Cinnamon in glycaemic control: Systematic review and meta analysis

The association between dietary polyphenol intake and the odds of metabolic syndrome

Oxidative stress plays a role in the pathophysiology of metabolic syndrome (MetS), and one of the most important features of polyphenols is their antioxidant properties. However, there is no universal consensus on the effectiveness of polyphenols in treating Mets. Therefore, the present study aimed to investigate the association between polyphenols and MetS in an Iranian sample. This cross-sectional study was conducted on an adult population sample from Shiraz, in southern Iran. MetS was calculated using the criteria of the Adult Treatment Panel III (ATP III), which defines MetS as the presence of three or more of the specified risk factors. A validated food frequency questionnaire (FFQ) was used to measure the participant's food intake. The association between polyphenol intake and the odds on MetS and its components was assessed using logistic regression. In both univariate and multivariate models, the association between polyphenol intake and the risk of MetS was not significant. However, after adjusting for potential confounders in the multivariate model, each unit change in flavonol, flavanone and isoflavones intake was associated with a lower, higher, and higher odds of MetS, respectively (flavonols: odds ratio (OR) = 0.926, 95% confidence interval (CI) 0.891-0.963, P < 0.001-flavanones: OR = 1.007, 95% CI: 1.001-1.014, P = 0.034-isoflavones: OR = 4.920, 95% CI: 1.057-22.894, P = 0.042). Additionally, no significant association was found between polyphenol intake and the risk of MetS components. However, in the multivariate model, after adjusting for potential confounders, a significant association was observed between polyphenol intake and lower odds of high waist circumference (OR = 0.998, 95% CI: 0.996-0.999, P = 0.032). The present study did not reveal a significant association between overall polyphenol intake and the odds of MetS. However, certain subclasses of polyphenols appear to be associated with the likelihood of MetS and its components.

Suppression of the postprandial hyperglycemia in patients with type 2 diabetes by a raw medicinal herb powder is weakened when consumed in ordinary hard gelatin capsules: A randomized crossover clinical trial

INTRODUCTION

Contradictory claims about the efficacy of several medicinal plants to promote glycemic control in patients with type 2 diabetes mellitus (T2DM) have been explained by divergences in the administration form and by extrapolation of data obtained from healthy individuals. It is not known whether the antidiabetic effects of traditional herbal medicines are influenced by gelatin capsules. This randomized crossover trial aimed to evaluate the acute effect of a single dose of raw cinnamon consumed orally either dissolved in water as a beverage or as ordinary hard gelatin capsules on postprandial hyperglycemia (>140 mg/dL; >7.8 mmol/L) in T2DM patients elicited by a nutritionally-balanced meal providing 50 g of complex carbohydrates.

METHODS

Fasting T2DM patients (n = 19) randomly ingested a standardized meal in five experimental sessions, one alone (Control) and the other after prior intake of 3 or 6 g of crude cinnamon in the form of hard gelatin capsules or powder dissolved in water. Blood glucose was measured at fasting and at 0.25, 0.5, 0.75, 1, 1.5 and 2 hours postprandially. After each breakfast, its palatability scores for visual appeal, smell and pleasantness of taste were assessed, as well as the taste intensity sweetness, saltiness, bitterness, sourness and creaminess.

RESULTS

The intake of raw cinnamon dissolved in water, independently of the dose, decreased the meal-induced large glucose spike (peak-rise of +87 mg/dL and Δ1-hour glycemia of +79 mg/dL) and the hyperglycemic blood glucose peak. When cinnamon was taken as capsules, these anti-hyperglycemic effects were lost or significantly diminished. Raw cinnamon intake did not change time-to-peak or the 2-h post-meal glycaemia, but flattened the glycemic curve (lower iAUC) without changing the shape that is typical of T2DM patients.

CONCLUSIONS

This cinnamon's antihyperglycemic action confirms its acarbose-like property to inhibit the activities of the carbohydrate-digesting enzymes α-amylases/α-glucosidases, which is in accordance with its exceptionally high content of raw insoluble fiber. The efficacy of using raw cinnamon as a diabetes treatment strategy seems to require its intake at a specific time before/concomitantly the main hyperglycemic daily meals. Trial registration: Registro Brasileiro de Ensaios Clínicos (ReBEC), number RBR-98tx28b.

Potential Benefit of Spices for Glycemic Control

The prevalence of hyperglycemia is increasing worldwide in large part due to the escalating prevalence of obesity. It can occur along with other disorders and diseases, contributing to escalating health costs and accumulating disabilities. Besides dietary approaches and availability of antidiabetic medications, other complementary approaches and adjunct therapies using biologically active botanical phytochemicals have received growing attention for managing type 2 diabetes mellitus. Spices are one source of these bioactive plant constituents, and considerable preclinical studies have investigated their possible health benefits. There also are an increasing number of human clinical trials assessing the ability of spices and their individual plant constituents to improve glucose homeostasis in those with type 2 diabetes mellitus and other dysglycemic conditions. This narrative review provides a summary of the human studies evaluating the effects of select spices on glucose homeostasis and highlights areas for future research.

Effect of cinnamon spice on continuously monitored glycemic response in adults with prediabetes: a 4-week randomized controlled crossover trial

BACKGROUND

Previous clinical studies showing that cinnamon spice lowers blood glucose concentrations had inconsistent results.

OBJECTIVES

To determine the effect of daily cinnamon spice supplementation in an amount commonly used for seasoning on glucose concentrations in adults with obesity and prediabetes.

METHODS

Following a 2-wk run-in period of maintaining a low polyphenol/fiber diet, 18 participants with obesity and prediabetes underwent a 10-wk randomized, controlled, double-blind, crossover trial (mean age 51.1 y; mean fasting plasma glucose 102.9 mg/dL). The participants were randomly assigned to take cinnamon (4 g/d) or placebo for 4-wk, followed by a 2-wk washout period, and then crossed over to the other intervention for an additional 4-wk. Glucose changes were measured with continuous glucose monitoring. Oral glucose tolerance testing immediately following ingestion of cinnamon or placebo was performed at 4-time points to assess their acute effects both at the baseline and end of each intervention phase. Digestive symptom logs were obtained daily.

RESULTS

There were 694 follow-up days with 66,624 glucose observations. When compared with placebo, 24-h glucose concentrations were significantly lower when cinnamon was administered [mixed-models; effect size (ES) = 0.96; 95 % confidence interval (CI): -2.9, -1.5; P < 0.001]. Similarly, the mean net-area-under-the-curve (netAUC) for glucose was significantly lower than for placebo when cinnamon was given (over 24 h; ES = -0.66; 95 % CI: 2501.7, 5412.1, P = 0.01). Cinnamon supplementation resulted in lower glucose peaks compared with placebo (Δpeak 9.56 ± 9.1 mg/dL compared with 11.73 ± 8.0 mg/dL; ES = -0.57; 95 % CI: 0.8, 3.7, P = 0.027). Glucose-dependent-insulinotropic-polypeptide concentrations increased during oral glucose tolerance testing + cinnamon testing (mixed-models; ES = 0.51; 95 % CI: 1.56, 100.1, P = 0.04), whereas triglyceride concentrations decreased (mixed-models; ES = 0.55; 95 % CI: -16.0, -1.6, P = 0.02). Treatment adherence was excellent in both groups (cinnamon: 97.6 ± 3.4 % compared with placebo: 97.9 ± 3.7 %; ES = -0.15; 95 % CI: -1.8, 0.2, P = 0.5). No differences were found in digestive symptoms (abdominal pain, borborygmi, bloating, excess flatus, and stools/day) between cinnamon and placebo groups.

CONCLUSIONS

Cinnamon, a widely available and low-cost supplement, may contribute to better glucose control when added to the diet in people who have obesity-related prediabetes. This trial was registered at clinicaltrials.gov as NCT04342624.

The metabolic effect of Momordica charantia cannot be determined based on the available clinical evidence: a systematic review and meta-analysis of randomized clinical trials

Several studies have shown that Momordica charantia L. (Cucurbitaceae, bitter melon) has beneficial effects on metabolic syndrome (MetS) parameters and exerts antidiabetic, anti-hyperlipidemic, and anti-obesity activities. Since the findings of these studies are contradictory, the goal of this systematic review and meta-analysis was to assess the efficacy of bitter melon in the treatment of metabolic syndrome, with special emphasis on the anti-diabetic effect. Embase, Cochrane, PubMed, and Web of Science databases were searched for randomized controlled human trials (RCTs). The meta-analysis was reported according to the PRISMA statement. The primary outcomes of the review are body weight, BMI, fasting blood glucose, glycated hemoglobin A1c, systolic blood pressure, diastolic blood pressure, serum triglyceride, HDL, LDL, and total cholesterol levels. Nine studies were included in the meta-analysis with 414 patients in total and 4-16 weeks of follow-up. In case of the meta-analysis of change scores, no significant effect could be observed for bitter melon treatment over placebo on fasting blood glucose level (MD = -0.03; 95% CI: -0.38 to 0.31; I2 = 34%), HbA1c level (MD = -0.12; 95% CI: -0.35 to 0.11; I2 = 56%), HDL (MD = -0.04; 95% CI: -0.17 to 0.09; I2 = 66%), LDL (MD = -0.10; 95% CI: -0.28 to 0.08; I2 = 37%), total cholesterol (MD = -0.04; 95% CI: -0.17 to 0.09; I2 = 66%,), body weight (MD = -1.00; 95% CI: -2.59-0.59; I2 = 97%), BMI (MD = -0.42; 95% CI: -0.99-0.14; I2 = 95%), systolic blood pressure (MD = 1.01; 95% CI: -1.07-3.09; I2 = 0%) and diastolic blood pressure levels (MD = 0.24; 95% CI: -1.04-1.53; I2 = 0%). Momordica treatment was not associated with a notable change in ALT, AST, and creatinine levels compared to the placebo, which supports the safety of this plant. However, the power was overall low and the meta-analyzed studies were also too short to reliably detect long-term metabolic effects. This highlights the need for additional research into this plant in carefully planned clinical trials of longer duration.

A Scoping Review of the Clinical Evidence for the Health Benefits of Culinary Doses of Herbs and Spices for the Prevention and Treatment of Metabolic Syndrome

Metabolic syndrome (MetS) is a growing global health problem. Evidence suggests that diets rich in phytochemical-containing herbs and spices can contribute to reducing the risk of chronic diseases. This review assesses the scope of evidence supporting the use of herbs and spices in the diet for the prevention or treatment of MetS and its associated health conditions. A search of the PubMed, Scopus and Google Scholar databases was carried out to assess the available clinical evidence for culinary doses of commonly used herbs and spices. Trials that were measuring health factors related to metabolic disorders in healthy individuals, or the health of individuals with MetS or associated diseases, were included. Out of a total of 1738 papers identified, there were 142 relevant studies on black pepper, chilli, cardamom, cinnamon, coriander, cumin, fennel, fenugreek, garlic, ginger, nigella seed, rosemary, sage and turmeric. No relevant research was found for cloves, mint, oregano, parsley or thyme. Cinnamon, fenugreek and ginger were the herbs/spices with the most published trials on them and that showed promise for glycaemic control. Cardamom appears to have potential to reduce inflammatory markers, and cinnamon, ginger and turmeric to reduce blood lipids. Patients with type 2 diabetes were the population most likely to be included in studies, but the preventative benefits of herbs/spices in healthy populations were also investigated, particularly for chilli, ginger and cinnamon. There is evidence for the beneficial effect of culinary doses of many common herbs/spices in the prevention and treatment of MetS and associated disorders.

Cinnamon modulates the pharmacodynamic & pharmacokinetic of amlodipine in hypertensive rats

The objective of this study was to investigate the effects of cinnamon on the pharmacodynamic (PD) & pharmacokinetic (PK) of amlodipine in hypertensive rats. The hypertensive control group of Wistar rats received L-NAME (40 mg/kg, daily, orally) only. The cinnamon group of rats was treated with cinnamon (200 mg/kg, daily, orally) along with L-NAME. Following 14 days treatment period, blood pressures of rats were monitored at designated intervals over 24 h utilizing a tail-cuff system for measuring blood pressure. To assess the oral PK; amlodipine was administered as a single oral dose of 1 mg/kg to rats and blood samples were collected at specified intervals over 24 h and analysed by UPLC-LC MS/MS. Synergistic decreased in rat's blood pressure was observed in presence of cinnamon + amlodipine. Simultaneous administration of cinnamon ameliorates the Cmax and AUC0-t of amlodipine, the Cmax and AUC0-t was 11.04 ± 1.01 ng/ml and 113.76 ± 5.62 ng h/ml for the cinnamon + amlodipine group as compared to 4.12 ± 0.49 ng/ml and 48.59 ± 4.28 ng h/ml for the amlodipine alone group. The study demonstrates that the use of cinnamon considerably decreases the blood pressure levels and enhances the PK parameters of amlodipine in hypertensive rats.

The effect of cinnamon supplementation on glycemic control in patients with type 2 diabetes or with polycystic ovary syndrome: an umbrella meta-analysis on interventional meta-analyses

BACKGROUND

Several meta-analyses reported glycemic-lowering effects of cinnamon, while others reported conflicting findings. In the present study, we aimed to perform an umbrella meta-analysis of previous interventional meta-analyses on the effects of cinnamon on glycemic control in patients with type 2 diabetes (T2D) or with polycystic ovary syndrome (PCOS).

METHODS

Relevant studies were searched in PubMed, Scopus, EMBASE, Web of Science, and Google Scholar up to June 2022. Meta-analyses of randomized clinical trials (RCTs) investigating the effects of cinnamon on glycemic indices including fasting plasma glucose (FPG), homeostatic model assessment for insulin resistance (HOMA-IR), insulin, and hemoglobin A1C (HbA1c) were included. Random-effects models were used to perform the umbrella meta-analysis and pool the weighted mean difference (WMD) or standardized mean difference (SMD) and their 95% confidence intervals (CI).

RESULTS

Overall, 11 meta-analyses of RCTs were included. Cinnamon supplementation was effective in reducing serum FPG (WMD: -10.93 mg/dL; 95%CI: -16.22, -5.65; SMD: -0.86; 95%CI: -1.19, -0.52), insulin (WMD: -2.01 IU/mL; 95%CI: -3.96, -0.07; SMD: -0.61; 95%CI: -0.93, -0.30), HOMA-IR levels (WMD: -0.61; 95%CI: -0.91, -0.31; SMD: -0.78; 95%CI: -1.26, -0.30), and HbA1c (WMD: -0.10%; 95%CI: -0.17, -0.03).

CONCLUSION

Cinnamon can be used as an anti-diabetic agent and an add-on treatment to control glycemic indices among patients with T2D or PCOS.

Cinnamaldehyde supplementation acts as an insulin mimetic compound improving glucose metabolism during adolescence, but not during adulthood, in healthy male rats

PURPOSE

Adolescence is a critical period of increased vulnerability to nutritional modifications, and adolescents may respond differently from adults to dietary intake and nutraceuticals. Cinnamaldehyde, a major bioactive compound of cinnamon, improves energy metabolism, as has been shown in studies conducted primarily in adult animals. We hypothesized that cinnamaldehyde treatment may have a higher impact on the glycemic homeostasis of healthy adolescent rats than on healthy adult rats.

METHODS

Male adolescent (30 days) or adult (90 days) Wistar rats received cinnamaldehyde (40 mg/kg) for 28 days by gavage. The oral glucose tolerance test (OGTT), liver glycogen content, serum insulin concentration, serum lipid profile, and hepatic insulin signaling marker expression were evaluated.

RESULTS

Cinnamaldehyde-treated adolescent rats showed less weight gain (P = 0.041), improved OGTT (P = 0.004), increased expression of phosphorylated IRS-1 (P = 0.015), and a trend to increase phosphorylated IRS-1 (P = 0.063) in the liver of adolescent rats in the basal state. None of these parameters was modified after treatment with cinnamaldehyde in the adult group. Cumulative food intake, visceral adiposity, liver weight, serum insulin, serum lipid profile, hepatic glycogen content, and liver protein expression of IRβ, phosphorylated IRβ, AKT, phosphorylated AKT, and PTP-1B in the basal state were similar between both age groups.

CONCLUSION

In a healthy metabolic condition, cinnamaldehyde supplementation affects glycemic metabolism in adolescent rats while promoting no changes in adult rats.

Cinnamon: an aromatic condiment applicable to chronic kidney disease

Cinnamon, a member of the Lauraceae family, has been widely used as a spice and traditional herbal medicine for centuries and has shown beneficial effects in cardiovascular disease, obesity, and diabetes. However, its effectiveness as a therapeutic intervention for chronic kidney disease (CKD) remains unproven. The bioactive compounds within cinnamon, such as cinnamaldehyde, cinnamic acid, and cinnamate, can mitigate oxidative stress, inflammation, hyperglycemia, gut dysbiosis, and dyslipidemia, which are common complications in patients with CKD. In this narrative review, we assess the mechanisms by which cinnamon may alleviate complications observed in CKD and the possible role of this spice as an additional nutritional strategy for this patient group.

Effectiveness and Safety of Ayurvedic Medicines in Type 2 Diabetes Mellitus Management: A Systematic Review and Meta-Analysis

Introduction: Many Ayurvedic medicines have the potential for managing type 2 diabetes mellitus (T2DM), with previous systematic reviews demonstrating effectiveness and safety for specific Ayurvedic medicines. However, many of the reviews need updating and none provide a comprehensive summary of all the Ayurvedic medicines evaluated for managing T2DM. Objective: The objective of this systematic review was to evaluate and synthesize evidence on the effectiveness and safety of Ayurvedic medicines for managing T2DM. Inclusion criteria: Published and unpublished RCTs assessing the effectiveness and safety of Ayurvedic medicines for managing T2DM in adults. Methods: The JBI systematic review methodology was followed. A comprehensive search of sources (including 18 electronic databases) from inception to 16 January 2021 was made. No language restrictions were applied. Data synthesis was conducted using narrative synthesis and random effects meta-analyses, where appropriate. Pooled results are reported as mean differences (MD) with 95% confidence intervals (CI). Results: Out of 32,519 records identified from the searches, 219 articles were included in the systematic review representing 199 RCTs (21,191 participants) of 98 Ayurvedic medicines. Overall, in the studies reviewed the methodology was not adequately reported, resulting in poorer methodological quality scoring. Glycated hemoglobin (HbA1c) was reduced using Aegle marmelos (L.) Corrêa (MD -1.6%; 95% CI -3 to -0.3), Boswellia serrata Roxb. (-0.5; -0.7 to -0.4), Gynostemma pentaphyllum (Thunb.) Makino (-1; -1.5 to -0.6), Momordica charantia L. (-0.3; -0.4 to -0.1), Nigella sativa L. (-0.4; -0.6 to -0.1), Plantago ovata Forssk. (-0.9; -1.4 to -0.3), Tinospora cordifolia (Willd.) Hook.f. and Thomson (-0.5; -0.6 to -0.5), Trigonella foenum-graecum L. (-0.6; -0.9 to -0.4), and Urtica dioica L. (-1.3; -2.4 to -0.2) compared to control. Similarly, fasting blood glucose (FBG) was reduced by 4-56 mg/dl for a range of Ayurvedic medicines. Very few studies assessed health-related quality of life (HRQoL). Adverse events were not reported in many studies, and if reported, these were mostly none to mild and predominately related to the gastrointestinal tract. Conclusion: The current evidence suggests the benefit of a range of Ayurvedic medicines in improving glycemic control in T2DM patients. Given the limitations of the available evidence and to strengthen the evidence base, high-quality RCTs should be conducted and reported.

Mechanisms for Improving Hepatic Glucolipid Metabolism by Cinnamic Acid and Cinnamic Aldehyde: An Insight Provided by Multi-Omics

Cinnamic acid (AC) and cinnamic aldehyde (AL) are two chemicals enriched in cinnamon and have been previously proved to improve glucolipid metabolism, thus ameliorating metabolic disorders. In this study, we employed transcriptomes and proteomes on AC and AL treated db/db mice in order to explore the underlying mechanisms for their effects. Db/db mice were divided into three groups: the control group, AC group and AL group. Gender- and age-matched wt/wt mice were used as a normal group. After 4 weeks of treatments, mice were sacrificed, and liver tissues were used for further analyses. Functional enrichment of differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) were performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. DEPs were further verified by parallel reaction monitoring (PRM). The results suggested that AC and AL share similar mechanisms, and they may improve glucolipid metabolism by improving mitochondrial functions, decreasing serotonin contents and upregulating autophagy mediated lipid clearance. This study provides an insight into the molecular mechanisms of AC and AL on hepatic transcriptomes and proteomes in disrupted metabolic situations and lays a foundation for future experiments.

Safety of Cinnamon: An Umbrella Review of Meta-Analyses and Systematic Reviews of Randomized Clinical Trials

Purpose: Many evidence-based studies have indicated that cinnamon has therapeutic effects. However, it may not be entirely safe and its adverse effects may be ignored. The present umbrella review was conducted to elucidate the safety of cinnamon.

Methods: Pertinent meta-analyses and systematic reviews of randomized controlled trials on cinnamon use in humans were identified by searching PubMed, EMBASE, and the Cochrane Library from their inception to September 15, 2021. All meta-analyses and systematic reviews on the safety or adverse effects of cinnamon were considered. PRISMA 2020 was used as the standard of reporting (PRISMA registration ID: 286746).

Results: We identified three meta-analyses and one systematic review that described the safety of cinnamon. The quality of the meta-analysis and systematic reviews was evaluated using “Assessing the Methodological Quality of Systematic Reviews.” Their quality was rated as low in two (50%) instances and moderate in two (50%). There were no significant toxic- or side effects between cinnamon group and placebo group regardless of dose and duration.

Conclusion: There is evidence to support that the use of cinnamon has no adverse reactions. It can improve the health status of patients as an adjuvant treatment. Future studies exploring better profile risks and protective factors for cinnamon use-related adverse effect are needed, in order that preventive approaches can be developed.

Association Between Cinnamon Consumption and Risk of Cardiovascular Health: A Systematic Review and Meta-Analysis

BACKGROUND

Cinnamon has been used as a traditional herbal medication for decades. Several studies have investigated cinnamon consumption and cardiovascular risk. So far, the evidence remains inconclusive. Thus, we aim to systematically review the currently available literature and quantify the evidence, if possible.

METHODS

We systematically searched Ovid MEDLINE, Ovid Embase, Ovid Cochrane Database of Systematic Reviews, Scopus, and Web of Science from database inception in 1966 through December 2020. The exposure of interest was cinnamon consumption, the outcome was cardiovascular risk defined as hemoglobin A1C, low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c). Two investigators independently reviewed the data. Conflicts were resolved through consensus. Random-effects meta-analyses were used.

RESULTS

Of 23 studies (1070 subjects), the included studies were heterogeneous, generally of very poor quality. We found no difference in LDL-c levels in patients who consumed cinnamon vs those who did not, with a weighted mean difference (WMD) of 0.38 (confidence interval [CI], -6.07-6.83). We also found no difference in HDL-c between the 2 groups with WMD 0.40 (CI, -1.14-1.94). In addition, we found no statistical differences in hemoglobin A1C between the 2 groups with WMD of 0.0 (CI, -0.44-0.45).

CONCLUSIONS

Our meta-analysis suggests that there is no association between cinnamon consumption and differences in LDL-c, HDL-c, and hemoglobin A1C levels. Further randomized control trials studies using a robust design with long-term cinnamon consumption are needed to further investigate any potential effect.

What is the influence of cinnamon supplementation on liver enzymes? A systematic review and meta-analysis of randomized controlled trials

Existing evidence has uncovered the potential health benefits of cinnamon intake; however, its effect on liver function is unclear. Thus, the aim of this systematic review and meta-analysis was to examine the effect of cinnamon supplementation on liver enzymes. Relevant articles were identified through a systematic search in PubMed/Medline, Scopus, Web of Science, Cochrane Library, and Embase up to September 2020. All trials assessing the effect of oral cinnamon supplementation on serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) in adults were included. The pooled effect sizes were obtained using the random-effects model and expressed as mean difference (MD) and 95% confidence intervals (CI). A total of seven original trials (nine treatment arms) involving a total of 256 subjects were included in the final analysis. The pooled analysis indicated that cinnamon supplementation had no significant effect on serum levels of ALT, AST, and ALP. However, there was a significant reduction in ALT levels in patients with type 2 diabetes (MD: -4.01 U/L; 95% CI: -6.86, -1.15) and in trials with low-dose supplementation (<1,500 mg/d), follow-up duration longer than 12 weeks, and in the elderly patients (aged>50 years). The beneficial effects of cinnamon intake were also shown in AST levels in patients with type 2 diabetes and trials with long-term follow-up (>12 weeks). Longer-term, oral cinnamon supplementation may improve serum levels of liver enzymes in patients with type 2 diabetes. Further high-quality studies are needed, especially in populations with abnormal liver enzyme levels, to firmly establish the clinical efficacy of cinnamon on liver function.

The effect of herbs and spices on risk factors for cardiometabolic diseases: a review of human clinical trials

Herbs and spices are recommended to increase flavor and displace salt in the diet. Accumulating evidence suggests herbs and spices may improve risk factors for cardiometabolic diseases. In this narrative review, an overview of evidence from human clinical trials examining the effect of herbs and spices on risk factors for cardiometabolic diseases is provided. Human clinical trials examining supplemental doses of individual spices and herbs, or the active compounds, have yielded some evidence showing improvements to lipid and lipoprotein levels, glycemic control, blood pressure, adiposity, inflammation, and oxidative stress. However, cautious interpretation is warranted because of methodological limitations and substantial between-trial heterogeneity in the findings. Evidence from acute studies suggests intake of mixed herbs and spices as part of a high-saturated fat, high-carbohydrate meal reduces postprandial metabolic impairments, including lipemia, oxidative stress, and endothelial dysfunction. Limited studies have examined the postprandial metabolic effects of incorporating mixed herbs and spices into healthy meals, and, to our knowledge, no trials have assessed the effect of longer-term intake of mixed herbs and spices on risk factors for cardiometabolic diseases. To inform evidence-based guidelines for intake of herbs and spices for general health and cardiometabolic disease risk reduction, rigorously conducted randomized controlled trials are needed, particularly trials examining herb and spice doses that can be incorporated into healthy dietary patterns.

The effect of cinnamon supplementation on liver enzymes in adults: A systematic review and meta-analysis of randomized controlled trials

AIMS

The aim of this study was to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) to examine the effect of cinnamon supplementation on liver enzymes.

METHODS

A systematic search was performed in electronic databases including PubMed-Medline, Scopus, and ISI Web of Science up to November 2020. We used a random effects model to estimate pooled effect size of alanine aminotransferase (ALT), alkaline phosphatase (ALP), and aspartate aminotransferase (AST) levels.

RESULTS

Seven RCTs (9 treatment arms) fulfilled the eligibility criteria of the present meta-analysis. Overall, meta-analysis could not show any beneficial effect of cinnamon supplementation on AST, ALT, and ALP. Subgroup analyses showed that the effect of cinnamon supplementation on ALT was significant at the dosages of <1500 mg/day (Hedges's: -0.61; 95 % CI: -1.11, -0.10; P = 0.002), in trials lasting>12 weeks (Hedges's: -0.83; 95 % CI: -1.36, -0.30; P = 0.01), and in trials conducted of both gender (Hedges's: -0.72; 95 % CI: -1.45, -0.01; P = 0.04).

CONCLUSION

In summary, cinnamon supplementation had no significant effect on liver enzymes in adults. However, the effect of cinnamon on ALT levels was significant at the dosages of <1500 mg/day, in trials lasting>12 weeks, and in trials conducted of both gender. Nevertheless, further studies should be performed to confirm our results.

The effect of cinnamon supplementation on glycemic control in women with polycystic ovary syndrome: A systematic review and meta-analysis

Several clinical trials have identified glycemic-lowering effects of cinnamon, while other studies have reported conflicting findings. A comprehensive systematic search on Embase, PubMed, Scopus, Web of Science, and Cochrane Library was conducted using defined keywords in any language through June 2020. Studies that compared the effect of cinnamon with placebo on insulin resistance (IR) indices, as the primary outcome, in women with polycystic ovary syndrome (PCOS) were considered eligible. Standard Mean difference (SMD) (with 95% confidence intervals) for endpoints were calculated using the random-effects model. Finally, five RCTs which met the criteria were included in the meta-analysis. After pooling data, cinnamon supplementation significantly reduced homeostatic model assessment for insulin resistance (HOMA-IR) scores in women with PCOS (SMD: -0.84, 95% CI: -1.52, -0.16, p = .010). Cinnamon supplementation likely improves certain IR markers in patients with PCOS. PRACTICAL APPLICATIONS: There are controversies reports for cinnamon intake, which animal models have suggested that it decreases IR via promotion of insulin action, stimulating insulin signaling pathways, and enhancing insulin sensitivity. This study provides comprehensive information about the effect of cinnamon on insulin resistance (IR) indices in women with PCOS. In this regard, our results indicated that cinnamon supplementation significantly reduced homeostatic model assessment for insulin resistance (HOMA-IR) scores in women with PCOS. Therefore, consumption of cinnamon can be safe and this can be a useful recommendation for improving IR and promotion of healthy life which indeed are the potential or actual uses of this research.

What is the Impact of Cinnamon Supplementation on Blood Pressure? A Systematic Review and Meta-Analysis

AIM

This study was designed to make a systematic review and meta-analysis on randomized controlled trials (RCTs) assessing the effect of cinnamon on blood pressure (BP).

METHODS

A systematic computerized literature search of PubMed, Scopus, Web of Science, Cochrane Library and Google Scholar databases was conducted up to August 2019. All RCTs using cinnamon supplements in adults were included in this systematic review and meta-analysis.

RESULTS

Out of 927 records, 8 trials that enrolled 582 participants were included. The pooled effect size showed that SBP did not change following cinnamon supplementation. (WMD: -0.61mmHg; 95% CI: -1.36, 0.14, P= 0.111). Also cinnamon supplementation in long-duration (≥ 8weeks) had a significant effect on SBP (WMD: -1.25 mmHg; 95% CI: -2.22, -0.28, P= 0.012). Pooled analysis showed that cinnamon had a significant effect on DBP (WMD: -0.93mmHg, 95% CI: -1.55 to -0.32, P= 0.003). In addition, results from both duration subsets and high dose (>1500 mg/day) of cinnamon supplementation were significant.

CONCLUSION

Our findings revealed that cinnamon supplementation has favorable effects on DBP although results of SBP were not the same. Nonetheless, further studies are required.

Nutraceuticals: Reviewing their Role in Chronic Disease Prevention and Management

Over half the adult population in many Western countries consume nutraceuticals because of their purported therapeutic benefits, accessibility and convenience. Several studies have demonstrated that they may also serve as a useful adjunct to pharmaceuticals to better manage chronic conditions or offset negative side effects. Individuals are advised to consult their physician before using nutraceuticals, but this advice is often overlooked. Thus, the community pharmacist plays an increasingly important role in assisting consumers with selecting a nutraceutical that is safe and for which there is evidence of therapeutic efficacy. Therefore, the aim of this review is to summarise the clinical evidence, safety and purported mechanisms of action for selected nutraceuticals in the management of chronic diseases, including obesity, diabetes, hypertension, hypercholesterolemia and inflammatory-based diseases.

Analysis of the Efficacy of Cinnamon for Patients with Diabetes Mellitus Type II Based on Traditional Persian Medicine Syndrome Differentiation: A Randomized Controlled Trial

Background: Conflicting results have been obtained from the studies on the hypoglycemic effect of cinnamon in patients with diabetes mellitus type II (T2DM). Objectives: This research aimed at assessing the effect of applying the syndrome differentiation model based on traditional Persian medicine (TPM) to identify the patients who benefit more from cinnamon supplementation. Methods: This study was a randomized, triple-blind, placebo-controlled trial based on a parallel design. One hundred and forty eligible patients referring to the Diabetes Clinic of Yazd University of Medical Sciences, who were diagnosed with T2DM, were randomly divided into the cinnamon and placebo groups. Then, 500-mg capsules of cinnamon bark powder or placebo were administered to them twice a day for three months. All the participants completed a standard questionnaire for syndrome diagnosis in traditional Persian medicine (TPM). Fasting plasma glucose (FPG), glycated hemoglobin (HbA1C), fasting insulin (FI), and insulin resistance (IR), calorie intake, and physical activity were measured before and after the interventions. The glycemic outcomes were analyzed according to the TPM syndrome. Results: There was no statistically significant difference between the patients’ demographic and clinical features in the two groups. Glycemic indices were improved in patients receiving cinnamon supplementation compared to placebo group (-13.1 ± 1.7, -1.7 ± 1.9, P < 0.001 for change in FPG and -0.27 ± 0.039 vs. 0.001 ± 0.019, P < 0.001 for change in HbA1C respectively). All the outcomes were more improved in the patients with wet syndrome compared to dry ones, which was compatible with Persian syndrome differentiation (P < 0.05). Conclusions: Diabetic patients with wet syndrome based on TPM benefit more form cinnamon supplementation.

The Effect of Heat Stress on Respiratory Alkalosis and Insulin Sensitivity in Cinnamon Supplemented Pigs

With increases in the frequency, intensity and duration of heat waves forecast plus expansion of tropical agriculture, heat stress (HS) is both a current and an emerging problem. As cinnamon has been shown to increase insulin sensitivity, which is part of the adaptive response to HS, the aim of this experiment was to determine if cinnamon could improve insulin sensitivity and ameliorate HS in grower pigs. In a 2 × 2 factorial design, 36 female Large White × Landrace pigs were fed control (0%) vs. cinnamon (1.5%) diets and housed for 7 day under thermoneutral (20 °C, TN) vs. HS conditions (8 h 35 °C/16 h 28 °C, 35% relative humidity). At the completion of the challenge, insulin sensitivity was assessed by an intravenous glucose tolerance test (IVGTT). Heat stress increased parameters such as respiration rate and rectal temperature. Furthermore, biochemical changes in blood and urine indicated the pigs were experiencing respiratory alkalosis. Minimal modelling of parameters of insulin sensitivity showed that HS pigs had a lower insulin response to the IVGTT and improved insulin sensitivity. Cinnamon had additive effects with heat stress, reflected in lowering the insulin area under curve (AUC) and elevated insulin sensitivity compared to TN. However, this apparent improvement in insulin sensitivity did not ameliorate any of the other physiological symptoms of HS.

The role of nutraceuticals in prevention and treatment of hypertension: An updated review of the literature

Hypertension (HTN) is a worldwide epidemic in both developed and developing countries. It is one of the leading causes of major health problems such as cardiovascular disease, stroke, and heart attack. In recent years, several studies have reported associations between specific dietary ingredients and improving HTN. Nutraceuticals are natural food components with pharmacological properties. Reports suggest that functional foods and nutraceutical ingredients might support patients to obtain the desired therapeutic blood pressure (BP) goals and reduce cardiovascular risks by modulating various risk factors such as oxidative stress, renin-angiotensin system hyperactivity, inflammation, hyperlipidemia, and vascular resistance. We review the recent clinical experiments that have evaluated the biological and pharmacological activities of several types of nutraceuticals, including sour tea, cocoa, common spices, vitamin C, vitamin E, lycopene, flavonoids, coenzyme Q10, milk's tripeptides, calcium, magnesium, polyunsaturated fatty acids, and prebiotics in preventing and treating HTN. This review summarizes recent knowledge about the impact of common nutraceuticals for the regulation of BP.

Efficacy and safety of cinnamon in type 2 diabetes mellitus and pre-diabetes patients: A meta-analysis and meta-regression

INTRODUCTION

Cinnamon has been used as a dietary component and in the management of diabetes mellitus. This study systematically reviewed and synthesized evidence on the efficacy of cinnamon for the treatment of type 2 diabetes mellitus (T2DM) and pre-diabetes patients.

METHODS

Databases of Web of Sciences, the Cochrane library, PubMed, CINAHL and SCOPUS were searched. Stata version 13 (College Station, Texas 77845 USA) and RevMan var. 5.3 software were used for meta-analysis. Heterogeneity was assessed using Chi-square and I² tests.

RESULTS

Sixteen randomized controlled studies were included in the meta-analysis. Cinnamon significantly reduced fasting blood glucose (FBG) and homeostatic model assessment for insulin resistance (HOMA-IR) level compared to placebo with weighted mean difference (WMD) of -0.545 (95% CI: -0.910, -0.18) mmol/L, I² = 83.6% and -0.714(-1.388, -0.04), I² = 84.4% respectively. There was no significant change in weighted mean difference of glycosylated hemoglobin A1C (HbA1c) % and lipid profiles (mmol/L). Meta-regression did not show any factor significantly affecting the treatment response.

CONCLUSION

Cinnamon reduced FBG and HOMA-IR, level in T2DM and pre-diabetes patients compared to placebo. High heterogeneity observed among included studies warrants further clinical trials after standardization of cinnamon formulation.

Natural Hydrogen Sulfide Donors from Allium sp. as a Nutraceutical Approach in Type 2 Diabetes Prevention and Therapy

Type 2 diabetes mellitus (DM) is a socially relevant chronic disease with high prevalence worldwide. DM may lead to several vascular, macrovascular, and microvascular complications (cerebrovascular, coronary artery, and peripheral arterial diseases, retinopathy, neuropathy, and nephropathy), often accelerating the progression of atherosclerosis. Dietary therapy is generally considered to be the first step in the treatment of diabetic patients. Among the current therapeutic options, such as insulin therapy and hypoglycemic drugs, in recent years, attention has been shifting to the effects and properties-that are still not completely known-of medicinal plants as valid and inexpensive therapeutic supports with limited side effects. In this review, we report the relevant effects of medicinal plants and nutraceuticals in diabetes. In particular, we paid attention to the organosulfur compounds (OSCs) present in plant extracts that due to their antioxidant, hypoglycemic, anti-inflammatory, and immunomodulatory effects, can contribute as cardioprotective agents in type 2 DM. OSCs derived from garlic (Allium sp.), due to their properties, can represent a valuable support to the diet in type 2 DM, as outlined in this manuscript based on both in vitro and in vivo studies. Moreover, a relevant characteristic of garlic OSCs is their ability to produce the gasotransmitter H₂S, and many of their effects can be explained by this property. Indeed, in recent years, several studies have demonstrated the relevant effects of endogenous and exogenous H₂S in human DM, including by in vitro and in vivo experiments and clinical trials; therefore, here, we summarize the effects and the underlying molecular mechanisms of H₂S and natural H₂S donors.

Assessment of Human Health Risk of Toxic Elements Due to Cinnamon Ingestion in the Diet

Recent studies highlighted the beneficial action of cinnamon on postprandial glycemia and LDL-cholesterol concentrations, both in healthy subjects and type 2 diabetic patients. Inclusion of 3 to 6 g of cinnamon in diet revealed a beneficial effect on glucose metabolism control in non-diabetic adults during postprandial period. Given the levels of toxic elements present in cinnamon species from different countries, such large daily intakes of cinnamon can easily exceed their maximum permissible limits and, consequently, induce adverse health effects. This study aimed to investigate the elemental concentration profile in cinnamon powder products available in the Portuguese market and to assess the cumulative non-carcinogenic risk to human health due to the exposure to mixtures of such elements through the inclusion of 6 g of cinnamon in diet. Concentrations of Cu, Zn, Fe, Al, Cl, Mn, and Sr were determined by wavelength dispersive X-ray fluorescence spectroscopy in different lots of eight branded and one bulk cinnamon powder products. Linear mixed models have revealed significant differences in concentrations of Zn, Fe, Al, and Cl between brands. In particular, bulk cinnamon samples presented the highest contents of Fe (475.0-490.0 mg kg^-1) and Al (1139.0-1336.0 mg kg^-1). The non-carcinogenic risk was assessed following EPA's guidelines through the hazard quotient (HQ). Estimated HQ values were lower than the USEPA guideline of 1. Additionally, the hazard index (HI), representing the combined non-carcinogenic effects of all toxic elements, revealed no potential human health risk for heavy consumers of cinnamon (HI = 0.660). AbstractGraphical ᅟ.

The Effect of Different Amounts of Cinnamon Consumption on Blood Glucose in Healthy Adult Individuals

Background

This study was aimed at investigating the effect of consumption of different amounts of cinnamon on preprandial blood glucose (PrBG), postprandial blood glucose (PoBG), glycosylated hemoglobin (HbA1c), and body mass index (BMI).

Methods

This study was carried out on 41 healthy adult individuals. The individuals were divided into 3 groups and monitored for 40 days. The first, second, and third groups were given 1 g/day, 3 g/day, and 6 g/day cinnamon, respectively. Before the beginning of the consumption of cinnamon, HbA1c and PrBG blood tests of the individuals were examined on an empty stomach at family practice centers. Two hours after these tests were carried out and breakfast, PoBG tests were performed.

Results

According to the findings of the study, the differences between the average weight measurements, BMI values, and HbA1c values before consumption on days 20 and 40 were not statistically significant in the individuals consuming 1 g, 3 g, and 6 g of cinnamon a day. The difference between the average PrBG measurements was found to be significant in the individuals consuming 6 g of cinnamon per day. The difference between the average PoBG measurements before consumption on days 20 and 40 was significant in the individuals consuming 1 g, 3 g, and 6 g of cinnamon per day.

Conclusions

In particular a 3–6 g of cinnamon consumption was found to affect certain blood parameters of individuals positively. Therefore, it is considered to be beneficial to raise awareness of individuals to be conscious to regularly consume cinnamon.

Cinnamon supplementation positively affects obesity: A systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND & AIMS

Data about the effects of cinnamon supplementation on obesity measures are conflicting. This systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to summarize the effects of cinnamon intake on body weight (BW), Body Mass Index (BMI), Waist Circumference (WC), and fat mass (FM) in adults.

METHODS

Online electronic search engines including PubMed, SCOPUS, Cochrane Library, and Google Scholar were searched to find pertinent articles until September 2018. Data were pooled using the random-effects method and were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI). The non-linear association was assessed using fractional polynomial modeling.

RESULTS

Out of 679 records, 12 trials that enrolled 786 subjects were included. The pooled results showed that cinnamon administration significantly decreased BW (WMD: -1.02 kg, 95% CI: -1.66 to -0.38, P = 0.002), BMI (WMD: -0.51 kg/m², 95% CI: -0.74, -0.28, P < 0.001), WC (WMD: -2.40 cm, 95% CI: -4.48, -0.33, P = 0.02), and FM (WMD: -1.02%, 95% CI: -1.80, -0.24, P = 0.01). Greater effects on BW were observed in subjects aged <50 years old and those with a baseline BMI of ≥30 kg/m². The cinnamon administrations significantly reduced FM at the dosages of ≥2 g/d, when administered for ≥12 weeks. Cinnamon administration resulted in BW and WC reduction in non-linear fashion (P = 0.04).

CONCLUSIONS

Cinnamon supplementation significantly affects obesity measures. It could be recommended as a weight-reducing supplement in obesity management.

Population-representative analysis of dietary supplementation among Americans with diabetes mellitus

BACKGROUND

Few population-representative studies have examined dietary supplement use among Americans with diabetes mellitus (DM). This investigation analyzed dietary supplementation and DM data from the 2013-2014 National Health and Nutrition Examination Survey (NHANES).

METHODS

Data from 5040 adult participants were analyzed, including 639 participants reporting a diagnosis of DM (Method 1), which increased to 1036 after including participants reporting "borderline" DM or prediabetes (Method 2). Participants reported dietary supplements used over the past month. The prevalence of supplementation was compared among participants with and without DM using the Rao-Scott likelihood Chi-squared test; multivariate logistic regression was used to examine whether DM was an independent predictor of supplementation.

RESULTS

Regardless of whether Method 1 or Method 2 was used, dietary supplementation was more prevalent among participants with DM (Method 1, 61.4% vs. 54.4%, P = 0.024; Method 2, 62.7% vs. 53.5%, P < 0.001). After adjusting for a variety of demographic and health-related variables, the presence of DM was no longer associated with supplementation for Method 1 (odds ratio [OR] 1.01; 95% confidence interval [CI] 0.78-1.32; P = 0.925) or Method 2 (OR 1.13; 95% CI 0.91-1.41; P = 0.238). Approximately four of every five products taken for the purpose of managing DM were self-prescribed, the most common being multivitamins-minerals, cinnamon-containing supplements, and chromium-containing supplements.

CONCLUSIONS

Slightly more than six out of 10 Americans with DM use dietary supplements each month and, although this is higher than Americans without DM, it does not appear to be due to DM per se.

Inhibition of α-glucosidase activity by selected edible seaweeds and fucoxanthin

A 5 mg/mL solution of water, methanol and acetone extracts of seaweeds were used for α-glucosidase inhibition assay hyphenated with high performance liquid chromatography-mass spectrometry (HPLC-HRMS). The results showed acetone extracts of Undaria pinnatifida has the strongest inhibitory effect against α-glucosidase activity with IC50 0.08 ± 0.002 mg/mL. The active compound found in Undaria pinnatifida was identified as fucoxanthin. Analytical standard sample of fucoxanthin significantly inhibited α-glucosidase with IC50 value 0.047 ± 0.001 mg/mL. An inhibition kinetics study indicates that fucoxanthin is showing mixed-type inhibition. These results suggest that Undaria pinnatifida has a potential to inhibit α-glucosidase and may be used as a bioactive food ingredient for glycaemic control.

Phytotherapy in the Management of Diabetes: A Review

Phytotherapy has long been a source of medicinal products and over the years there have been many attempts to use herbal medicines for the treatment of diabetes. Several medicinal plants and their preparations have been demonstrated to act at key points of glucidic metabolism. The most common mechanisms of action found include the inhibition of α-glucosidase and of AGE formation, the increase of GLUT-4 and PPARs expression and antioxidant activity. Despite the large amount of literature available, the actual clinical effectiveness of medicinal plants in controlling diabetes-related symptoms remains controversial and there is a crucial need for stronger evidence-based data. In this review, an overview of the medicinal plants, which use in the management of diabetes is supported by authoritative monographs, is provided. References to some species which are currently under increasing clinical investigation are also reported.

Polyphenol-rich curry made with mixed spices and vegetables benefits glucose homeostasis in Chinese males (Polyspice Study): a dose-response randomized controlled crossover trial

PURPOSE

To investigate acute effects of two doses of a polyphenol-rich curry made with seven different spices and four base vegetables, eaten with white rice, on 24 h glucose response, postprandial insulinemia, triglyceridemia and 24 h urinary total polyphenol excretion (TPE).

METHODS

Randomized, controlled, dose-response crossover trial in healthy, Chinese men [n = 20, mean ± standard deviation (SD) age 23.7 ± 2.30 years, BMI 23.0 ± 2.31 kg/m²] who consumed test meals matched for calories, macronutrients and total vegetables content, consisting either Dose 0 Control (D0C) or Dose 1 Curry (D1C) or Dose 2 Curry (D2C) meal. 24 h glucose concentration was measured using continuous glucose monitoring (CGM), together with postprandial plasma insulin and triglyceride for up to 7 h. Total polyphenol content (TPC) of test meals and urinary TPE were measured using the Folin-Ciocalteu assay.

RESULTS

TPC for D0C, D1C and D2C were 130 ± 18, 556 ± 19.7 and 1113 ± 211.6 mg gallic acid equivalent (GAE) per portion served, respectively (p < 0.0001). Compared with D0C meal, we found significant linear dose-response reductions in the 3-h postprandial incremental AUC (iAUC) for CGM glucose of 19% and 32% during D1C and D2C meals respectively (p < 0.05) and non-significant linear dose response reductions in iAUC of insulin (p = 0.089). Notably, we found significant dose-dependent increases in postprandial triglyceride with increasing curry doses (p < 0.01). Significant increases in TPE with increasing curry doses were also observed (p < 0.01).

CONCLUSION

Polyphenol-rich curry intake can improve postprandial glucose homeostasis. The longer term effects remain to be established.

An Overview of Herbal Products and Secondary Metabolites Used for Management of Type Two Diabetes

Diabetes mellitus is a common effect of uncontrolled high blood sugar and it is associated with long-term damage, dysfunction, and failure of various organs. In the adult population, the global prevalence of diabetes has nearly doubled since 1980. Without effective prevention and management programs, the continuing significant rise in diabetes will have grave consequences on the health and lifespan of the world population, and also on the world economy. Supplements can be used to correct nutritional deficiencies or to maintain an adequate intake of certain nutrients. These are often used as treatments for diabetes, sometimes because they have lower costs, or are more accessible or "natural" compared to prescribed medications. Several vitamins, minerals, botanicals, and secondary metabolites have been reported to elicit beneficial effects in hypoglycemic actions in vivo and in vitro; however, the data remain conflicting. Many pharmaceuticals commonly used today are structurally derived from natural compounds from traditional medicinal plants. Botanicals that are most frequently used to help manage blood glucose include: bitter melon (Momordica charantia), fenugreek (Trigonella foenum graecum), gurmar (Gymnema sylvestre), ivy gourd (Coccinia indica), nopal (Opuntia spp.), ginseng, Russian tarragon (Artemisia dracunculus), cinnamon (Cinnamomum cassia), psyllium (Plantago ovata), and garlic (Allium sativum). In majority of the herbal products and secondary metabolites used in treating diabetes, the mechanisms of action involve regulation of insulin signaling pathways, translocation of GLUT-4 receptor and/or activation the PPARγ. Several flavonoids inhibit glucose absorption by inhibiting intestinal α-amylase and α-glucosidase. In-depth studies to validate the efficacies and safeties of extracts of these traditional medicinal plants are needed, and large, well designed, clinical studies need to be carried out before the use of such preparations can be recommended for treatment and/or prevention of diabetes. The main focus of this review is to describe what we know to date of the active compounds in these, along with their glucose-lowering mechanisms, which are either through insulin-mimicking activity or enhanced glucose uptake.

Do Cinnamon Supplements Have a Role in Glycemic Control in Type 2 Diabetes? A Narrative Review

Cinnamon (Cinnamomum sp) has been suggested to help patients with type 2 diabetes mellitus (T2DM) achieve better glycemic control, although conclusions from meta-analyses are mixed. To evaluate whether the use of cinnamon dietary supplements by adults with T2DM had clinically meaningful effects on glycemic control, as measured by changes in fasting plasma glucose (FPG) or hemoglobin A1c (HbA1c), a comprehensive PubMed literature search was performed. Eleven randomized controlled trials were identified that met our inclusion criteria that enrolled 694 adults with T2DM receiving hypoglycemic medications or not. In 10 of the studies, participants continued to take their hypoglycemic medications during the cinnamon intervention period. Studies ranged from 4 to 16 weeks in duration; seven studies were double-blind. Cinnamon doses ranged from 120 to 6,000 mg/day. The species of cinnamon used varied: seven used Cinnamomum cassia or Cinnamomum aromaticum, one used Cinnamomum zeylanicum, and three did not disclose the species. Because of the heterogeneity of the studies, a meta-analysis was not conducted. All 11 of the studies reported some reductions in FPG during the cinnamon intervention, and of the studies measuring HbA1c very modest decreases were also apparent with cinnamon, whereas changes in the placebo groups were minimal. However, only four studies achieved the American Diabetes Association treatment goals (FPG <7.2 mmol/L [130 mg/dL] and/or HbAlc <7.0). We conclude that cinnamon supplements added to standard hypoglycemic medications and other lifestyle therapies had modest effects on FPG and HbA1c. Until larger and more rigorous studies are available, registered dietitian nutritionists and other health care professionals should recommend that patients continue to follow existing recommendations of authoritative bodies for diet, lifestyle changes, and hypoglycemic drugs.

The effect of Cinnamomum zeylanicum bark water extract on memory performance in alloxan-induced diabetic mice

Cinnamomum zeylanicum (cinnamon) has a wide range of beneficial effects including mild glucose lowering activity. The aim of the present study was to investigate whether cinnamon bark extract has the potential to improve memory performance and glucose profiles in diabetic mice. Memory was assessed by the novel object recognition task in male Balb/c mice. In this method, the difference between exploration time of a familiar object and a novel object was considered as an index of memory performance (recognition index, RI). The water extract was prepared by boiling cinnamon bark for 15 min. Alloxan induced diabetes in animals (serum glucose levels were 322 ± 7.5 mg/dL), and also impaired memory performance (RI= -3.3% ± 3.3) which differed significantly from control animals (RI = 32% ± 6.5). Although treatment with cinnamon only reduced fasting blood glucose level moderately but it improved memory performance remarkably (RI = 25.5% ± 5.6). Oxidative stress following administration of cinnamon extract was lower in diabetic mice. It was concluded that cinnamon water extract could be a useful alternative medicine in diabetic patients’ daily regimen which not only reduces blood glucose levels but also improves memory performance and lipid peroxidation level.

Dietary polyphenols are inversely associated with metabolic syndrome in Polish adults of the HAPIEE study

Purpose

The aim of this study was to evaluate the association between total and individual classes and subclasses of dietary polyphenol intake and prevalence of metabolic syndrome (MetS) in the Polish arm of the Health, Alcohol and Psychosocial factors In Eastern Europe cohort study.

Methods

A cross-sectional population-based survey including 8821 adults (51.4 % female) was conducted in Kraków, Poland. Dietary polyphenol intake was evaluated using food frequency questionnaires and matching food consumption data with the Phenol-Explorer database. MetS was defined according to the International Diabetes Federation definition. Linear and logistic regression models were performed to estimate odds ratios (ORs) and confidence intervals (CIs).

Results

Significant differences in age and energy intake among different categories of total dietary polyphenol intake were found. Body mass index (BMI), waist circumference (WC), blood pressure, and triglycerides were significantly lower among individuals in the higher quartiles of polyphenol intake, but a linear association was found only for BMI and WC. After adjusting for potential confounding factors, individuals in the highest quartile of polyphenol intake were less likely to have MetS (OR 0.80; 95 % CI 0.64, 0.98 and OR 0.70; 95 % CI 0.56, 0.86 for both men and women, respectively). High total polyphenol intake was negatively associated with WC, blood pressure, high lipoprotein cholesterol, and triglycerides in women, and fasting plasma glucose in both genders. Among individual classes of polyphenols, phenolic acids and stilbenes were significantly associated with MetS; lignans and stilbenes with WC; phenolic acids with blood pressure and triglycerides; and flavonoids with fasting plasma glucose. Among specific subclasses of polyphenols, hydroxycinnamic acids, flavanols, and dihydrochalcones had the most relevant role.

Conclusions

Total and individual classes and subclasses of dietary polyphenols were inversely associated with MetS and some of its components.

Electronic supplementary material

The online version of this article (doi:10.1007/s00394-016-1187-z) contains supplementary material, which is available to authorized users.