The Effect of Walnut () Leaf Extract on Glycemic Control and Lipid Profile in Patients With Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.

Atieh Mirzababaei, Mojtaba Daneshvar, Faezeh Abaj, Elnaz Daneshzad, Dorsa Hosseininasab, Cain C T Clark, Khadijeh Mirzaei

Journal: Clinical nutrition research 2022;11(2):120-132

PMID: 35558998

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Plain Language Summary

The main characteristics of type 2 diabetes mellitus (T2DM) are hyperinsulinemia, insulin resistance, and β-cells decline, concomitant to dyslipidaemia. The latter includes abnormalities in concentrations of triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), or total cholesterol (TC), which are major risk factors for cardiovascular diseases. The aim of this study was to evaluate the effect of Juglans regia leaf extract (JRLE) on glycaemic control and lipid profile in T2DM patients. This study is a systematic review and meta-analysis of four randomised controlled studies. All studies were conducted in Iran, on T2DM patients, and both genders. Results show that JRLE supplementation did not have any significant effect on TC, LDL-C, and HDL-C; however, it significantly reduced fasting blood glucose and significantly increased alanine transaminase [enzyme]. Authors conclude that their findings strengthen the available evidence of JRLE as an alternative adjunctive therapy to better control glycaemic targets and lipid parameters.

Abstract

Numerous clinical trials have examined the beneficial effects of leaf extract (JRLE) in patients with type 2 diabetes mellitus (T2DM); however, the results of these studies are inconsistent. Therefore, we conducted the current systematic review and meta-analysis to evaluate the effect of JRLE on glycemic control and lipid profile in T2DM patients. We searched online databases including PubMed, Scopus, EMBASE, and Web of Science for randomized controlled clinical trials that examined the effect of JRLE on glycemic and lipid indices in T2DM patients. Data were pooled using both fixed and random-effect models and weighted mean difference (WMD) was considered as the overall effect size. Of the total records, 4 eligible studies, with a total sample size of 195 subjects, were included. The meta-analysis revealed that JRLE supplementation significantly reduces fasting blood glucose (WMD, -18.04; 95% confidence interval [CI], -32.88 mg/dL, -3.21 mg/dL; p = 0.017) and significantly increases fasting insulin level (WMD, 1.93; 95% CI, 0.40 U/L, 3.45 U/L; p = 0.014). Although the overall effect of JRLE supplementation on hemoglobin A1c was not significant, a significant reduction was seen in studies with an intervention duration of > 8 weeks (WMD, -0.64; 95% CI, -1.16%, -0.11%; p = 0.018). Moreover, we also found no significant change in lipid parameters. Our findings revealed a beneficial effect of JRLE supplementation on glycemic indices in T2DM patients, but no significant improvement was found for lipid profile parameters.

Address: Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran 14155-6117, Iran.; Non-Communicable Diseases Research Center, Alborz University of Medical Sciences, Karaj 3149779453, Iran.; Department of Nutrition, Science and Research Branch, Islamic Azad University, Tehran 1468763785, Iran.; Centre for Intelligent Healthcare, Coventry University, Coventry CV1 5FB, UK.

DOI: 10.7762/cnr.2022.11.2.120