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Completed

NCT Number: NCT05031663

Effect of Almonds on Immune Strength and Response to Flu Vaccination in Overweight Older Men and Postmenopausal Women: A Randomized Controlled Study

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

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Key information

Conditions

Immune Response Inflammation Pathologic Processes Pathological Conditions, Signs and Symptoms

Age range

40 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Loma Linda University School of Public Health

Loma Linda, California, 92350, United States

About this study

The proposed study is a parallel-group, free-living, observer-blind, randomized controlled dietary intervention trial on 66 overweight middle-aged men and post menopausal women. This study will be carried out in two phases: Phase 1 will examine the effects of almonds on clinically relevant markers of immune function, and Phase 2 will assess the antibody response to influenza vaccination following almond consumption. Participants will attend a baseline clinic and will be randomized to one of two groups. The Almond group will receive 15% of daily energy intake in the form of almonds as a snack and the Control group will continue thier usual diet but completely avoid almonds and restrict other nuts to less than 2 servings per week. The intervention will be for 12 weeks, at which time both group participants will receive the influenza vaccination, and continue the same dietary intervention for another 28 weeks.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Overweight men and post menopausal women (Basal Metabolic Index 25-32)
  • Age limit between 40-70 years
  • Be able to commute to Loma Linda University

Exclusion criteria

  • Intolerance or allergy to almonds
  • Bad dentures, inability to chew almonds
  • Regular intake of almonds and or other nuts
  • Use of immune boosting supplements
  • Exposure to antibiotics and corticosteroids immediately prior to study
  • Have received influenza vaccination in past 10 months
  • Uncontrolled chronic disease and psychiatric illness

Treatment and study plan

Almond group

Dietary Supplement

Participants in the Almond group will receive 15% of their daily energy intake in the form of almonds as a snack

Control group

Dietary Supplement

The control group will continue their usual diet but will completely avoid almonds and restrict other nuts to less than 2 servings per week

Primary outcomes

  1. 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

  2. changes in lymphocyte activity and 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

  3. 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

  4. 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)

  5. 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

Secondary outcomes

  1. changes in upper respiratory infection questionnaire score

    Time frame: baseline to 28 weeks

    Upper respiratory tract infections will be tracked using the Jackson and Dowling questionnaire. The questionnaire will be completed daily by participants, either manually or electronically , throughout the 28-week study period. The scale for the questionnaire is from 0-42. The higher score means worse outcome.

  2. changes in blood zinc levels

    Time frame: baseline to 12 weeks

    Zinc levels in blood will be analyzed in trace element- free tubes and assayed by atomic absorption spectrophotometry using standard reference material obtained from the National Institute of Standards and Technology to check the accuracy and precision of the determinations

Sponsors and collaborators

Lead sponsor

Loma Linda University

Other

Registry information

Official study title

Effect of Daily Consumption of Almonds on Immune Strength and Response to Flu Vaccination in Overweight Middle -Aged Men: A Randomized Controlled Study

Acronym: Almond Immune

Important dates

Study start
2021
Primary completion
2023
Study completion
2023
First posted
Sep 2, 2021
Registry last updated
Dec 9, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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