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
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
61
Participants in the Almond group will receive 15% of their daily energy intake in the form of almonds as a snack
The control group will continue their usual diet but will completely avoid almonds and restrict other nuts to less than 2 servings per week
Loma Linda University School of Public Health
Loma Linda, California, United States
changes in lymphocyte populations
Immunophenotyping will be performed by flow cytometry to measure the number of T helper, T cytotoxic, Naïve and memory cells and B cells
Time frame: baseline to 12 weeks
changes in lymphocyte activity and cytokine production
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
Time frame: baseline to 12 weeks
changes in natural killer (NK) cell activity
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
Time frame: baseline to 12 weeks
changes in serum inflammatory cytokine concentration
Changes in the concentrations of the inflammatory cytokines will be performed on serum using enzyme-linked immunoassay (ELISA)
Time frame: baseline to 12 weeks
changes in complete blood count (CBC)
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
Time frame: baseline to 12 weeks
changes in upper respiratory infection questionnaire score
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.
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Time frame: baseline to 28 weeks
changes in blood zinc levels
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
Time frame: baseline to 12 weeks