ne ´es, puis compile ´ les donne ´es en fonction du niveau de preuve obtenu. La litte ´rature a re ´ve ´le ´ une e ´tude pharmacologique Received 30 November 2006. Published on the NRC Research Press Web site at cjpp.nrc.ca on 5 October 2007. J.-J. Dugoua. 2 Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, ON M5S 3M2, Canada; Motherisk Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Research and Clinical Epidemiology, Canadian College of Naturopathic Medicine, Toronto, ON M2K 1E2, Canada. D. Seely. Department of Research and Clinical Epidemiology, Canadian College of Naturopathic Medicine, Toronto, ON M2K 1E2, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada. D. Perri. Department of Clinical Pharmacology and Toxicology, University of Toronto, Toronto, ON M5G 1X8, Canada. K. Cooley. Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, ON M5S 3M2, Canada; Department of Research and Clinical Epidemiology, Canadian College of Naturopathic Medicine, Toronto, ON M2K 1E2, Canada. T. Forelli. Department of Medical Education, New Chapter, Inc., Brattleboro, VT 05301, USA. E. Mills. Department of Research and Clinical Epidemiology, Canadian College of Naturopathic Medicine, Toronto, ON M2K 1E2, Canada; Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON L8N 3Z5, Canada. G. Koren. Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, ON M5S 3M2, Canada; Motherisk Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Clinical Pharmacology and Toxicology, University of Toronto, Toronto, ON M5G 1X8, Canada. 1 This article is one of a selection of papers published in this special issue (part 1 of 2) on the Safety and Efficacy of Natural Health Products. 2 Corresponding author (e-mail: jeanjacques.dugoua@utoronto.ca). 837 Can. J. Physiol. Pharmacol. 85: 837–847 (2007) doi:10.1139/Y07-080 # 2007 NRC Canada