Grape Seed Extract Supplementation and the Effects on the Biomarkers of Oxidative Stress and Metabolic Profiles in Female Volleyball Players: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial
Authors: Mohsen Taghizadeh
Mohammad Reza Memarzadeh
Zatollah Asemi
Elaheh Malekian
Ali Akbar Mohammadi
Journal: Iranian Red Crescent Medical Journal (2016)
Discipline: CLINICAL MEDICINE
Keywords: Athletes; Grape Seed Extract; Oxidative Stress.
Affiliations: Research Center for Biochemistry and Nutrition in Metabolic Diseases, Kashan University of Medical Sciences, Kashan, IR Iran., Barij Medicinal Plants Research Center, Kashan, IR Iran.

Abstract:  Background: Only limited data are available for evaluating the effects of the administration of grape seed extract (GSE) on the metabolic status of female volleyball players. Objectives: This study was conducted to determine the effects of GSE administration on the metabolic status of female volleyball players. Methods: This randomized, double-blind, placebo-controlled clinical trial was performed among 40 female volleyball players. The subjects were randomly divided into two groups, with members of the test group (n = 20) taking 300 mg of GSE twice a day for eight weeks and members of the control group (n = 20) taking a placebo pearl for the same period. Fasting blood samples were taken before and after the eight-week intervention period in order to determine the related variables. Results: Supplementation with GSE resulted in a significant rise in the plasma glutathione (GSH) level (+265.5 ± 344.2 vs. +2.2 ± 378.2 µmol/L, P = 0.02), as well as a significant decrease in the malondialdehyde (MDA) level (-1.4 ± 2.0 vs. -0.2 ± 1.2 µmol/L, P = 0.01) when compared to the placebo group. In addition, when compared to the group that received the placebo, the subjects who received GSE had significantly decreased serum insulin concentrations (-23.4 ± 23.4 vs. +1.8 ± 25.2 pmol/L, P = 0.002), a decreased homeostasis model of assessment for insulin resistance (HOMA-IR) (-0.7 ± 0.7 vs. +0.2 ± 0.9, P = 0.002), and an increased quantitative insulin sensitivity check index (QUICKI) (+0.01 ± 0.01 vs. -0.01 ± 0.02, P = 0.03). The administration of GSE had no significant effects on creatine phosphokinase (CPK), total antioxidant capacity (TAC), nitric oxide (NO), fasting plasma glucose (FPG), and lipid concentrations when compared with the administration of the placebo. However, after controlling for baseline NO levels, age, and baseline BMI, the changes in the plasma NO concentrations were significantly different between the two groups. Conclusions: In conclusion, taking GSE for eight weeks had beneficial effects on the plasma GSH, MDA levels, and markers of insulin metabolism of female volleyball players. 

Retracted: No

PubPeer comments:
 There are many concerns about the integrity of 172 publications by this research group, including this one. Some of the concerns are published 1. Anaesthesia 2020;75:1683u201392, see Supplementary data. This paper is A78 2. Account Res 2020;28:149-61. 3. J Clin Epidemiol 2021;131:22-29. Journals and publishers were notified of these concerns in July 2019. 23 publications have an expression of concern. To our knowledge there has been no public response about any of the concerns. We think these publications are unreliable ,