Effect of Blueberries on Immunity (Blueberry)

February 2, 2026 updated by: Loma Linda University

Immune Benefits of Blueberry Consumption in Overweight Older Men and Postmenopausal Women: A Randomized Trial

This research study will test the effects of Blueberries on immune functions in overweight older men and postmenopausal women

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

This study will examine the effects of Blueberries on clinically relevant markers of immune function. Eligible and selected participants will be randomized to one of two groups at the baseline clinic visit. The Blueberry group participants will consume blueberries (2 packets of blueberry freeze-dried powder equivalent to 2 cups of fresh blueberries) added to the habitual diet and the Control group participants will abstain from blueberries (with instructions to limit the consumption of other berries and polyphenol rich foods) but otherwise continue their habitual diet. During the study, clinic visits will occur at 4-week intervals (baseline, weeks 4, 8 and 12) for a total of 4 visits at the Loma Linda University Nutrition Research Center. Blood samples taken at baseline and at week 12 will be assayed for changes in immune function and inflammatory markers.

Study Type

Interventional

Enrollment (Actual)

52

Phase

  • 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 Locations

  • United States
    • California
      • Loma Linda, California, United States, 92350
        • Loma Linda University School of Public Health

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

Ages Eligible for Study

50 years to 70 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  1. Older men and post-menopausal women aged 50-70 year
  2. Have BMI of 25-32
  3. Able to commute to Loma Linda University
  4. Consuming a typical American Diet low in polyphenols

Exclusion Criteria:

  1. Intolerance or allergy to Blueberries
  2. Regular intake of Blueberries and other berried (>2 ounces/week)
  3. Immune system insufficiency or disease
  4. Using immune boosting supplements
  5. Exposure to antibiotics and corticoids immediately prior to study
  6. Uncontrolled chronic diseases and relevant psychiatric illness, including major depression
  7. Flu vaccination and or Covid Vaccination less than 3 months ago from the start of the study

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: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Blueberry powder group
Participants in the blueberry powder group will receive freeze dried blueberries in form of a powder
Dietary supplement: Blueberry powder group
Participants in the blueberry powder group will receive freeze dried blueberries in form of a powder
Dietary supplement: Placebo powder group
Participants in the placebo powder group will receive an isocaloric placebo powder
Placebo Comparator: Placebo powder group
Participants in the placebo group will receive an isocaloric placebo powder.
Dietary supplement: Blueberry powder group
Participants in the blueberry powder group will receive freeze dried blueberries in form of a powder
Dietary supplement: Placebo powder group
Participants in the placebo powder group will receive an isocaloric placebo powder

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
changes in lymphocyte populations
Time Frame: baseline to 12 weeks
Immunophenotyping will be performed by flow cytometry to measure the number of T helper, T cytotoxic, Naïve and memory cells and B cells
baseline to 12 weeks
changes in natural killer (NK) cell activity
Time Frame: baseline to 12 weeks
The NK degranulation assay will be performed on blood samples. The test will be conducted using a modified flow cytometry method that measures the expression of CD107a
baseline to 12 weeks
changes in serum inflammatory cytokine concentration
Time Frame: baseline to 12 weeks
Changes in the concentrations of the inflammatory cytokines will be performed on serum using enzyme-linked immunoassay (ELISA)
baseline to 12 weeks
changes in complete blood count (CBC)
Time Frame: baseline to 12 weeks
changes in the complete blood count will be performed on whole blood with the use of an automated hematology analyzer at a certified clinical facility
baseline to 12 weeks
changes in cytokine production
Time Frame: baseline to 12 weeks
PBMC cells will be separated from blood, activated and cultured using phytohemagglutinin (PHA). Inflammatory cytokine production will be measured in the resulting supernatant using ELISA
baseline to 12 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
changes in neutralizing antibody titers against hemagglutinin and neuraminidase of the vaccine strain
Time Frame: week 8 to week 12
Neutralizing antibody titers in the serum against the hemagglutinin and neuraminidase of the vaccine strain will be measured using the standard commercial ELISA kits
week 8 to week 12
changes in the viral load in response to vaccination
Time Frame: week 8 to week 12
viral load in blood will be measured using a quantitative polymerase chain reaction
week 8 to week 12

Collaborators and Investigators

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

Sponsor

Loma Linda University

Collaborators

U.S. Highbush Blueberry Council

Investigators

  • Principal Investigator: Joan Sabate, DrPH, Loma Linda University
  • Principal Investigator: Sujatha Rajaram, PhD, Loma Linda 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)

October 12, 2022

Primary Completion (Actual)

September 12, 2023

Study Completion (Actual)

September 12, 2023

Study Registration Dates

First Submitted

September 6, 2022

First Submitted That Met QC Criteria

September 8, 2022

First Posted (Actual)

September 10, 2022

Study Record Updates

Last Update Posted (Actual)

February 4, 2026

Last Update Submitted That Met QC Criteria

February 2, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 5220098

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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