Cinnamon Intake Lowers Fasting Blood Glucose: Meta-Analysis

Department of Nutrition, University of California-Davis, Davis, California 95616, USA.
Journal of medicinal food (Impact Factor: 1.63). 04/2011; 14(9):884-9. DOI: 10.1089/jmf.2010.0180
Source: PubMed


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 (-0.49±0.2 mmol/L; n=8, P=.025) and intake of cinnamon extract only also lowered FBG (-0.48 mmol/L±0.17; n=5, P=.008). Thus cinnamon extract and/or cinnamon improves FBG in people with type 2 diabetes or prediabetes.

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    • "The treatment of diabetic subjects with cinnamon was investigated in several clinical trials. While a number of studies demonstrated an improvement in fasting blood glucose concentrations and insulin sensitivity [7]–[8], others did not show any beneficial effects [9]. Notably, cinnamon was not able to exert significant effects in type 1 diabetic patients while its insulin-like effects were present in type 2 diabetic patients [4]. "
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    ABSTRACT: Treatment of diabetic subjects with cinnamon demonstrated an improvement in blood glucose concentrations and insulin sensitivity but the underlying mechanisms remained unclear. This work intends to elucidate the impact of cinnamon effects on the brain by using isolated astrocytes, and an obese and diabetic mouse model. Cinnamon components (eugenol, cinnamaldehyde) were added to astrocytes and liver cells to measure insulin signaling and glycogen synthesis. Ob/ob mice were supplemented with extract from cinnamomum zeylanicum for 6 weeks and cortical brain activity, locomotion and energy expenditure were evaluated. Insulin action was determined in brain and liver tissues. Treatment of primary astrocytes with eugenol promoted glycogen synthesis, whereas the effect of cinnamaldehyde was attenuated. In terms of brain function in vivo, cinnamon extract improved insulin sensitivity and brain activity in ob/ob mice, and the insulin-stimulated locomotor activity was improved. In addition, fasting blood glucose levels and glucose tolerance were greatly improved in ob/ob mice due to cinnamon extracts, while insulin secretion was unaltered. This corresponded with lower triglyceride and increased liver glycogen content and improved insulin action in liver tissues. In vitro, Fao cells exposed to cinnamon exhibited no change in insulin action. Together, cinnamon extract improved insulin action in the brain as well as brain activity and locomotion. This specific effect may represent an important central feature of cinnamon in improving insulin action in the brain, and mediates metabolic alterations in the periphery to decrease liver fat and improve glucose homeostasis.
    Full-text · Article · Mar 2014 · PLoS ONE
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    • "Incubation of blueberry-DSF at 4, 25 and 37 °C for 22 weeks showed no change in concentration of total polyphenols extracted from the matrix (Roopchand et al., 2012). Assessment of randomised, placebo controlled clinical trials with aqueous cinnamon extracts that measured FBG, showed significant effects on lowering FBG (Davis & Yokoyama, 2011). The use of an aqueous extract may provide a higher dose and/or increased bioavailability of bioactive components. "

    Full-text · Dataset · Nov 2013
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    • "This suggests that perturbed glucose/insulin metabolism may be directly or indirectly involved, at least to some extent, in some forms of hypertension. Furthermore, recent meta-analysis also demonstrated that cinnamon intake lowers FPG [18] [19]. We have already demonstrated the effect of cinnamon and its cellular mechanism on blood glucose and BP regulation in patients with T2DM [6] [20]. "
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    ABSTRACT: Objective: To systematically review and evaluate the effect of short term administration of cinnamon on blood pressure regulation in pre and type 2 diabetes patients by performing a meta-analysis of randomized placebo-controlled clinical trials. Research Methods and Procedures: Medical literature for randomized controlled trials (RCTs) of the effect of cinnamon on blood pressure was systematically searched; 3 original articles published from January 2000 to September 2012 were identified from the MEDLINE database and a hand search of the reference lists of the articles obtained through MEDLINE. The search terms included cinnamon or blood pressure or systolic blood pressure (SBP) or diastolic blood pressure (DBP) or diabetes. A random effects model was used to calculate weighted mean difference and 95% confidence intervals (CI). Results: The pooled estimate of the effect of cinnamon intake on systolic and diastolic blood pressure demonstrated that the use of cinnamon significantly decreased SBP and DBP by 5.39 mmHg (95% CI: -6.89, -3.89) and 2.6 mmHg (95% CI: - 4.53, -0.66) respectively. Conclusion: Consumption of cinnamon (short term) is associated with notable reduction of SBP and DBP. Although cinnamon shows hopeful effects on blood pressure lowering potential, it would be premature to recommend cinnamon for blood pressure control, because of the limited number of studies available. Thus, undoubtedly a long term, adequately powered RCTs involving a larger number of patients is needed to appraise the clinical potential of cinnamon on blood pressure control among patients with type 2 diabetes mellitus. Key words: Blood pressure, Diabetes, Cinnamon, Blood glucose, randomized control trials.
    Full-text · Article · May 2013 · Nutrition
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