Krill Oil and Metformin in Women With PCOS and Metabolically Unhealthy Obesity

May 17, 2026 updated by: Murat Açık, Firat University

Effects of Krill Oil and Metformin on Cardiometabolic, Adipokine, Hormonal, and Fatty Acid Profiles in Women With Polycystic Ovary Syndrome and Metabolically Unhealthy Obesity: An Open-Label, Randomized, Parallel-Group Pilot Trial

This open-label, randomized, parallel-group pilot trial investigated the effects of krill oil, metformin, and their combination on adipokine profiles, cardiometabolic risk markers, and serum fatty acid composition in women with polycystic ovary syndrome (PCOS) and metabolically unhealthy obesity (MUO). Eligible women aged 19-40 years with PCOS according to Rotterdam criteria and MUO based on combined NCEP ATP-III/IDF criteria were allocated to three 8-week interventions: continuation of standard metformin therapy (MET), krill oil supplementation alone (KO), or metformin plus krill oil (METKO). Metformin users were stratified and randomized 1:1 to MET or METKO, while metformin-naive participants were assigned to KO. Krill oil (Superba Boost, Aker BioMarine) was administered at 2,000 mg/day (approximately 400 mg EPA and 240 mg DHA) and metformin at 1,000 mg/day. Primary outcomes were changes in serum adiponectin and neuregulin-4 (NRG-4) measured by ELISA. Secondary outcomes included anthropometric indices, fasting glucose, insulin, HOMA-IR, lipid profile, reproductive hormones, and detailed serum fatty acid profiling by GC-MS, as well as Mediterranean Diet Adherence Screener (MEDAS) scores. The trial aimed to provide preliminary evidence on whether adding krill oil to metformin therapy offers broader metabolic benefits than either intervention alone in women with PCOS and MUO.

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.

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.
54

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

  • Turkey (Türkiye)
      • Elâzığ, Turkey (Türkiye), 23119
        • Firat University, Faculty of Health Sciences, Department of Nutrition and Dietetics

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

No

Description

Inclusion Criteria:

  1. Female sex, aged 19-40 years
  2. Diagnosis of Polycystic Ovary Syndrome (PCOS) according to Rotterdam criteria (at least 2 of 3: oligo/anovulation, clinical/biochemical hyperandrogenism, polycystic ovaries on ultrasound)
  3. Metabolically Unhealthy Obesity (MUO) defined by combined NCEP ATP-III/IDF criteria (waist circumference >88 cm plus ≥2 metabolic risk factors)
  4. BMI ≥ 30 kg/m2
  5. Willingness to provide written informed consent

Exclusion Criteria:

  1. Type 1 or Type 2 diabetes mellitus
  2. Thyroid disorders (uncontrolled hypo- or hyperthyroidism)
  3. Renal or hepatic disease
  4. Cardiovascular disease
  5. Use of oral contraceptives, insulin sensitizers, lipid-lowering drugs, or omega-3 supplements in the past 3 months
  6. Pregnancy or lactation
  7. Allergy to fish or seafood (krill oil contraindication)
  8. Participation in another clinical trial
  9. Smokers or alcohol users

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: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel 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: Metformin Group (MET)
Participants received Metformin Hydrochloride 1000 mg/day (single daily oral dose) for 8 weeks. No dietary supplement was added in this group.
Drug: Metformin Hydrochloride 1000 MG
Metformin Hydrochloride 1000 mg/day (single daily oral dose) for 8 weeks. Metformin is a biguanide antidiabetic drug that improves insulin sensitivity and reduces hepatic glucose production. Used as standard treatment for PCOS-related insulin resistance and metabolic dysfunction.
Experimental: Krill Oil Group (KO)
Participants received Krill Oil 2 g/day (1 g twice daily, orally) for 8 weeks. No pharmaceutical agent was administered in this group.
Dietary supplement: Krill Oil
Krill Oil 2 g/day (1 g twice daily, oral administration) for 8 weeks. Krill oil is a marine-derived omega-3 fatty acid supplement rich in EPA, DHA, and phospholipids with antioxidant astaxanthin. It has anti-inflammatory, lipid-modulating, and insulin-sensitizing properties relevant to PCOS and metabolic obesity management.
Experimental: Metformin + Krill Oil Group (METKO)
Participants received Metformin Hydrochloride 1000 mg/day (single daily oral dose) combined with Krill Oil 2 g/day (1 g twice daily, orally) for 8 weeks.
Drug: Metformin Hydrochloride 1000 MG
Metformin Hydrochloride 1000 mg/day (single daily oral dose) for 8 weeks. Metformin is a biguanide antidiabetic drug that improves insulin sensitivity and reduces hepatic glucose production. Used as standard treatment for PCOS-related insulin resistance and metabolic dysfunction.
Dietary supplement: Krill Oil
Krill Oil 2 g/day (1 g twice daily, oral administration) for 8 weeks. Krill oil is a marine-derived omega-3 fatty acid supplement rich in EPA, DHA, and phospholipids with antioxidant astaxanthin. It has anti-inflammatory, lipid-modulating, and insulin-sensitizing properties relevant to PCOS and metabolic obesity management.
No Intervention: Control Group
Participants received no intervention during the 8-week study period. They continued their habitual lifestyle without any dietary supplementation or pharmaceutical treatment.

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
Change in Serum Adiponectin Level
Time Frame: 8 weeks (Baseline and Week 8)
Change in serum adiponectin concentration measured by ELISA at baseline and after 12 weeks of intervention. Adiponectin is an anti-inflammatory adipokine associated with insulin sensitivity and metabolic health.
8 weeks (Baseline and Week 8)
Change in Serum Neuregulin-4 (NRG-4) Level
Time Frame: 8 weeks (Baseline and Week 8)
Change in serum neuregulin-4 (NRG-4) concentration measured by ELISA at baseline and after 12 weeks of intervention. NRG-4 is a novel adipokine linked to lipid metabolism, brown adipose tissue activity, and cardiometabolic health.
8 weeks (Baseline and Week 8)

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
Change in Insulin Resistance (HOMA-IR)
Time Frame: 8 weeks (Baseline and Week 8)
Change in homeostatic model assessment of insulin resistance (HOMA-IR) calculated from fasting glucose and fasting insulin levels at baseline and 12 weeks.
8 weeks (Baseline and Week 8)
Change in Lipid Profile (Total Cholesterol, LDL-C, HDL-C, Triglycerides)
Time Frame: 8 weeks (Baseline and Week 8)
Changes in fasting serum total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride concentrations measured at baseline and 12 weeks.
8 weeks (Baseline and Week 8)

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.
Firat 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.
March 1, 2023

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.
April 30, 2024

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.
April 30, 2024

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).
May 17, 2026

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.
May 17, 2026

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.
May 22, 2026

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.
May 22, 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.
May 17, 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.
May 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.
  • FU_MAcik_PCOS_KO_2023

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared publicly. This is an academic pilot study and the data will be available upon reasonable request to the corresponding author.

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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