This research study will test the effects of Blueberries on immune functions in overweight older men and postmenopausal women
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
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
52
Participants in the blueberry powder group will receive freeze dried blueberries in form of a powder
Participants in the placebo powder group will receive an isocaloric placebo powder
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 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
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