1. Alam Khan, MS, PHD, Mahpara Safdar, MS, Mohammad Muzaffar Ali Khan, MS, PHD, Khan Nawaz Khattak, MS and Richard A. Anderson, PHD
Cinnamon Improves Glucose and Lipids of People with Type 2 Diabetes
Quick Summary of Study: The results of this study demonstrate that intake of 1, 3, or 6 g of cinnamon per day reduces serum glucose, triglyceride, LDL cholesterol, and total cholesterol in people with type 2 diabetes and suggest that the inclusion of cinnamon in the diet of people with type 2 diabetes will reduce risk factors associated with diabetes and cardiovascular diseases.
"OBJECTIVEï¿½The objective of this study was to determine whether cinnamon improves blood glucose, triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol levels in people with type 2 diabetes.
RESEARCH DESIGN AND METHODSï¿½A total of 60 people with type 2 diabetes, 30 men and 30 women aged 52.2 ï¿½ 6.32 years, were divided randomly into six groups. Groups 1, 2, and 3 consumed 1, 3, or 6 g of cinnamon daily, respectively, and groups 4, 5, and 6 were given placebo capsules corresponding to the number of capsules consumed for the three levels of cinnamon. The cinnamon was consumed for 40 days followed by a 20-day washout period.
RESULTSï¿½After 40 days, all three levels of cinnamon reduced the mean fasting serum glucose (18ï¿½29%), triglyceride (23ï¿½30%), LDL cholesterol (7ï¿½27%), and total cholesterol (12ï¿½26%) levels; no significant changes were noted in the placebo groups. Changes in HDL cholesterol were not significant.
CONCLUSIONSï¿½The results of this study demonstrate that intake of 1, 3, or 6 g of cinnamon per day reduces serum glucose, triglyceride, LDL cholesterol, and total cholesterol in people with type 2 diabetes and suggest that the inclusion of cinnamon in the diet of people with type 2 diabetes will reduce risk factors associated with diabetes and cardiovascular diseases."
2. Javed I, Faisal I, Rahman Z, Khan MZ, Muhammad F, Aslam B, Ahmad M, Shahzadi A. Lipid lowering effect of Cinnamomum zeylanicum in hyperlipidaemic albino rabbits. Pak J Pharm Sci. 2012 Jan;25(1):141-7.
Quick Summary of Study: Based on these studies, it can safely be said that Cinnamomum zeylanicum bark powder methanol extract equivalent to 0.75g/kg bark powder and Simvastatin (0.6 mg/kg b. wt.) were equally effective in treating hyperlipidaemia.
"The purpose of the present study was to investigate the lipid lowering effect of Cinnamomum zeylanicum (Cinnamon) in hyperlipidaemic albino rabbits. For this purpose, forty eight albino rabbits were randomly divided into eight equal groups; untreated control on normal routine feed, untreated control on butter and cholesterol, treated control on synthetic cholesterol lowering drug simvastatin (Tablet survive (R) 20 mg), three treated groups on three respective doses of C. zeylanicum bark powder and two treated groups on water and methanol extracts of C. zeylanicum bark powder. Butter ad lib and cholesterol powder 500 mg/kg body weight were used to induce experimental hyperlipidaemia in all groups except untreated control group. The results suggested that C. zeylanicum bark powder at the rate of 0.50 g/kg, 0.75 g/kg and methanol extract equivalent to 0.75 g/kg powder produced respective percent reductions in total lipids by 45, 49 and 64; triglycerides by 38, 53 and 60; total cholesterol by 53, 64 and 69 and LDL-cholesterol by 50, 59 and 62. However, at these dosage levels HDL-cholesterol showed respective percent increase of 42, 48 and 53. Nonetheless, C. zeylanicum bark powder at the level of 0.25g/kg and C. zeylanicum extract in water could not significantly reduce lipid profile indicators. Based on these studies, it can safely be said that C. zeylanicum bark powder methanol extract equivalent to 0.75g/kg bark powder and simvastatin (0.6 mg/kg b. wt.) were equieffective in treating hyperlipidaemia."
3. Dugoua JJ, Seely D, Perri D, Cooley K, Forelli T, Mills E, Koren G.
From type 2 diabetes to antioxidant activity: a systematic review of the safety and efficacy of common and cassia cinnamon bark. Can J Physiol Pharmacol. 2007 Sep;85(9):837-47.
Quick Summary of Study: Clinical trials on type 2 diabetes provided strong scientific evidence that Cinnamomum cassia demonstrates a therapeutic effect in reducing fasting blood glucose by 10.3%-29%.
"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 pharmacological 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 provided 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. Common cinnamon showed weak to very weak evidence of efficacy in treating oral candidiasis in HIV patients and chronic salmonellosis."
4. Couturier K, Qin B, Batandier C, Awada M, Hininger-Favier I, Canini F, Leverve X, Roussel AM, Anderson RA. Cinnamon increases liver glycogen in an animal model of insulin resistance. Metabolism. 2011 Nov;60(11):1590-7. Epub 2011 May 6.
Quick Summary of Study: The data herein demonstrates that, in insulin-resistant rats, cinnamon improves insulin sensitivity and enhances liver glycogen via regulating insulin signaling and glycogen synthesis.
"The objective of this study was to determine the effects of cinnamon on glycogen synthesis, related gene expression, and protein levels in the muscle and liver using an animal model of insulin resistance, the high-fat/high-fructose (HF/HFr) diet-fed rat. Four groups of 22 male Wistar rats were fed for 12 weeks with (1) HF/HFr diet to induce insulin resistance, (2) HF/HFr diet containing 20 g cinnamon per kilogram of diet, (3) control diet, and (4) control diet containing 20 g cinnamon per kilogram of diet. In the liver, cinnamon added to the HF/HFr diet led to highly significant increases of liver glycogen. There were no significant changes in animals consuming the control diet plus cinnamon. In the liver, cinnamon also counteracted the decreases of the gene expressions due to the consumption of the HF/HFr diet for the insulin receptor, insulin receptor substrates 1 and 2, glucose transporters 1 and 2, and glycogen synthase 1. In muscle, the decreased expressions of these genes by the HF/HFr diet and glucose transporter 4 were also reversed by cinnamon. In addition, the overexpression of glycogen synthase 3Î² messenger RNA levels and protein observed in the muscle of HF/HFr fed rats was decreased in animals consuming cinnamon. These data demonstrate that, in insulin-resistant rats, cinnamon improves insulin sensitivity and enhances liver glycogen via regulating insulin signaling and glycogen synthesis. Changes due to cinnamon in control animals with normal insulin sensitivity were not significant."
5. Davis PA, Yokoyama W. Cinnamon intake lowers fasting blood glucose: meta-analysis. J Med Food. 2011 Sep;14(9):884-9. Epub 2011 Apr 11.
Quick Summary of Study: Cinnamon intake, either as whole cinnamon or as cinnamon extract, results in a statistically significant lowering of fasting blood glucose (FBG) in people with type 2 diabetes or prediabetes.
"Cinnamon, the dry bark and twig of Cinnamomum spp., is a rich botanical source of polyphenolics that has been used for centuries in Chinese medicine and has been shown to affect blood glucose and insulin signaling. Cinnamon's effects on blood glucose have been the subject of many clinical and animal studies; however, the issue of cinnamon intake's effect on fasting blood glucose (FBG) in people with type 2 diabetes and/or prediabetes still remains unclear. A meta-analysis of clinical studies of the effect of cinnamon intake on people with type 2 diabetes and/or prediabetes that included three new clinical trials along with five trials used in previous meta-analyses was done to assess cinnamon's effectiveness in lowering FBG. The eight clinical studies were identified using a literature search (Pub Med and Biosis through May 2010) of randomized, placebo-controlled trials reporting data on cinnamon and/or cinnamon extract and FBG. Comprehensive Meta-Analysis (Biostat Inc., Englewood, NJ, USA) was performed on the identified data for both cinnamon and cinnamon extract intake using a random-effects model that determined the standardized mean difference ([i.e., Change 1(control) - Change 2(cinnamon)] divided by the pooled SD of the post scores). Cinnamon intake, either as whole cinnamon or as cinnamon extract, results in a statistically significant lowering in FBG (-0.49ï¿½0.2 mmol/L; n=8, P=.025) and intake of cinnamon extract only also lowered FBG (-0.48 mmol/Lï¿½0.17; n=5, P=.008). Thus cinnamon extract and/or cinnamon improves FBG in people with type 2 diabetes or prediabetes."
6. Xiaoyan Sheng, Yuebo Zhang, Zhenwei Gong, Cheng Huang, and Ying Qin Zang. Improved Insulin Resistance and Lipid Metabolism by Cinnamon Extract through Activation of Peroxisome Proliferator-Activated Receptors PPAR Res. 2008; 2008: 581348. Published online 2008 December 11.
Quick Summary of Study: The data herein suggests that cinnamon in its water extract form can act as a dual activator of Peroxisome proliferator-activated receptors "Î³&Î±" and may be a promising drug alternative in managing obesity-related diabetes and hyperlipidemia.
"Peroxisome proliferator-activated receptors (PPARs) are transcriptional factors involved in the regulation of insulin resistance and adipogenesis. Cinnamon, a widely used spice in food preparation and traditional antidiabetic remedy, is found to activate PPARÎ³ and Î±, resulting in improved insulin resistance, reduced fasted glucose, free fatty acids, low-density lipoprotein cholesterol, and Aspartate aminotransferase levels in high-caloric diet-induced obesity (DIO) and db/db mice in its water extract form. In vitro studies demonstrate that cinnamon increases the expression of peroxisome proliferator-activated receptors Î³ and Î± (PPARÎ³/Î±) and their target genes such as Lipoprotein lipase, Fatty acid transporter "CD36", Glucose transporting protein 4, and Acyl-CoA oxidase in 3T3-L1 adipocyte. The transactivities of both full length and ligand-binding domain (LBD) of PPARÎ³ and PPARÎ± are activated by cinnamon as evidenced by reporter gene assays. These data suggest that cinnamon in its water extract form can act as a dual activator of PPARÎ³ and Î±, and may be an alternative to PPARÎ³ activator in managing obesity-related diabetes and hyperlipidemia."
7. Rafehi H, Ververis K, Karagiannis TC. Controversies surrounding the clinical potential of cinnamon for the management of diabetes. Diabetes Obes Metab. 2011 Nov 16. doi: 10.1111/j.1463-1326.2011.01538.x.
Quick Summary of Study: Extensive in vitro evidence has shown that cinnamon may improve insulin resistance by preventing and reversing impairments in insulin signaling in skeletal muscle. In adipose tissue, it has been shown that cinnamon increases the expression of peroxisome proliferator-activated receptors including, PPARÎ³, which plays a key role in carbohydrate and lipid metabolism. This is comparable to the action of commonly used thiazolinediones drugs, which are PPAR agonists.
"Obesity levels have increased significantly in the past five decades and are predicted to continue rising, resulting in important health implications. In particular, this has translated to an increase in the occurrence of type II diabetes mellitus (T2D). To alleviate associated problems, certain nutraceuticals have been considered as potential adjuncts or alternatives to conventional prescription drugs. Cinnamon, a commonly consumed spice originating from South East Asia, is currently being investigated as a potential preventative supplement and treatment for insulin resistance, metabolic syndrome and T2D. Extensive in vitro evidence has shown that cinnamon may improve insulin resistance by preventing and reversing impairments in insulin signaling in skeletal muscle. In adipose tissue, it has been shown that cinnamon increases the expression of peroxisome proliferator-activated receptors including, PPARÎ³. This is comparable to the action of commonly used thiazolinediones, which are PPAR agonists. Studies have also shown that cinnamon has potent anti-inflammatory properties. However, numerous human clinical trials with cinnamon have been conducted with varying findings. While some studies have showed no beneficial effect, others have indicated improvements in cholesterol levels, systolic blood pressure, insulin sensitivity and postprandial glucose levels with cinnamon. However, the only measurement consistently improved by cinnamon consumption is fasting glucose levels. While it is still premature to suggest the use of cinnamon supplementation based on the evidence, further investigation into mechanisms of action is warranted. Apart from further characterization of genetic and epigenetic changes in model systems, systematic large-scale clinical trials are required. In this study, we discuss the mechanisms of action of cinnamon in the context of T2D and we highlight some of the associated controversies."