Walnut and Immunity Study

Not Applicable

Completed

• Conditions: Upper Respiratory Tract Infection; Immune Response
• Interventions: Dietary Supplement: walnuts; Dietary Supplement: Habitual diet

• Registration Number: NCT05915390
• Lead Sponsor: Loma Linda University

Brief Summary

The main objective of the study is to determine if eating walnuts enhances immune function, in older free-living men and postmenopausal women with overweight.

Detailed Description

The main objectives of our proposed study are to determine the effect of walnut consumption on innate, acquired, and gut immunity by assessing whether the ingestion of walnuts enhances immune function, in older free-living men and postmenopausal women with overweight. To accomplish these objectives, a randomized controlled, parallel design study is proposed with two groups consuming their habitual diet, but with one (Walnut group) receiving 15% of their total energy as walnuts and the other (Control group) abstaining from eating any walnuts and limited amounts of other tree nuts and peanuts (up to \<1 serving/wk).

Study Timeline

• Study First Submitted: 2023-05-16
• Study First Submitted QC: 2023-06-21
• Study First Posted: 2023-06-23
• Study Start: 2023-06-27
• Primary Completion: 2023-12-18
• Study Completion: 2023-12-18
• Status Verified: 2024-09
• Last Update Submitted: 2024-09-30
• Last Update Posted: 2024-10-02

Recruitment & Eligibility

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

Inclusion Criteria

• Older men and post-menopausal women aged 55-75 years
• Have a BMI of 25-32
• Being able to commute to Loma Linda University.
• Not taking medication or supplements that affect immunity

Exclusion Criteria

• Intolerance or allergy to walnuts
• Regular intake of walnuts and/or other nuts (>3 ounces per week).
• Immune system insufficiency or disease.
• Using immune boosting supplements.
• Exposure to antibiotics and corticoids immediately prior to the study.
• Participants with uncontrolled chronic diseases, and relevant psychiatric illness, including major depression will not be included in study
• Flu vaccination or Covid booster within past 6 months

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
walnut group	walnuts	walnut group will receive 15% of their total energy as walnuts
control group	Habitual diet	continue with habitual diet and abstain from eating walnuts

Primary Outcome Measures

Name	Time	Method
changes in lymphocyte activity	baseline to 12 weeks	The production of lymphocytes will be measured in the supernatant using Enzyme linked immunosorbent assay (ELISA)
changes in cytokine production	baseline to 12 weeks	The cytokines produced due to lymphocyte activity will be measured in the supernatant using Enzyme linked immunosorbent assay (ELISA)
changes in serum inflammatory cytokine concentration	baseline to 12 weeks	changes in the concentrations of the inflammatory cytokines will be performed on serum using enzyme-linked immunoassay (ELISA) will include hs-CRP, interleukin (IL)-1β, IL-6, TNF-α, IL-10, and IL-4.
changes in diversity of immune-modulating and butyrate -producing gut bacteria in feces	baseline to 12 weeks	DNA extraction from stool samples will be performed using QIAamp DNA Stool Mini kits.69 The QIIME (Quantitative Insights Into Microbial Ecology) software will be used to analyze 16S rRNA gene sequences and determine the effect of the intervention on microbial diversity at the phylum, genus, and operational taxonomic unit levels.
Changes in concentration of Immunoglobulin A in feces	baseline to 12 weeks	changes in Immunoglobulin A will be determined using high performance liquid chromatography-mass spectrometry (HPLC-MS)
changes in lymphocyte populations	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
Changes in concentration of Calprotectin in feces	baseline to 12 weeks	changes in Calprotectin will be determined using high performance liquid chromatography-mass spectrometry (HPLC-MS)
Changes in concentration of small chain fatty in feces	baseline to 12 weeks	changes in Small chain fatty acids will be determined using high performance liquid chromatography-mass spectrometry (HPLC-MS)

Secondary Outcome Measures

Name	Time	Method
changes in upper respiratory infection questionnaire score	baseline to 12 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 12-week study period. The scale for the questionnaire is from 0-42. The higher score means worse outcome.

Trial Locations

Locations (1)

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