Cinnamon had been studied in-vitro for its beneficial effects on blood glucose and insulin resistance although its human studies have been contradictory.
Hence, researchers sought to evaluate the effect of cinnamon supplementation on NF-kB, SIRT1 and systemic inflammation factors (hs-CRP, IL-6 and TNF-α) levels among type 2 diabetes patients.
Biomarkers like high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), and tumour necrosis factor alpha (TNF-α) have been used to predict the onset and development of diabetes in pre-diabetic and diabetic patients
Sirtuin-1 (SIRT1) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) play a role in the incidence of diabetes-related complications.
The study was published in Nutrition journal.
The randomised double-blind controlled clinical trial recruited 44 diabetic adults (25 to 70 years) in Iran. The volunteers were newly diagnosed type 2 diabetics or had a history of less than eight years, and took metformin as medication.
The volunteers were divided into two equal groups, study and control.
The study group were told to take three capsules of 1g cinnamon extract after each main meal daily for eight weeks. The placebo group took microcrystalline cellulose.
Blood samples were taken after 12 hours of overnight fasting at the beginning and end of intervention period. Plasma concentrations of SIRT1, NF-kB, hs-CRP, IL-6 and TNF-α were analysed.
No remarkable findings
After eight weeks, there were no significant difference of TNF-α, IL-6, and hs-CRP in both study and placebo groups.
According to the researchers, type 2 diabetes is associated with increasing NF-kB activity. NF-kB is a protein responsible for cytokine production and is vital for maintaining the body's immune defense system and ability to combat disease.
In the present study, they found that NF-kB levels were not significantly different in the study group (p=0.69) after eight weeks. The placebo group also did not see any significant difference (p=0.055).
For SIRT1, no significant reduction was seen in both the study (p=0.39) and placebo group (p=0.38), at baseline (p=0.13) and after eight weeks (p=0.51).
Cinnamon and systemic inflammation factors
The findings showed that 3g of cinnamon supplementation daily for eight weeks had no beneficial impacts on plasma levels of NF-kB, SIRT1 and systemic inflammation factors including hs-CRP, IL-6 and TNF-α in type 2 diabetic patients after eight weeks of intervention.
Some studies have indicated that cinnamon contains anti-inflammatory ingredients such as cinnamaldehyde, eugenol, and terpene to reduce mild systemic inflammation (hs-CRP, IL-6, and TNF-α).
Researchers said: “Up to date, no similar study has been performed regard to cinnamon supplementation effects on NF-kB and SIRT1 in type 2 diabetes patients to compare with our results.”
They also reported no human studies have investigated the pharmacodynamic effects of metformin and cinnamon.
Animal studies have found that high dose of cinnamon (600 mg/Kg/day) given to diabetic rates can increase the effectiveness of metformin. In contrast, no effect was seen in lower dose (300 mg/kg/day). The present study used 3000 mg/day cinnamon in humans.
Researchers suggested further high-dose cinnamon research are required to identify the true pharmacological effects between metformin and cinnamon.
Recommendations for future studies
The study reported that cinnamon supplementation of 3g per day for eight weeks does not have any remarkable effect in the reduction of NF-kB, SIRT1, hs-CRP, IL-6 and TNF-α plasma levels which play a key role in atherogenicity in type 2 diabetes patients.
The researchers also explained they faced limitations such as financial constraint and low cooperation of participants and hence could not extend the intervention duration and increase cinnamon dosage.
As their findings were not statistically significant, researchers said: “Before our findings can be extended to the general and diabetic populations, more investigations and longer intervention duration could be trialed. Further investigations on diabetic patients with common complications such as neuropathy, nephropathy and retinopathy are needed to fully elucidate the effects of cinnamon extract on plasma levels of inflammatory markers.”
Source: Nutrition journal
“Effects of cinnamon supplementation on expression of systemic inflammation factors, NF-kB and Sirtuin-1 (SIRT1) in type 2 diabetes: a randomized, double blind, and controlled clinical trial”
Authors: Mina Davari, et al.