A Plant Extract Derived from Lemon Myrtle Leaves: Clinical Trials and Mechanistic Studies on Improving Human GLP-1 Levels, Controlling Blood Glucose, and Reducing Body Weight

Abstract

The increasing prevalence of obesity and type 2 diabetes has highlighted the urgent need for effective and natural therapeutic interventions. Backhousia citriodora (Lemon myrtle), an Australian native plant, is traditionally recognized for its antimicrobial and anti-inflammatory properties; however, its role in metabolic regulation remains underexplored. This study aimed to investigate the effects of Lemon myrtle leaf extract on human glucagon-like peptide-1 (GLP-1) levels, blood glucose control, and body weight regulation through a combination of clinical trials and mechanistic studies. A double-blind, randomized, placebo-controlled clinical trial was conducted on individuals with impaired glucose metabolism, where participants received either Lemon myrtle leaf extract or a placebo for 12 weeks. Key metabolic parameters, including fasting glucose, insulin levels, and GLP-1 secretion, were measured before and after the intervention. The results demonstrated a significant increase in circulating GLP-1 levels in the Lemon myrtle leaf extract group compared to the placebo (p < 0.05), along with improved fasting blood glucose and postprandial glucose response. Furthermore, a moderate yet significant reduction in body weight was observed among participants receiving Lemon myrtle leaf extract, suggesting potential benefits for weight management. Mechanistic studies revealed that flavonoids compounds in Lemon myrtle leaf extract could enhance GLP-1 secretion by stimulating gut enteroendocrine cells and inhibiting dipeptidyl peptidase-4 (DPP-4), thereby prolonging GLP-1 activity and improving glucose homeostasis. These findings suggest that Lemon myrtle leaf extract may serve as a promising natural intervention for metabolic disorders by modulating GLP-1 pathways, regulating blood glucose, and promoting weight loss. Further large-scale trials and mechanistic explorations are necessary to validate these benefits and assess its potential application in dietary and pharmaceutical formulations.