Evaluation of the Antioxidant and Anti-Inflammatory Capacities of the 'Rosy Red Valencia' and 'Olinda Valencia' Sweet Orange Varieties in Healthy Subjects

This study aims to evaluate the antioxidant and anti-inflammatory effects of acute and chronic consumption of two sweet orange (Citrus sinensis) varieties-'Rosy Red Valencia', which is rich in carotenoids such as lycopene, phytoene, and phytofluene, and 'Olinda Valencia', which lacks these carotenoids-in healthy adults. In this 4-week, randomized, parallel-arm clinical trial, participants will consume either 'Rosy Red Valencia' or 'Olinda Valencia' oranges daily. The study will assess the effects of sweet orange intake on markers of oxidative stress and inflammation, plasma carotenoid concentrations, gene expression in peripheral blood mononuclear cells, and gut health. Findings from this study may help identify potential health benefits associated with specific carotenoid profiles in sweet oranges and provide insights into their role in modulating inflammation and oxidative stress.

Study Overview

• Status: Completed
• Conditions: Healthy
• Intervention / Treatment: Other: 'Rosy Red Valencia' sweet orange; Other: 'Olinda Valencia' sweet oranges

Detailed Description

The health benefits of orange consumption have been described; however, the specific bioactive compounds responsible for these effects, as well as the underlying mechanisms of action, are not fully understood. There are several varieties of sweet oranges, each with a unique phytochemical profile and potentially distinct health-promoting properties. The 'Rosy Red Valencia' sweet orange is enriched in carotenoids such as lycopene, phytoene, and phytofluene, whereas the commonly consumed 'Olinda Valencia' contains negligible levels of these compounds.

This randomized, parallel-arm clinical trial aims to evaluate and compare the antioxidant and anti-inflammatory effects of 'Rosy Red Valencia' and 'Olinda Valencia' sweet orange consumption in healthy men and women. Participants will be randomized to consume one of the two orange varieties twice daily for four weeks.

The study includes both an acute phase (1-day consumption) and a chronic phase (4-week daily consumption). Blood samples will be collected at baseline, after 1 day, and after 4 weeks of consumption to assess changes in plasma carotenoid concentrations, markers of oxidative stress and inflammation, and gene expression profiles in peripheral blood mononuclear cells. Fecal samples will be collected at baseline and after 4 weeks to assess the effects on gut microbiota composition. By evaluating and comparing the biological effects of these two orange varieties, the study aims to elucidate the role of specific carotenoids in mediating the health benefits of sweet orange consumption.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • Davis, California, United States, 95616
      • Nutrition Department, Ragle Facility, University of California Davis

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria

• Healthy men and women
• Age Range: 25-40 years
• Body mass index (BMI) with values between 21 and 29.9 kg^m2
• Willingness to accept randomization, undergo the testing and intervention procedures, and deliver blood and stool samples
• Willingness to refrain from consuming foods rich in lycopene, phytoene, and phytofluene and limit the intake of some polyphenol-rich foods
• Willingness to discontinue the use of antioxidant supplements (such as carotenoid, polyphenol supplements), prebiotics and/or probiotics

Exclusion Criteria:

• Pregnancy/lactation
• History of cardiovascular diseases, diabetes, uncontrolled hypertension, heart failure, stroke, liver, gallbladder, kidney, thyroid disease, gastrointestinal, autoimmune disorder, or cancer.
• Psychiatric disease that interferes with the understanding and implementation of the intervention
• History of eating disorders (such as bulimia nervosa and anorexia nervosa) in the last 5 years
• Current smokers
• Vegan, vegetarian, or other special diets (e.g., keto, paleo)
• Use of antibiotics or laxatives in the previous month
• History of substance abuse or alcohol abuse
• involvement in a weight loss intervention program within the past month or weight change > 10%
• Self-report of allergic reactions to study products or their phytochemicals.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 'Rosy Red Valencia' sweet orange variety; The participants of this group consume 'Rosy Red Valencia' sweet oranges	Other: 'Rosy Red Valencia' sweet orange; The participants consume 2 'Rosy Red Valencia' sweet oranges daily for 4 weeks
Experimental: 'Olinda Valencia' sweet orange variety; The participants of this group consume 'Olinda Valencia' sweet oranges	Other: 'Olinda Valencia' sweet oranges; The participants consume 2 'Olinda Valencia' sweet oranges daily for 4 weeks

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Levels of lycopene and noncolored carotenoids	Levels in plasma	0, 1 day, 4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gene expression	Gene expression in Peripheral Blood Mononuclear Cells (PBMCs)	0, 1 day, 4 weeks
Lipid/metabolic profile	Measured in blood samples	0, 4 weeks
Microbiota composition	From stool samples	0, 4 weeks
Oxidative stress	Oxidative stress marker DNA/RNA oxidative damage assessed in blood samples from participants by a commercial kit	0, 1 day, 4 weeks
Inflammation	Levels of inflammatory marker CRP assessed in blood samples from participants using commercial assay kits.	0, 1 day, 4 weeks
Systolic and diastolic blood pressure	Measured by automated sphygmomanometer	0, 4 weeks

Collaborators and Investigators

• Sponsor: University of California, Davis
• Investigators: Study Director: Gerardo G Macknezie, PhD, Univeristy of California Davis

Study record dates

Study Major Dates

• Study Start (Actual): May 17, 2025
• Primary Completion (Actual): October 1, 2025
• Study Completion (Actual): March 6, 2026

Study Registration Dates

• First Submitted: April 17, 2025
• First Submitted That Met QC Criteria: April 17, 2025
• First Posted (Actual): April 25, 2025

Study Record Updates

• Last Update Posted (Actual): March 11, 2026
• Last Update Submitted That Met QC Criteria: March 9, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Oxidative stress; Inflammation; Healthy; gene expression; Lycopene; Oranges
• Additional Relevant MeSH Terms: Pathologic Processes; Pathological Conditions, Signs and Symptoms; Inflammation
• Other Study ID Numbers: 22923441

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