Effects of <i>Melissa officinalis</i> L. (Lemon Balm) Extract Supplementation on Cardiovascular Risk Factors: A Pooled Analysis of Randomized Controlled Trials

Several clinical trials have investigated the effects of Melissa officinalis (lemon balm) on cardiovascular risk factors, but have yielded conflicting results and had only modest sample sizes. The aim of this pool analysis was to summarize the evidence of the effects of Melissa officinalis supplementation on plasma lipid profiles, body weight, blood pressure and glucose levels. Original randomized controlled trials (RCTs) that assessed the clinical effects of Melissa officinalis consumption in human participants and published before June 2020 were identified by searching online databases, including PubMed, Scopus, Web of Science and Google Scholar databases. The quality of trials was assessed using the Cochrane Risk of Bias Tool. Quantitative data analysis was performed using weighed mean difference (WMD) and 95% confidence interval (CI) as summary statistics. Standard methods for assessing statistical heterogeneity and publication bias were used, respectively. Four trials with 244 participants were included in the final analysis. Pooling of results showed that Melissa officinalis significantly lowered total cholesterol (TC) (WMD, -7.55 mg/dL; 95% CI -14.99, -0.12; P=0.045), low-density lipoprotein cholesterol (LDL-C) (WMD, -11.33 mg/dL; 95% CI -19.46, -3.21; P=0.006), glycated hemoglobin (HbA1c) (WMD, -0.35 %; 95% CI -0.64, -0.07; P=0.01), and Systolic blood pressure (SBP) (WMD, -0.89 mmHg; 95% CI-1.69, -0.09; P=0.03). The use of Melissa officinalis did not appear to significantly alter any other study endpoints. The present findings showed that supplementation with Melissa officinalis extract were associated with a significant reduction in TC, LDL-C, HbA1c, and SBP in humans.