METHODOLOGY/EXPERIMENTAL DESIGN-CROSSOVER
We plan to test the effects of feeding grapes (using the supplied freeze-dried grape powder from the California Table Grape Commission) in subjects aged 18 years of age or older. This study will be done in a free-living population, using a double-blinded randomized clinical trial (RCT) crossover study design at California Polytechnic University, Pomona
There will be a 3-month recruitment and screening period in which approximately 60 persons will be screened. There will be two 8-week randomized diet periods (to either Group A or B) separated by a washout period. Subjects will follow each of the randomly assigned diets: Freeze-Dried Grapes (Experimental/Treatment) for 8 weeks or Freeze-Dried Control (supplied by California Table Grape Commission), once a day for 8 weeks. The control diet-consumed during one of the treatment arm periods-will consist of the person's normal (habitual) diet with the absence of grapes in any form (including alcohol) and a grape-look alike placebo. The experimental diet will consist of the normal (habitual) diet of each subject, with the addition of the freeze-dried grapes in a 6 oz glass of water per day and the absence of grapes in any form. There will be a 5-8 week washout period between the two treatments.
Blood drawings, BP, hs-CRP and TNF-alpha, and body composition measurements will be performed on each subject at week 0, and after 8 weeks of each period arms. A phlebotomist at the California Polytechnic University, Pomona (CPP) Student Health Center, will draw the blood samples. An independent laboratory will analyze the coded blood samples for triglycerides, glucose, hs-CRP and TNF-alpha, total blood cholesterol, LDL, and HDL cholesterol levels.
Body composition will be measured using a Tanita Bioimpedance scale (T-310) and blood pressure will be taken with the OMRON blood pressure monitor.
As well, three 24-hour randomized diet recalls will be administered during each treatment to obtain information regarding the subject's diet and adherence to the diet protocol, and ESHA Research Food Processor will be used to analyze the diet. Adherence to the assigned diets will be assessed using an Unusual Diet Diary, which is filled out by the participant when unusual quantities of foods or accidental grape consumption occurs, medical treatment is required, pharmaceuticals/antioxidant supplements are consumed, or the participant exercises to excess. Visual Analog Questionnaires will be used to determine satiety and hunger during both study periods the day after the diet recall is obtained.
Subjects will pick up their study material allotment every week from the PI's office which is in room #119 in the Don B. Huntley College of Agriculture at Cal Poly Pomona. After Informed Consent is obtained, subjects will be instructed on how to mix the freeze-dried powder into the water as per the California Table Grape protocol.
Timetable The study timeline is 1 year, (includes subject recruitment, the study duration, laboratory analyses, and 2-3 months to organize and analyze the data, provide a report to the funders, and publish the results). The study, after obtaining participants, will commence at the beginning of August 2023, and end July 31, 2024. The two Co-PIs, two graduate students and 4 undergraduate students will conduct this study. The undergraduate students will help in recruitment and retention as well as performing, input and analysis of the 24-hour recalls in the ESHA software, Tanita measurements, passing out the subject's allocations, and tabulating the questionnaires.
