Research Article: The Effect of Dried Glycyrrhiza Glabra L. Extract on Obesity Management with Regard to PPAR-γ2 (Pro12Ala) Gene Polymorphism in Obese Subjects Following an Energy Restricted Diet

Date Published: June 30, 2017

Publisher: Tabriz University of Medical Sciences

Author(s): Nazli Namazi, Mohammad Alizadeh, Elham Mirtaheri, Safar Farajnia.


Purpose: Obesity is a multi-factorial health problem which results from the interaction of environmental and genetic factors. The aim of the present study was to determine the effects of dried licorice extract with a calorie restricted diet on anthropometric indices and insulin resistance with nutrigenetic approach.

Partial Text

Glycyrrhiza glabra L. (Fabaceae) generally which known as Licorice is a medicinal herb that widely grows in Mediterranean region and the south-west Asia. It contains various components with pharmacological properties including glabridin, glycyrrhizin, beta-Glycyhrritinic acid, flavonoids, sterols, amino acids, chalcones, isoflavones and triterpenoidsaponins.1,2 Licorice root frequently used in traditional medicine particularly for gastric and duodenal ulcers, helicobacter pylori effects and allergenic reactions. Previous studies have reported antioxidant, anti-mutagenic, anti-inflammatory, anti-viral, anti-bacterial and anti-asthmatic properties for licorice and its components.1,3 Additionally in the resent years, the anti-obesity effects of Licorice and its effective ingredients have been reported.4-9

A total of 216 obese subjects were screened for the PPARγ (Pro12Ala) gene polymorphism. The prevalence rates were 74.1% (n=160) for Pro/Pro and 25.9% (n=56) for Pro/Ala. Moreover, no participants had the Ala/Ala genotype. Throughout the trial, three subjects in the Licorice group were excluded, because of gastric complications (n=2) and not adhering to the study procedure (n=1). In the placebo group, two subjects were also excluded due to not adhering to the study procedure and gastrointestinal disorder (Figure 1). Finally 67 subjects completed the study. The capsule counts indicated that all the participants who completed the study had high compliance (>90%) with the supplementation.

Our findings indicated that independent of the licorice supplementation, body weight, BMI, WC and WHR decreased and QUICKI increased in obese subjects with regard to the Pro12Ala polymorphism of PPAR-γ2 gene. In subjects with Pro/Pro genotype, more changes were observed at the end of the study. Furthermore, no interactions between gene and interventions were found.

In Iranian obese subjects, it seems the Pro/Pro polymorphism of the PPAR-γ2 gene induce favourable effects on obesity management and insulin sensitivity. Furthermore, our findings did not support greater benefits for licorice supplementation vs. a low-calorie diet alone. Further clinical trials are needed to clarify whether PPAR-γ2 polymorphism or other obesity gene polymorphism can affect responses to obesity treatment.

We are grateful to the participants for their cooperation. The authors also would like to thank Drug Applied Research Center, Tabriz University of Medical Sciences for funding of the project.

The present study was approved by the Ethical Committee of Tabriz University of Medical Sciences and it was registered on the Iranian Registry of Clinical Trials (IRCT registration number: IRCT2013062811288N3).

The authors declare no conflict of interests.




Leave a Reply

Your email address will not be published.