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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
40
A trial of acute exercise before and after 4 weeks of alpha-lipoic acid supplementation.
A trial of acute exercise before and after 4 weeks of placebo supplementation.
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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)
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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.
Time frame: 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.
Time frame: Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)
Changes in insulin resistance following 4 weeks of supplementation 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.
Time frame: Before and following 4 weeks of supplementation and placebo.
Changes in glycated hemoglobin (HbA1c) following 4 weeks of supplementation and placebo.
Measurement of HbA1c using commercially available kits.
Time frame: Before and following 4 weeks of supplementation and placebo.
Changes in body composition following 4 weeks of intervention and placebo.
Body fat mass (in kg) and percentage, lean mass (in kg) and percentage
Time frame: Before and following 4 weeks of supplementation and placebo.
Changes in body mass index following 4 weeks of intervention and placebo.
Body mass (in kg) and height (in cm)
Time frame: Before and following 4 weeks of supplementation and placebo.
Changes in resting heart rate following 4 weeks of intervention and placebo.
Resting heart rate (beats per minute) measurement after at least 5 minutes at rest
Time frame: Before and following 4 weeks of supplementation and placebo.
Changes in blood pressure following 4 weeks of intervention and placebo.
Measurement of (systolic and diastolic) blood pressure (in mm Hg) after at least 5 minutes at rest
Time frame: Before and following 4 weeks of supplementation and placebo.
Changes in waist-to-hip ratio following 4 weeks of intervention and placebo.
Measurement of waist and hip circumference to calculate waist-to-hip ratio
Time frame: Before and following 4 weeks of supplementation and placebo.
Changes in complete blood count following 4 weeks of intervention and placebo.
Complete blood count
Time frame: Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)
Changes in psychometric test following 4 weeks of intervention and placebo.
Hospital Anxiety Depression Scale-HADS (Greek version)
Time frame: Before and following 4 weeks of supplementation and placebo.
Trial of VO2peak estimation.
VO2peak (mL/kg body weight/min) estimation with a treadmill protocol.
Time frame: Before intervention.
Nicotinamide-adenine dinucleotide phosphate (NADPH)
Spectrophotometric assay for the determination of NADPH in erythrocytes.
Time frame: Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)
Glutathione Reductase (GR)
Spectrophotometric assay for the determination of GR in erythrocytes.
Time frame: Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)
Glutathione peroxidase (GPx)
Spectrophotometric assay for the determination of GPx in erythrocytes.
Time frame: Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)
Superoxide dismutases (SOD)
Spectrophotometric assay for the determination of SOD in erythrocytes.
Time frame: Before, immediately after and 1 hour after each trial of exercise, in both conditions (supplement and placebo)
Glucose Tolerance Test (GTT)
GTT for the investigation of changes in glucose control.
Time frame: Before intervention (blood samples at 0, 30, 60, 90 and 120 minutes after intake of 75 g glucose).
G6PD enzyme activity in erythrocytes
Quantification of G6PD activity in erythrocytes (units/gram of hemoglobin) of all participants using a commercially available kit.
Time frame: 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).