Effect of ginger (Zingiber officinale Roscoe) supplementation on nutritional status and circulating level of some adipocytokines in obese women with regard to genetic polymorphism of leptin, adiponectin, UCP-1 and beta 3 adrenergic receptors

Abstract

Background and Objectives: Currently, the epidemic of obesity has become a major public health issue over the world. Obesity is a multi-factorial disease influenced by the interactions of genetic, environmental and behavioral factors. To date, several strategies have been investigated to manage this disease, particularly the use of medicinal plants as a possible effective way for weight loss and also correction of metabolic disturbances and the pro-inflammatory status along with obesity. Ginger (Zingiber officinale Roscoe) is one of the most widely used medicinal plants around the world. The anti-obesity effect of ginger and its compounds has been recently noticed in experimental studies, however, scientific research in humans is very limited. Moreover its efficacy with considering individuals’ genetic differences has not been ever studied. Accordingly, the present study aimed to investigate the effect of ginger supplementation on nutritional status and circulating levels of some adipocytokines in obese women with nutrigenetics approach, considering the polymorphism of leptin, adiponectin, UCP-1 and ß3ADR genes. Method and Material: In the present randomized double blind placebo controlled study, 80 eligible obese women (30≤BMI˂40) aged 18-45 yr. were randomly assigned to either ginger or placebo groups (receiving 2 g/day of ginger powder or corn starch as two 1g tablets) for 12 weeks. Subjects were tested for changes in body weight, body mass index, waist and hip circumferences, body composition (using an 8-electrode bioelectrical impedance analyzer) and appetite score (using a five items questionnaire) at baseline and every 4 weeks. Dietary intake assessment was also performed using 3-days food record at baseline, weeks 6 and 12. Moreover, fasting blood samples were obtained from all subjects at the beginning and end of intervention to determine serum levels of leptin, resistin, total adiponectin, total antioxidant capacity and malondialdehyde. Genomic DNA was isolated from whole blood samples using the conventional phenol chloroform extraction method and the single-nucleotide polymorphisms of leptin, adiponectin, UCP-1 and ß3ADR genes were genotyped by polymerase chain reaction– restriction fragment length polymorphism (PCR-RFLP) method. Data were analyzed using SPSS software, version 21.0. Results: Ginger consumption for 12 weeks significantly decreased anthropometric parameters, compared to their baseline value and also placebo group (P <0.05), whereas there was no significant difference in changes of body composition. At the end of intervention, significant reductions of total appetite score and dietary intake were observed in both groups. However, these reductions were more pronounced in the ginger group. Ginger vs. placebo consumption was also significantly decreased the total appetite score during 8 weeks of intervention (p=0.009, p=0.028). Moreover significant reductions of serum leptin, resistin and212 Abstract non-significant increase of adiponectin were observed in both groups, especially in ginger group without any significant difference between groups. Besides, the concentration of MDA increased in ginger group (p=0.005) and TAC decreased in placebo group (p=0.029) as compared to the baseline without any significant difference between groups. In our study population (n=70), genotype frequencies of GG, GA and AA for leptin polymorphism G-2548A was 20/0%, 51/4% and 28/6% respectively. The genotype frequencies of TT, TG and GG for adiponectin polymorphism +45 T>G was 67/1%, 27/1% and 5/7% respectively. The genotype frequencies of AA, AG and GG for UCP-1 polymorphism A-3826G was 48/6%, 32/9% and 18/6% respectively. The genotype frequencies of Trp64Trp, Trp64Arg and Arg64Arg for ß3ADR gene was 84/3%, 15/7% and 0% respectively. Furthermore, comparing two study groups with considering subjects' genotypes revealed that decrease of anthropometric parameters (except WHR) by ginger supplement versus placebo were more noticeable in subjects with TT genotype (adiponectin +45 T>G), AA genotype (UCP1 -3826A>G) and Trp64Trp genotype (β3ADR Trp64Arg), rather than other genotypes of each gene. Ginger supplement compared to placebo also resulted in significant decrease of waist and hip circumference in GA genotype (leptin G-2548A). However, its effects on serum leptin and adiponectin, didn’t affected by their polymorphisms (p> 0.05). Conclusion: Our findings demonstrate minor beneficial effects of ginger supplementation on weight loss and some other parameters, which may be affected by subjects’ genotype. However, given the lack of data in this area, ongoing clinical trials are needed.