18 VOLUME 20 NUMBER 1 • JUNE 2023 REVIEW SA JOURNAL OF DIABETES & VASCULAR DISEASE consumption have shown a decrease in pre- and postprandial glucose levels as well as a decrease in insulin resistance and glycated haemoglobin (HbA1c) levels. In animal studies, administering cinnamon to mice fed on high-fructose diets showed an improvement in glucose tolerance and the prevention of insulin resistance.3,4 Watersoluble cinnamon polyphenols administered to mice were found to develop adipogenesis.5 Cinnamon (C cassia) given to animals with type 2 diabetes for six weeks reduced blood glucose levels.6 Cinnamaldehyde from (C zeylanicum) administered for 45 days to diabetic Wistar mice showed that plasma glucose levels decreased significantly compared to the control group.7 Mice given cinnamon oil (25.5 mg/kg and 100 mg/kg) for 35 days showed a significant decrease in pre-prandial plasma glucose compared to the control group. Healing was observed in pancreatic beta-cells in this study.8 See Table 2 for the effect of different preparations of cinnamon in type 2 diabetes. Discussion The identification of a safe, durable, cost-effective adjunct to reduce the progression of prediabetes to diabetes is a clinically relevant goal. Cinnamon preparations such as cinnamon water extract were shown to have an effect on cell viability, glucose uptake and gene expression in HepG2 cells and these effects were comparable to metformin’s effect of increasing insulin sensitivity, inhibiting gluconeogenesis, increasing glucose uptake, and activating adenosine-activated protein kinase.20 This suggests that adding cinnamon to a dietary food matrix can serve as an effective supplement in mitigating type 2 diabetesrelated metabolic dysfunction. Cinnamon has pleotropic benefits that include anti-oxidative activity, and therapeutic and preventative properties against disease and disorders.2 Cinnamon has a high oxygen radical absorbance capacity (ORAC) score, which is a measurement of antioxidants in foods. Cinnamon has an ORAC value of 267 536/100 g and is packed with a variety of antioxidants that protect the body cells from free radical damage, inflammation and carcinogens. The United States Food and Drug Agency has issued a statement that cinnamon is generally recognised as safe (GRAS) for consumption.21 Cinnamon can be used in everyday foods with no side effects.22 A previous study also recommended cinnamon as an adjuvant to regular diabetes treatment.23 Conclusion There are some limitations to the current research on cinnamon due to its heterogeneity, and herbal preparations do not undergo strict manufacturing quality control compared to pharmaceutical products. Further rigorous and long-term research is mandated in order to substantiate the clinical effects with regard to preparation and dose of cinnamon. References 1. Barceloux DG. Medical Toxicology of Natural Substances: Foods, Fungi, Medicinal Herbs, Plants, and Venomous Animals, 2008: 39–43. 2. Suriyagoda L, Mohatti AJ, Janak K. Ceylon cinnamon: much more than just a spice. Plants People Planet 2021; 3(3): 319. 3. Kannappan S, Jayaram T, Rajasekar P, et al. Cinnamon bark extract improves glucose metabolism and lipid profile in fructose fed rats. Singapore Med J 2006; 47(10): 858–863. 4. Qin B, Nagaski M, Ren M, et al. Cinnamon extract prevents the insulin resistance induced by a high-fructose diet. Horm Metab Res 2004; 36(2): 119–125. 5. Taher M, Abdul Majid FA, Sarmidi MR. Cinnamtannin B1 activity on adipocytes formation. Med J Malaysia 2004; 59(1): 97–98. 6. Verspohl EJ, Bauer K, Nedderman E. Antidiabetic effect of Cinnamomum cassia and Cinnamomum zeylanicum in vivo and in vitro. Phytother Res 2005; 19(3): 203–206. 7. Subash Babu P, Prabuseenivasan S, Ignacimuthu S. Cinnamaldehyde – A potential antidiabetic agent. Phytomedicine 2007; 14(1): 15–22. 8. Ping H, Zhang G, Ren G. Antidiabetic effects of cinnamon oil in diabetic KK-Ay mice. Food Chem Toxicol 2010; 48(8–9): 2344–2349. 9. Ziegenfuss TN, Hofheins JE, Mendel RW, Landis J, Anderson RA. Effects of a water-soluble cinnamon extract on body composition and features of the Table 2. The effect of different preparations of cinnamon in type 2 diabetes Dose Duration Effect 500-mg cinnamon capsules Decreased pre- and postprandial glucose levels9,10 1 g, 3 g, 6 g 40 days Decreased blood glucose level11 1 g 90 days Decreased HbA1c level 12 2 g 12 weeks Decreased HbA1c level 13 6 g 4 weeks Decreased blood glucose level14 1.5 g 6 weeks No change15 10-g capsules 12 weeks No change16 3 g ground cinnamon 90 days Decreased HbA1c and fasting glucose levels17 1.2 g/day to 6 g/day 4 to 18 weeks Decreased aqueous cinnamon or raw powder fasting glucose, TC, LDL-C and triglyceride levels, increased HDL-C level18 500-mg capsules tds 12 weeks Improved fasting glucose level and glucose tolerance in prediabetics19 HbA1c, glycated haemoglobin; TC, total cholesterol; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol. Table 1. The different types of cinnamon species found in Asia and Australia2 Cinnamomum Country C zeylanicum Blume, (Ceylon cinnamon Sri Lanka or true cinnamon), C verum C cassia (Cassia cinnamon) C aromatica, China C camphora C loureiroi Vietnam C sintoh Java and Sumatra C ineris Japan and South India C burmanii Indonesia C culilawan Maluca Island, Indonesia C rubrum Ambon Island, Indonesia C glaucasceus Nepal C tamala India and Nepal C obtuse formalin North East India and Myanmar C olivera Australia C citriodorum Malabar
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