Effect of Blueberries on Immunity and Response to Flu Vaccination

Not Applicable

Active, not recruiting

• Conditions: Inflammation; Immune Response
• Interventions: Dietary Supplement: Blueberry powder group; Dietary Supplement: Placebo powder group

• Registration Number: NCT05534893
• Lead Sponsor: Loma Linda University

Brief Summary

This research study will test the effects of almonds on immune functions and immune response to influenza vaccine in overweight older men and postmenopausal women

Detailed Description

A free-living parallel, single-blind, RCT will be utilized. There will be two phases: Phase 1 - to examine the effects of Blueberries on plasma markers of immune strength, and Phase 2 - to assess the response to influenza vaccine following blueberry intake. Subjects will either consume their usual diet with (Blueberry group) or a placebo(control group) blueberries for 8 weeks, receive the influenza vaccination, and continue the intervention for another 4 weeks. The test food will be freeze-dried powder (FDP) (\~ to 1 cup fresh blueberries) per day with the usual diet. The control will be the placebo powder with some guidelines to restrict all berries and other polyphenol-rich foods. The entire study will last 12 weeks. Participants will attend a baseline clinic at which time they will be randomized to one of the two groups. Clinic visits will occur at baseline, weeks 4 and 8 before, and week 4 after vaccination.

Study Timeline

• Study First Submitted: 2022-09-06
• Study First Submitted QC: 2022-09-08
• Study First Posted: 2022-09-10
• Study Start: 2022-10-12
• Status Verified: 2025-03
• Last Update Submitted: 2025-03-06
• Last Update Posted: 2025-03-07
• Primary Completion: 2025-12
• Study Completion: 2025-12

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: All
• Target Recruitment: 52

Inclusion Criteria

• Older men and post-menopausal women aged 50-70 year 2. Have BMI of 25-32 3. Able to commute to Loma Linda University 3. Not taking medication or supplements that affect immunity 4. Agree to get vaccinated for Flu

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 less than 10 months ago from the start of the study

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Blueberry powder group	Blueberry powder group	Participants in the blueberry powder group will receive freeze dried blueberries in form of a powder
Blueberry powder group	Placebo powder group	Participants in the blueberry powder group will receive freeze dried blueberries in form of a powder
Placebo powder group	Blueberry powder group	Participants in the placebo group will receive an isocaloric placebo powder.
Placebo powder group	Placebo powder group	Participants in the placebo group will receive an isocaloric placebo powder.

Primary Outcome Measures

Name	Time	Method
changes in lymphocyte populations	baseline to 8 weeks	Immunophenotyping will be performed by flow cytometry to measure the number of T helper, T cytotoxic, Naïve and memory cells and B cells
changes in natural killer (NK) cell activity	baseline to 8 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
changes in complete blood count (CBC)	baseline to 8 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
changes in cytokine production	baseline to 8 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
changes in serum inflammatory cytokine concentration	baseline to 8 weeks	Changes in the concentrations of the inflammatory cytokines will be performed on serum using enzyme-linked immunoassay (ELISA)

Secondary Outcome Measures

Name	Time	Method
changes in neutralizing antibody titers against hemagglutinin and neuraminidase of the vaccine strain	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
changes in the viral load in response to vaccination	week 8 to week 12	viral load in blood will be measured using a quantitative polymerase chain reaction

Trial Locations

Locations (1)

Loma Linda University School of Public Health; 🇺🇸 Loma Linda, California, United States