C. verum: C. aromaticum J. Graham; C. zeylanicum Blume; and others; C. cassia: C. aromaticum Nees; C. longifolium Lukman; and others Lauraceae C. verum: Ceylon cinnamon; true cinnamon; C. cassia: cassia bark; Chinese cassia Several other species of Cinnamomum are also commonly traded using the name ‘cinnamon’. C. verum: Cinnamomi cortex; Cinnamomi corticis aetheroleum (Cinnamon oil). C. cassia: Cinnamomi cassaie cortex; Cinnamomi cassiae aetheroleum (Cassia oil). Dried inner bark from shoots of C. verum or stripped trunk bark from C. cassia; bark oil (obtained by steam distillation from the cortex) The major constituent of both C. verum and C. cassia is cinnamaldehyde at 65–80% and 90% of the volatile oil, respectively. C. verum also contains o-methoxycinnamaldehyde. Its volatile oil contains 10% eugenol and terpenoids including linalool. In C. cassia, only a trace of eugenol is found, and C. cassia is also lacking in monoterpenoids and sesquiterpenoids. Coumarin is present in C. cassia, but not in C. verum (Barceloux 2009; Pharmaceutical Press Editorial Team 2013; WHO 1999). A number of the clinical and pre-clinical studies do not clearly distinguish between the various species of cinnamon, which may result in slightly conflicting data, since the species differ slightly in phytochemical composition. Overall, the evidence for blood-sugar-lowering effects is positive but conflicting. A Cochrane review identified 10 randomised controlled trials, involving 577 participants with diabetes mellitus, who were administered a mean daily dose of 2 g ‘cinnamon’ (predominantly C. cassia), for a period of 4–16 weeks. The effect on fasting blood glucose was inconclusive, and no significant difference between cinnamon and control groups was found in levels of glycosylated haemoglobin A1c (HbA1c), serum insulin or postprandial glucose (Leach and Kumar 2012). In contrast to the Cochrane findings, another systematic review and meta-analysis (of six randomised controlled trials lasting 40 days–4 months, n = 435) found that cinnamon (daily dose 1–6 g) exerted a beneficial effect on glycaemic control, both HbA1c and fasting plasma glucose (FPG) (Akilen et al. 2012). A recent systematic review of randomised controlled trials of ‘cinnamon’ (both C. cassia and C. verum) concluded that its consumption is associated with a statistically significant decrease in levels of fasting plasma glucose, total cholesterol, LDL-C, and triglyceride levels, and an increase in HDL-C levels; however, no significant effect on hemoglobin A1c was found. The authors suggested that the high degree of heterogeneity in the studies may limit their applicability to patient care, because the dose and duration of therapy were unclear (Allen et al. 2013). A meta-analysis of three randomised controlled clinical trials (from a possible 93 studies found), two of which involved individuals with type 2 diabetes and one with pre-diabetic syndrome, found that short-term administration of cinnamon was associated with a notable reduction in both systolic and diastolic blood pressure. However, the findings were based on a low number of patients, and further longer term randomised controlled trials involving a large number of patients are required (Akilen et al. 2013).
Cinnamon; Chinese Cinnamon/Cassia
Cinnamomum verum J. Presl; C. cassia (L.) J. Presl
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