The Effects of N-acetylcysteine on Performance and Redox Homeostasis

April 20, 2017 updated by: Vassilis Paschalis, Aristotle University Of Thessaloniki

N-acetylcysteine Supplementation in Individuals With Low Glutathione Levels: the Effects on Physical Performance and Redox Homeostasis

The main objective of the present study was to investigate whether N-acetylcysteine supplementation in individuals with low glutathione levels would confer ergogenic effects by replenishing glutathione levels and by reducing oxidative stress. Towards this aim, investigators sought to exploit the large inter-individual variability in redox biomarker levels. More specifically, investigators screened 100 male participants for glutathione baseline levels in blood and formed three stratified groups according to this value (i.e., low, moderate and high; 12 individuals per group). After by-passing the regression to the mean artefact by performing a second glutathione measurement in the three aforementioned groups, investigators assessed both aerobic and anaerobic physical performance in order to acquire a more comprehensive view about the ergogenic effectiveness of the antioxidant treatment. This was accomplished by implementing three different whole-body physical performance tests (i.e., VO2max test, time trial and Wingate), as opposed to most in vivo studies that either applied isolated body-part exercise tests (e.g., by isokinetic dynamometry) or performed a single exercise test (e.g., time-to-fatigue test). It was hypothesised, that data of the present investigation will bridge the chasm between the scientific (i.e., chronic antioxidant supplementation blunts exercise performance and adaptations) and the community-based (i.e., free radicals should anyway be counteracted by "protective" exogenous antioxidants) truths about the role of antioxidants as ergogenic aids. It was also hypothesised that the results will show that low glutathione levels are linked to decreased aerobic and anaerobic physical performance accompanied by increased levels of oxidative stress and that N-acetylcysteine supplementation will restore both performance and redox homeostasis. Based on the findings of the present investigation, the widespread routine practice of consuming antioxidants during exercise training could be changed and the consumption of antioxidants would be restricted only for those who are deficient in glutathione.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

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Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
36

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Cyprus
      • Nicosia, Cyprus, 1516
        • European University Cyprus
  • Greece
      • Athens, Greece, 17237
        • National and Kapodistrian University of Athens
      • Thessaloniki, Greece, 54124
        • Aristotle University of Thessaloniki

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 29 years (ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

Male

Description

Inclusion Criteria:

  • Healthy male subjects who participated recreationally in physical activities less than 3 times per week.

Exclusion Criteria:

  • Subjects were excluded from the study, if they reported any musculoskeletal injury that would limit their ability to perform the exercise sessions. Participants were asked to recall whether they had participated in regular resistance or aerobic training or in unaccustomed exercise during the period before the study entry. Individuals who reported such activities were precluded from the study. Smoking and consumption of antioxidant supplements the days prior to the study were additional exclusion criteria.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: SCREENING
  • Allocation: RANDOMIZED
  • Interventional Model: PARALLEL
  • Masking: SINGLE

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
PLACEBO_COMPARATOR: Lactose
The placebo group received orally two lactose tablets per day for 30 days. Each individual received the capsules pre-packed in daily doses labeled with the day of consumption.
Drug: Lactose
The placebo group received orally two lactose tablets per day. The participants were instructed to receive the capsules every twelve hours. Each individual received the capsules pre-packed in daily doses labeled with the day of consumption. The supplementation period was 30-day for placebo.
EXPERIMENTAL: N-acetylcysteine
The antioxidant group received orally two N-acetylcysteine tablets (each tablet contained 600 mg of NAC; Lamberts Health Care Ltd, Kent, United Kingdom). The participants were instructed to receive the capsules every twelve hours in order to achieve high concentration of N-acetylcysteine throughout the 24 h. Each individual received the capsules pre-packed in daily doses labeled with the day of consumption.
Drug: N-acetylcysteine
The antioxidant group received orally two N-acetylcysteine tablets (each tablet contained 600 mg of NAC; Lamberts Health Care Ltd, Kent, United Kingdom). The participants were instructed to receive the capsules every twelve hours in order to achieve high concentration of N-acetylcysteine throughout the 24 h. Each individual received the capsules pre-packed in daily doses labeled with the day of consumption. The supplementation period was 30-day for N-acetylcysteine.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Measurement of maximal oxygen consumption (ml/kg/min)
Time Frame: 64 days

Maximal oxygen consumption was assessed (using incremental cycling test to volitional exhaustion) on cycle ergometers (Monark, Vansbro, Sweden). Briefly, after a 5-min warm-up period at 100W, workload increased by 50W every 2.5 minutes until heart rate reached 160 bpm. Then, workload increased by 25W every 2.5 minutes until exhaustion. Respiratory gas variables were measured using a metabolic cart (Quark b2, Cosmed, Italy), which was calibrated before each test using standard gases of known concentration.

Maximal oxygen consumption along with time trial and wingate test were used for assessing both aerobic and anaerobic physical performance in order to acquire a more comprehensive view about the ergogenic effectiveness of the antioxidant treatment.
64 days

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Measurement of glutathione levels (μmol/g Hb)
Time Frame: 64 days

Erythrocyte GSH was determined spectrophotometrically. 20 μL of erythrocyte lysate treated with 5% TCA mixed with 660 μL of67 mMsodium potassium phosphate (pH 8.0) and 330 μL of 1mM 5,5- dithiobis-2 nitrobenzoate. The samples were incubated in the dark at room temperature for 45 min, and the absorbance was read at 412 nm.

The measurement of glutathione was used for assessing the efficacy of NAC supplementation to restore glutathione levels in the low-glutathione group as well as the effects of NAC supplementation in the medium and high glutathione groups.
64 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Aristotle University Of Thessaloniki

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National and Kapodistrian University of Athens
European University Cyprus

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Michalis Nikolaidis, PhD, Aristotle University of Thessaloniki

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (ACTUAL)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 1, 2015

Primary Completion (ACTUAL)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
February 15, 2016

Study Completion (ACTUAL)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 12, 2016

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 6, 2017

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 17, 2017

First Posted (ACTUAL)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 20, 2017

Study Record Updates

Last Update Posted (ACTUAL)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 21, 2017

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 20, 2017

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2017

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 83022/2015

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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