Effect of Proteins on Antioxidant Capacity

July 20, 2026 updated by: Aslı Onur Canaydın, TC Erciyes University

Effect of High Protein Diet on Total Antioxidant Capacity

This study was planned to provide information about the effect of short-term high protein diet (HPD) feeding on early antioxidant response in women. The definition of HPDs cannot be determined exactly. It is defined differently by various scientific authorities. However, protein is targeted to be approximately 30% of total energy in HPD. It has been determined that HPDs increase satiety, thermogenesis, and provide body weight loss and maintenance of loss. In general, there is evidence that HPD provides more body weight loss in a short time compared to low protein diets. It has been emphasized that the effect of high protein diet on weight loss is related to creating satiety, thus decreasing food intake and increasing thermogenesis. However, the physiological, biochemical and molecular events that occur due to HPD feeding have not been fully understood and the results have not been explained. The effects of HPDs have been determined to last from 1 to 6 days to 6 months. The absence of any study in the literature on the short-term and long-term effects of HPD on oxidative events in humans reveals the original value of this study. Therefore, considering that long-term HPD feeding may increase the risk of cardiovascular disease, blood pressure, and blood lipid levels, the effect of short-term HPD feeding on antioxidant capacity will be investigated in order to avoid these side effects. The planned interviews and measurements for this prospective analytical study will be carried out in the Anthropometry laboratory of the Department of Nutrition and Dietetics, Faculty of Health Sciences at Erciyes University, and blood analyses will be carried out in the Betül Ziya Eren Genome and Stem Cell Research Center laboratory and the Erciyes University Gülser and Dr. Mustafa Gündoğdu Comprehensive Service Laboratory. Healthy female individuals will be applied HPD for 10 days and a normal diet for 10 days as a control. As a result of the applied diets, the expected results of the study are that HPD will cause a decrease in body weight and an increase in lean body mass, even for a short time, and that HPD will have an effect on diet-induced inflammation, cause oxidative stress, affect antioxidant capacity and cause changes in the measured parameters.

Study Overview

Status

Status

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

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

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.

Detailed Description

Today, most individuals try various nutritional models/diets to reduce body weight. One of the most popular of these diets is the diets that reduce carbohydrate intake. Western societies generally avoid high carbohydrates and fat intake. For this reason, interest in high protein intake in diets is increasing day by day. Although there is no general consensus on what a high-protein diet is, the high protein diet (HPD) applied for weight loss studies is diets that contain approximately 30% of the energy provided by protein. The World Health Organization (WHO) has defined obesity as an endemic public problem and stated that its prevalence is increasing. With the increase in obesity, individuals try various dietary modifications to achieve weight loss. These include diets with a more regular macro and micronutrient pattern, such as the Mediterranean Diet and the DASH diet, and diets that may cause deficiencies in terms of macro and micronutrients, such as Atkins, South Beach, Zone, and Stillman, which contain high protein. The most important reasons why high-protein diets attract attention are that they cause rapid weight loss and provide satiety. This positive effect of HPDs on weight loss has attracted the attention of dietitians and caused them to increase the protein ratio in diets. Scientific authorities against popular diets; what is really known about popular diets, the scientific nature of the information, whether it is effective in maintaining body weight, if it is effective, its effect on body composition, micronutrient level, metabolic indicators, hunger-satiety, psychological state, chronic disease risk, its effect on leptin and insulin levels, which provide hormone regulation in long-term energy intake and expenditure.

It is known that HPDs provide more effective results in body weight loss compared to low protein diets. It is suggested that this effect occurs as a result of increased thermogenesis, increased satiety and suppressed appetite, and reduced glycemic index and glycemic load due to the replacement of refined carbohydrates with proteins. In addition to this positive effect on weight loss, there are possible short- and long-term side effects of HPD nutrition. Known complications of long-term HPD nutrition include increased cardiovascular disease risk, blood pressure, blood lipids, and kidney dysfunction. Cardiovascular problems in particular are a source of concern because they will counteract the short-term positive effect of HPD on weight loss and increase the burden of cardiovascular disease in the long term. Studies generally focus on HPD and weight loss; there is limited data on the relationship between HPD nutrition and metabolic dysfunction such as endothelial dysfunction, inflammatory markers, antioxidant status, and other chronic diseases. The physiological, biochemical, and molecular events that occur due to high protein diet nutrition have not been fully understood and their results have not been explained.

High protein diets (especially low carbohydrate diets) are thought to have negative effects because they cause a decrease in fruit and vegetable consumption. In those who eat a HPD, especially inadequate vitamin A, C and E in their diets, this will have a negative effect on antioxidant systems and will pave the way for the development of many chronic and metabolic diseases in the long term. Despite the positive effects of HPD applied as a weight loss diet in the short term, it is thought that the oxidative stress and inflammation it will create in the long term will cause an increase in chronic and metabolic diseases as well as comorbidities. This increase in the disease burden will increase health expenditures both individually and socially.

Therefore, this study was planned to provide information about the effect of short-term HPD feeding on early antioxidant response in adult, healthy, normal body mass index female individuals. As a result of the study, it is thought that short-term HPD feeding will cause an increase in oxidative stress, a decrease in antioxidant capacity and an increase in inflammatory biomarkers.

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.
20

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.
  • Not Applicable

Contacts and Locations

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

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Turkey (Türkiye)
    • Melikgazi
      • Kayseri, Melikgazi, Turkey (Türkiye), 38030
        • Erciyes University

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

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Being between 19-45 years of age,
  • Not changing physical activity throughout the study,
  • Having a BMI of 18.5-24.9 kg/m2,
  • Being healthy

Exclusion Criteria:

  • Having a BMI of <18.5 and ≥25 kg/m2,
  • Having a chronic disease,
  • Smoking and drinking alcohol,
  • Using vitamin-mineral supplements and herbal supplements,
  • Being pregnant or breastfeeding,
  • Having entered menopause,
  • Being on any diet.

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: Other
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

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.
Experimental: Fixed-Sequence Dietary Intervention
All participants received the same fixed sequence of dietary interventions. Participants first received a high-protein diet for 10 days (40% carbohydrate, 30% protein, and 30% fat), followed by a two-week wash-out period during which they maintained their habitual dietary intake. They subsequently received a normal-protein diet for 10 days (55% carbohydrate, 15% protein, and 30% fat). Participants were instructed not to consume foods or beverages other than those permitted by the study protocol during both intervention periods. The intervention order was not randomized.
Other: High Protein Diet
Individuals will be placed on a high protein diet for 10 days.
Other: Normal Protein Diet
Individuals will be placed on a normal protein diet for 10 days.

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
Antioxidant capacity after high protein diet
Time Frame: Day after diet end
After the diet, antioxidant biomarkers [antioxidant status (TAS), total oxidant status (TOS)] will be measured in the blood. Lower values represent a worse outcome.
Day after diet end
Anthropometric measurements after high protein diet
Time Frame: Day after diet end
Anthropometric measurements will be made after the diet. An increase in anthropometric measurements represents a worse result.
Day after diet end

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.
TC Erciyes University

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.
September 25, 2024

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.
September 25, 2025

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 25, 2025

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).
September 19, 2024

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.
September 27, 2024

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.
October 1, 2024

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.
July 21, 2026

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.
July 20, 2026

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.
July 1, 2026

More Information

Terms related to this study

Keywords

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.
  • ERU-BES-AOC-02

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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