High Phenolic Olive Oil for Enhancing Metabolic Health: a Randomized-controlled Trial in Patients With cEntral Obesity (HOPE)

NCT07445503 | Recruiting

• 1 other identifier: 4213/21-02-2025
• Study Type: interventional
• Target: 80
• Locations: 1 country
• Sites: 1

Brief Summary

Olive oil is a fundamental component of the Mediterranean diet and a major source of monounsaturated fatty acids with well-established cardioprotective properties. When rich in phenolic compounds-such as hydroxytyrosol, tyrosol, oleuropein, oleocanthal, oleacein, and ligstroside aglycone-it is considered a functional food with antioxidant, anti-inflammatory, cardioprotective, chemoprotective, and neuroprotective effects. According to EU Regulation 432/2012, daily consumption of 20 g of extra virgin olive oil containing at least 5 mg of hydroxytyrosol and tyrosol derivatives (250 mg/kg) contributes to the protection of blood lipids from oxidative stress and qualifies for a health claim. Overweight/obesity, characterized by excessive fat accumulation, is strongly associated with non-communicable diseases, including cardiovascular disease, type 2 diabetes, hypertension, certain cancers, and neurodegenerative disorders. Chronic low-grade inflammation and oxidative stress are key mechanisms underlying obesity-related metabolic disorders. Although dietary energy restriction remains the primary approach for weight management, growing research interest focuses on natural products rich in phenolic compounds as potential modulators of molecular pathways involved in central obesity. However, robust clinical evidence in humans with central obesity and metabolic abnormalities remains limited. Therefore, this double-blind, randomized, controlled trial aims to investigate the effects of extra virgin, high-phenolic olive oil (HPOO) compared with low-phenolic olive oil (LPOO) in adults with overweight/obesity with metabolic abnormalities. Participants will consume the assigned olive oil type (HPOO or LPOO) for eight weeks. At baseline and trial endpoint (8 weeks), data collection will include anthropometric measurements, dietary intake, biochemical indices, inflammatory and oxidative stress markers in blood samples, hormones, bioavailability of phenolic compounds, as well as lifestyle parameters i.e., health-related quality of life, physical activity levels, sleep quality. Ethical approval, informed consent, and data protection procedures will be strictly followed. Statistical analyses will be conducted using SPSS software (SPSS Inc, ΙΒΜ, Chicago, IL, USA). The study is anticipated to explore whether consumption of high-phenolic olive oil favorably modulates markers related to obesity and metabolic abnormalities, while also improving nutritional status and quality-of-life parameters.

Conditions

Adults; Overweight , Obesity; Metabolic Abnormalities; Consented to Participate in the Trial and Signed an ICF

Keywords

extra virgin, high-phenolic olive oil; overweight; obesity; metabolic disorders; metabolism; oxidative stress; inflammation

Outcome Measures

Primary Outcomes (1)

• Statistically significant change of blood triglyceride levels between the two olive oil groups at the trial endpoint.

  Trial endtpoint (8 weeks)

Secondary Outcomes (3)

• Statistically significant change of blood pressure between the two olive oil groups at the trial endpoint.

  Trial endpoint (8 weeks)

• Statistically significant change of fasting glucose levels between the two olive oil groups at trial endpoint.

  Trial endpoint (8 weeks)

• Statistically significant change of low-density lipoprotein (LDL) levels between the two olive oil groups at trial endpoint.

  Trial endpoint (8 weeks)

Study Arms (2)

Control arm

SHAM COMPARATOR

Participants assigned to the control arm receive olive oil with a low content in phenolic compounts.

Other: Low phenolic olive oil

Intervention arm

ACTIVE COMPARATOR

Participants assigned to the intervention arm receive extra virgin olive oil rich in phenolic compounds.

Other: High phenolic olive oil

Interventions

Low phenolic olive oil OTHER

Olive oil with low content of phenolic compounds.

Control arm

High phenolic olive oil OTHER

Extra virgin olive oil rich in phenolic compounds.

Intervention arm

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adult men and women 18-80 years of age,
• Overweight/obesity (body mass index \> 25 or waist circumference \>94 cm for males and \>80 cm for females), and
• The presence of at least one of the following metabolic abnormality: (1) triglyceride level ≥150 mg/dL or HDL cholesterol ≤40 mg/dL in men and ≤50 mg/dL in women; (2) increased blood pressure ≥ 130/85 mm Hg; (3) elevated fasting blood sugar ≥100 mg/dL; (4) standardized drug treatment regimen, and
• Provided signed informed consent for participation.

You may not qualify if:

• Concomitant acute or chronic disease (e.g., infection, cancer, chronic heart failure, kidney disease, autoimmune diseases like rheumatoid arthritis, inflammatory bowel diseases, Hashimoto),
• Untreated diabetes,
• Women at pregnancy or lactation,
• Individuals with psychiatric or mental disorder,
• Any use of antioxidant-phytochemical rich supplement, anti-, pre- or probiotics pre-intervention,
• Drug and/or alcohol abuse,
• Those who did not consent or were unable to provide consent.

Sponsors & Collaborators

• University of Peloponnese: lead
• Harokopio University: collaborator
• University of the Aegean: collaborator

Study Sites (1)

Antikalamos Facilities of University of Peloponnese

Kalamata, 24100, Greece

RECRUITING

MeSH Terms

Conditions

Overweight; Obesity; Metabolic Diseases; Inflammation

Condition Hierarchy (Ancestors)

Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Pathologic Processes

Study Officials

• Aristea Gioxari

  Department of Nutritional Science and Dietetics, School of Health Sciences, University of Peloponnese

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Aristea Gioxari, Assistant Professor

CONTACT

+302721045326; a.gioxari@go.uop.gr

Alexandra Foscolou, PhD

CONTACT

+306932621082; alexandra.foscolou@go.uop.gr

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor in "Clinical Nutrition and Macronutrient Metabolism"

Model Details: double-blind, parallel group, randomized-controlled trial

Study Record Dates

• First Submitted: February 20, 2026
• First Posted: March 3, 2026
• Study Start: March 3, 2025
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): May 1, 2027
• Last Updated: March 3, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will not share

Locations

GR (1)