Plain language summary
Non-alcoholic fatty liver disease (NAFLD) is known to be the most prevalent hepatic disorder that is characterised by the accumulation of lipids within the hepatocytes exceeding 5% of the liver weight in the absence of excessive alcohol intake and secondary causes of liver diseases. Currently, the primary treatment for NAFLD is weight loss by lifestyle therapy involving diet and exercise. The aim of this study was to summarise the available evidence of randomised controlled trials to establish the effect of cinnamon supplementation on changes in liver enzymes among adults. This study is a meta-analysis of seven randomised controlled trials with nine treatment arms. In total, 266 participants were enrolled in selected articles, of which 133 individuals allocated to cinnamon supplementation group and 133 subjects to the control group. Results show that cinnamon cannot effectively reduce the liver enzymes - aspartate aminotransferase, alanine aminotransferase (ALT) and alkaline phosphatase levels. However, subgroup analyses showed that the effect of cinnamon supplementation on ALT levels was significant at dosages of <1500 mg/day, in trials lasting >12 weeks and in trials conducted of both genders. Authors conclude that due to limited availability of studies with NAFLD participants and relatively small sample sizes, well designed trials with adequate sample sizes aimed at NAFLD patients are recommended.
Abstract
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.
Methodological quality
Jadad score
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Allocation concealment
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