The Acute and Chronic Effects of Fruit Polyphenols on Chronic Disease (PPF)

Overview

1. The primary objective is to determine the effect of fruit polyphenols on postprandial lipoprotein triglyceride metabolism after consumption a standard high carbohydrate/fat breakfast meal with a beverage rich in fruit-derived polyphenols compared to energy and macro-/micro-nutrient matched control beverage (acute, Part 1). 2. Secondary objectives are: 1)to assess the effects of consuming daily for 8 weeks (chronic, Part 2) a beverage rich in fruit polyphenols compared to an energy and macro-/micro- nutrient matched control beverage on fasting glucose, insulin, lipids and markers of oxidative stress; and 2) to assess the effects of these beverages on meal-related changes in metabolic and oxidative stress measures after 8 weeks daily consumption.

The study is a single-center, double-blinded, randomized, 2-part, 2-arm, 4-sequence, crossover study that incorporates both the acute and chronic evaluations of fruit polyphenols on metabolic indices and markers of oxidative stress. A planned sample size of 30 overweight men and women will be recruited into the study. Subjects will be required to meet several inclusion and exclusion criteria, which will be assessed through online and clinic screening mechanisms, including questionnaires, blood analysis, and anthropometric measurements. Eligible subjects will be invited to participate in the study. Subjects will begin by completing a 7-day pre-study assessment of their usual dietary intake using 3-day food diary followed by washout of dietary polyphenols. Subjects will participate in 4, 6 h postprandial study days: 2 preceding the chronic intervention and 2 after 8 weeks each of active (fruit polyphenols) and placebo beverages. Subjects will be randomized on the first day of starting the acute and chronic study phases. Subjects will be asked to limit polyphenolic containing foods and beverages for 3 days prior to each 6 h postprandial study visit as well through the chronic dietary intervention. Subjects will be provided a standardized dinner meal pack on the day before each 6 h postprandial visit. For each 6 h postprandial study visit, subjects will arrive fasted and follow procedures published by our lab previously. This includes: pre-study evaluation for compliance (fasting, dinner consumption, limited polyphenol intake) and readiness for study visit, catheter placement by registered nurse, fasting blood sample, consumption of high fat/carbohydrate meal accompanied by 1 of the two treatment beverages (active/fruit polyphenol or placebo beverage), subsequent blood sampling from catheter \[ \~1 tablespoon (12ml)\] at designated time points for 6 hours. Each postprandial study visit day will last approximately 7 hours and subjects will be required to remain at the Clinical Nutrition Research Center at the Illinois Institute of Technology main campus for the duration of the visit. The visit procedures are repeated twice \~ 1 week apart to accommodate subject testing with both beverages. After completing both acute 6 h postprandial study visits, subjects will roll over to the chronic phase of the study and receive a 2nd randomization sequence for consuming the active or the placebo beverage daily for 8 weeks. Before crossing over to the alternative treatment beverage for another 8 weeks, subjects will have a 4-week break (wash out). Subjects will be counseled for a low polyphenolic diet throughout the study to consume the assigned beverage twice per day with lunch and evening meals (except during 4-week washout). At the end of each week 8 treatment period, subjects will come to the research center for a 6 h postprandial study visit day: all procedures are identical on each postprandial study test visit with the exception that only the placebo beverage will be consumed with the breakfast.