A Critical Review of the Hypoglycemic, Hypolipidemic and Anti-inflammatory Effects of Cinnamon in Pa

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Cinnamon is an aromatic spice acquired from the barks present in trees belonging to the Cinnamomum genus, and is a popular flavor additive incorporated in recipes across various cultures and communities. Recent evidence indicates that cinnamon may possess hypoglycemic, antioxidant and anti-inflammatory functions, and thus, may demonstrate as a natural anti-diabetic agent with significant efficiency and potency for both type 2 and type 1 diabetic patients (Van Hul et al., 2017).

 The randomized controlled trial by Ranasinghe et al., (2017), examined the potential impact of Sri Lankan cinnamon (Cinnamomum zeylanicum) as a medicinal agent with anti-diabetic properties (outcomes: insulin, fasting blood glucose, glycosylated hemoglobin, body mass index, blood cholesterol blood pressure,) for type 2 diabetic patients.

The experiment by Shen et al., (2014) aimed to examine the impact of cinnamon extract in enhancing the translocation of glucose transporter 4 across adipose and muscular tissues specifically in type 1 diabetes mellitus.

The randomized controlled trial by Zare et al., (2019), evaluated the impact of cinnamon bark power intake in body mass index, visceral fat, total fat, insulin resistance, fasting levels of insulin, blood lipid, blood cholesterol and blood glucose across type 2 diabetics.

The randomized controlled trial by Talaei et al., (2017), evaluated the impact of cinnamon extract intake on blood glycemic outcomes, antioxidant status and advanced glycemic end products in type 2 diabetics.

Thus, based on the given papers, the primary objective is to critically review current evidence based research on the impact and efficiency of cinnamon in regulating inflammatory, blood glucose, blood lipid and antioxidant outcomes associated in both type 1 and type 2 diabetes mellitus patients.

Diabetes Mellitus (DM) is a metabolic, chronic disorder associated with impairments in the amount or the potency of the hormone insulin being secreted by the pancreas (Brochot et al., 2017). As per the World Health Organization (WHO, 2018), DM was prevalent across approximately 422 million of the global population in the year 2014, while approximately 1.6 million individuals globally were reported to succumb to their injuries as a result of the same, in the year 2016. The American Diabetes Association (ADA, 2017) also reported the prevalence of DM in approximately 9.4% of the American population during the year 2015.

Statement of Purpose/Objective

If not controlled in a timely manner, DM is likely to pave the way for increased risk of long term metabolic conditions such as obesity, cancer, renal disorders and fatal cardiovascular conditions, which in turn, exerts financial complications for both the individual, the community as well as the nation. Thus, with respect to the same, the issue of DM needs immediate mitigation by healthcare organizations across national as well as international levels (Costello et al., 2017).

Prolonged consumption of a nutritionally imbalanced diet, rich in sugars, refined carbohydrates and saturated fats, has been evidenced to be one of the major facilitators of the metabolic pathology of DM. Such pathologies may be prolonged with respect to socioeconomically underprivileged communities (such as ethnic minorities, populations living in poverty or across remote locations) due to their tendency to purchase and consume inexpensive, easily available fast and processed foods rich in sugars and saturated fats (Meeks et al., 2016). Additionally, as discussed earlier, DM and its multiple metabolic comorbidities often compel an individual to incur considerable medical cost which in turn, is likely to negatively impact the affordability and accessibility of healthcare services across socioeconomically underprivileged communities. There is thus a need to research extensively on novel and novel diabetic treatments which are not just clinical effective but also financial feasible for the purpose of ensuring the achievement of long term health outcomes across such communities (Creamer et al., 2016). Indeed, as per the Centers of Disease Control and Prevention (CDC, 2017), DM has been reported to demonstrate one of the highest prevalence rates across ethnic minority communities such as Alaskan Natives (15.1%), Hispanics (12.1%) as well as Blacks (12.7%) and has been evidenced to be associated with approximately $237 million of direct national clinical costs.

Cinnamon, an aromatic and earthy bark procured from the trees of the Cinnamomum genus, have been evidenced to be used since traditional times, as a naturally potent solution for the management of diabetic symptoms as well as for the mitigation of inflammatory and hyperlipidemia associated health outcomes.  While several qualitative studies have reported the anti-diabetic benefits of cinnamon, there is a dearth of quantitative studies providing an in-depth analysis of the anti-hyperglycemic, anti-inflammatory and anti-hyperlipidemic impacts of the same. Similarly, there is a need for further exploratory and analytical research on the acclaimed weight loss and slimming effects of cinnamon across diabetic patients specifically (Azimi et al., 2016).

Part 2

Thus, based on the above, the purpose is to critically review current evidence based research on the mechanisms underlying the hypoglycemic, hypolipidemic and anti-inflammatory effects of cinnamon across diabetic patients, as well as the prevalence of any adverse impacts if any.  

A total of four scholarly papers have been reviewed for the same: the randomized controlled trial by Ranasinghe et al., (2017), the animal study by Shen et al., (2014), randomized controlled trial by Zare et al., (2019) and the randomized controlled trial by Talaei et al., (2017). These have been critically reviewed and expounded upon in the succeeding sections of this paper as follows:

The randomized controlled trial design by Ranasinghe et al., (2017), aimed to examine the potential impact of Sri Lankan cinnamon (Cinnamomum zeylanicum) as a medicinal agent with anti-diabetic properties (outcomes: insulin, fasting blood glucose, glycosylated hemoglobin, body mass index, blood cholesterol blood pressure,) for type 2 diabetic patients. As per the randomized controlled trial (RCT) design by Ranasinghe et al., (2017), the authors predicted outcomes such as cinnamon’s function as a blood sugar lowering effect is largely due to the presence of ‘coumarins’ – biologically potent ingredients which have been in turn, evidenced to improve the intake of glucose via the activation of the activity of insulin receptor kinase, automatic stimulation of insulin receptor phosphorylation and enhancement of the activity of glycogen synthase. In criticism, however, the RCT by Talaei et al., (2017) did not observe any significant insulin-stimulating impact of 3 grams of cinnamon powder, possible due to the short, eight week period of the study across a relatively small sample size of 44 diabetic patients. The role of study duration can further be largely observed in the RCT by Zare et al., (2019) which observed the positive association between cinnamon and the expression of carbohydrate and lipid metabolism-associated UCP3 gene after observing significant effects of powdered cinnamon bark in the form of 500 mg capsules upon reduction of insulin resistance and fasting insulin outcomes for a period of 3 months on 140 adult patients with type 2 diabetes mellitus. Interestingly, a different hypoglycemic mechanism of action was examined as per the animal experiment by Shen et al., (2014), in comparison to other studies in which 30 µg/ml extracts of cinnamon have the potential to exert anti-diabetic effects due to their observed ability to enhance the uptake of glucose via active translocation of GLUT4 across the cellular membranes to the adipocytes and muscular tissues of rats. Thus, the above findings demonstrate mixed results with respect to the hypoglycemic mechanisms of different forms of cinnamon.

Issue

The RCT by Zare et al., (2019), was the only research out of the four studies which extensively analyzed the impact of cinnamon on the blood lipid outcomes and overall anthropometric measurements across diabetic patients. The administration of 1 gram of powdered bark of cinnamon was associated with significant reductions in blood lipid outcomes of LDL cholesterol (-5.7 ± 2.6 mg/dl), total cholesterol (-16.2 ± 2.9 mg/dl), triglycerides (- 6.2 ± 4.0 mg/dl) as well as observed reductions in the overall body mass index (- 0.63 ± 0.06 kg/m²), visceral (-0.69 ± 0.13 %) and body fat (-1.92 ± 0.26 %) outcomes across diabetic patients for a period of 3 months (p < 0.001). Such weight and lipid regulatory mechanism by cinnamon have been evidenced to be caused due its facilitation of UCP3 genetic expression which in turn, paves the way for improved oxidation of fatty acids and overall metabolic rates.

Cinnamon has been evidenced to induce reductions in levels of oxidative stress via regulation in the formation of harmful inflammatory substances like advanced glycation end products within the body (Whitfield et al., 2016). In criticism however, conflicting results were reported by Talaei et al., (2017), where no significant changes were observed with respect to the reduction of total capacity of antioxidants, carboxymethyl lysine and malonialdehyde upon cinnamon supplementation for 8 weeks across type 2 diabetics. Such observations thus demonstrate the prevalence of conflicting results and the need for further scientific exploration.

According to the RCT proposal by Ranasinghe et al., (2017), prolonged consumption of cinnamon and thus, coumarins, are likely to exacerbate the latter’s anti-coagulation functions which in turn, have been evidenced to cause fatal hepatic damage. In criticism however, no such serious consequences were demonstrated in the 3 month RCT by Zare et al., (2019), except for incidence of allergic reaction across one participant.

Recommendations and Conclusion

From the above critical examination of the findings, it can be observed that despite possessing a comprehensive set of findings, each study comprises of a range of strengths and limitations. While the trial design by Ranasinghe et al., (2017) provides a promising approach in terms of evaluating the anti-diabetic effects of relatively unexplored Sri Lankan cinnamon, the fact that the same is a proposal and not a fully completed study is a major limitation. Alternatively, the experiment by Shen et al., (2014) provides comprehensive, in-depth findings on the true biochemical mechanisms of cinnamon. However, considering that the research comprised of animals raises doubts on the overall applicability of obtained results (Cor, 2016). Likewise, issues of applicability and validity are also prevalent with respect to the findings by Talei et al., (2017), due to its small sample size and relatively short duration of research, despite presenting an alternative critical insight into obtained findings. The RCT by Zare et al., (2019), can be considered to present highly valid and applicable findings considering it large follow up period and sample size as well as comprehensive exploration of the claimed anthropometric, hypoglycemic and hypolipidemic outcomes of cinnamon. However, the study’s inclusion of participants with both obesity and DM raises issues with respect to applicability of findings across only obese or only diabetic individuals (Cor, 2016).  

Background

Thus, from the above literature review, it can be concluded that the question concerning the evidenced nutritional benefits of cinnamon were indeed answered with respect to its anti-inflammatory, anti-diabetic and anti-hyperlipidemia outcomes. However, as observed from the above literature review, differences were observed with respect to the amount of cinnamon added and the duration of study which in turn contribute to varied, conflicting and overall inconclusive findings. Thus, to conclude, considering the conflicting methodologies and nature of findings, further comprehensive research with larger sample sizes and follow up periods are required prior to practically translating these findings into real life scenarios, especially in terms of establishing standard amounts and forms of cinnamon to be administered to reap tis benefits.

References

ADA. (2017). Statistics About Diabetes | ADA. Retrieved 15 February 2020, from https://www.diabetes.org/resources/statistics/statistics-about-diabetes.

Azimi, P., Ghiasvand, R., Feizi, A., Hosseinzadeh, J., Bahreynian, M., Hariri, M., & Khosravi-Boroujeni, H. (2016). Effect of cinnamon, cardamom, saffron and ginger consumption on blood pressure and a marker of endothelial function in patients with type 2 diabetes mellitus: A randomized controlled clinical trial. Blood pressure, 25(3), 133-140.

Brochot, A., Gérard, P., Bäckhed, F., & Cani, P. D. (2017). Reduced obesity, diabetes and steatosis upon cinnamon and grape pomace 1 are associated with changes in gut microbiota and markers of gut barrier 2.

(2017). Diabetes Statistic Report. Retrieved 15 February 2020, from https://www.cdc.gov/features/diabetes-statistic-report/index.html.

Cor, M. K. (2016). Trust me, it is valid: Research validity in pharmacy education research. Currents in Pharmacy Teaching and Learning, 8(3), 391-400.

Costello, R. B., Dwyer, J. T., Saldanha, L., Bailey, R. L., Merkel, J., & Wambogo, E. (2016). Do cinnamon supplements have a role in glycemic control in type 2 diabetes? A narrative review. Journal of the Academy of Nutrition and Dietetics, 116(11), 1794-1802.

Creamer, J., Attridge, M., Ramsden, M., Cannings‐John, R., & Hawthorne, K. (2016). Culturally appropriate health education for Type 2 diabetes in ethnic minority groups: an updated Cochrane Review of randomized controlled trials. Diabetic Medicine, 33(2), 169-183.

Meeks, K. A., Freitas-Da-Silva, D., Adeyemo, A., Beune, E. J., Modesti, P. A., Stronks, K., ... & Agyemang, C. (2016). Disparities in type 2 diabetes prevalence among ethnic minority groups resident in Europe: a systematic review and meta-analysis. Internal and emergency medicine, 11(3), 327-340.

Ranasinghe, P., Galappaththy, P., Constantine, G. R., Jayawardena, R., Weeratunga, H. D., Premakumara, S., & Katulanda, P. (2017). Cinnamomum zeylanicum (Ceylon cinnamon) as a potential pharmaceutical agent for type-2 diabetes mellitus: study protocol for a randomized controlled trial. Trials, 18(1), 446.

Shen, Y., Honma, N., Kobayashi, K., Jia, L. N., Hosono, T., Shindo, K., ... & Seki, T. (2014). Cinnamon extract enhances glucose uptake in 3T3-L1 adipocytes and C2C12 myocytes by inducing LKB1-AMP-activated protein kinase signaling. PLoS One, 9(2).

Talaei, B., Amouzegar, A., Sahranavard, S., Hedayati, M., Mirmiran, P., & Azizi, F. (2017). Effects of cinnamon consumption on glycemic indicators, advanced glycation end products, and antioxidant status in type 2 diabetic patients. Nutrients, 9(9), 991.

Van Hul, M., Geurts, L., Plovier, H., Druart, C., Everard, A., Ståhlman, M., ... & Maguin, E. (2017). Reduced obesity, diabetes and steatosis upon cinnamon and grape pomace are associated with changes in gut microbiota and markers of gut barrier. American Journal of Physiology-Endocrinology and Metabolism.

Whitfield, P., Parry-Strong, A., Walsh, E., Weatherall, M., & Krebs, J. D. (2016). The effect of a cinnamon-, chromium-and magnesium-formulated honey on glycaemic control, weight loss and lipid parameters in type 2 diabetes: an open-label cross-over randomised controlled trial. European journal of nutrition, 55(3), 1123-1131.

WHO. (2018). Diabetes. Retrieved 15 February 2020, from https://www.who.int/news-room/fact-sheets/detail/diabetes.

Zare, R., Nadjarzadeh, A., Zarshenas, M. M., Shams, M., & Heydari, M. (2019). Efficacy of cinnamon in patients with type II diabetes mellitus: A randomized controlled clinical trial. Clinical Nutrition, 38(2), 549-556.