Oxidative Stress, Carbohydrate Metabolism Disorders and G6PD Deficiency

The Association Between Oxidative Stress and Carbohydrate Metabolism Disorders in G6PD Deficient Individuals

The purpose of this study is to investigate the effects of alpha-lipoic acid supplementation on redox status, physiological and biochemical parameters in diabetic individuals with G6PD deficiency, after acute exercise.

In a randomized double-blind, crossover design, a total of forty people will participate in the research voluntarily: (a) ten people with G6PD (Mediterranean type) enzyme deficiency), (b) ten people with G6PD (Mediterranean type) enzyme deficiency and a disorder of carbohydrate metabolism (diabetes, prediabetes), (c) ten people with a disorder of carbohydrate metabolism (diabetes mellitus and prediabetes) and, (d) ten people without any health problem (control group). They will be supplemented with either 600 mg of alpha-lipoic acid (experimental condition) or placebo (control condition) every day for 4 weeks, separated by a 4-week washout period. All participants will be randomly assigned to both conditions. Before intervention, all participants will be informed about the study protocol, fill a medical history questionnaire and sign an informed consent form. Moreover, measurements of anthropometric characteristics and physiological parameters, as well as a VO2peak test will be performed. Participants will perform a trial of exercise (70% VO2peak for 45min and 90% till exhaustion) before and after each condition (i.e. a total of 4 trials). Blood samples will be collected before, immediately after and 1 hour after each exercise trial. Moreover, measurements of anthropometric characteristics, physiological and psychological parameters will be performed before and after each condition.

Alpha-lipoic acid supplementation (600 mg/day) for 4 weeks in a counterbalanced manner to 10 G6PD deficient individuals.

Alpha-lipoic acid supplementation (600 mg/day) for 4 weeks in a counterbalanced manner to 10 individuals with G6PD deficiency and a CHO metabolism disorder.

Placebo for 4 weeks in a counterbalanced manner to 10 individuals with G6PD deficiency and a CHO metabolism disorder.

Alpha-lipoic acid supplementation (600 mg/day) for 4 weeks in a counterbalanced manner to 10 individuals with a CHO metabolism disorder.

Alpha-lipoic acid supplementation (600 mg/day) for 4 weeks in a counterbalanced manner to 10 individuals without G6PD deficiency and/or any CHO metabolism disorder.

Placebo for 4 weeks in a counterbalanced manner to 10 individuals without G6PD deficiency and/or any CHO metabolism disorder.

Changes in total antioxidant capacity following 4 weeks of supplementation and placebo at rest and following a trial of acute exercise.

Index of blood redox status. Spectrophotometric assay for the determination of total antioxidant capacity using DPPH method.

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Changes in glutathione following 4 weeks of supplementation and placebo at rest and following a trial of acute exercise.

Index of blood redox status. Spectrophotometric assay for the determination of total antioxidant capacity using DTNB method.

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Changes in uric acid following 4 weeks of supplementation and placebo at rest and following a trial of acute exercise.

Index of blood redox status. Spectrophotometric assay for the determination of total antioxidant capacity using a clinical chemistry analyzer with commercially available kits.

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Changes in bilirubin following 4 weeks of supplementation and placebo at rest and following a trial of acute exercise.

Index of blood redox status. Spectrophotometric assay for the determination of bilirubin using a clinical chemistry analyzer with commercially available kits.

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Changes in lipid peroxidation following 4 weeks of supplementation and placebo at rest and following a trial of acute exercise.

Index of blood redox status. Determination of lipid peroxidation using malondialdehyde production assessment.

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Changes in protein carbonyls following 4 weeks of supplementation and placebo at rest and following a trial of acute exercise.

Index of blood redox status. Spectrophotometric assay for the determination of total antioxidant capacity using DNPH method.

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Changes in blood lipids following 4 weeks of supplementation and placebo at rest and following a trial of acute exercise.

Blood lipids (total cholesterol, LDL-c, HDH-c, triglycerides). Spectrophotometric assays for the determination of blood lipids using a clinical chemistry analyzer with commercially available kits.

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Measurement of blood glucose and insulin levels to assess HOMA-IR and evaluate insulin resistance. Spectrophotometric assay for the determination of blood glucose using a clinical chemistry analyzer with commercially available kits.Determination of blood insulin using commercially available Eliza kits.

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)

Quantification of G6PD activity in erythrocytes (units/gram of hemoglobin) of all participants using a commercially available kit.

Before intervention. During GTT (blood samples at 0, 30, 60, 90 and 120 minutes after intake of 75 g glucose). Also before, immediately after and 1, 2, 24 hours after each trial of exercise, in both conditions (supplement and placebo).

Inclusion Criteria: Individuals with normal G6PD activity Individuals with G6PD deficiency Individuals with CHO metabolism disorders (diabetes, prediabetes) Individuals with G6PD deficiency and CHO metabolism disorders (diabetes, prediabetes) Exclusion Criteria: Health problems that contraindicate participation to exercise Should not take any medication that affects the body's antioxidant mechanisms as well as dietary supplements containing antioxidants Women during lactation or gestation

Georgakouli K, Deli CK, Zalavras A, Fatouros IG, Kouretas D, Koutedakis Y, Jamurtas AZ. Alpha-lipoic acid supplementation up-regulates antioxidant capacity in adults with G6PD deficiency. Food Chem Toxicol. 2013 Nov;61:69-73. doi: 10.1016/j.fct.2013.01.055. Epub 2013 Feb 14.