Influence of 2-Weeks Flavonoid Supplementation and an Acute 45-Minute Walking Bout or 2.5-h Running Bout on Plasma Levels of Gut-Derived Phenolics

Research Design: Study participants (N=85) will be entered into the study and randomized to the flavonoid or placebo supplement groups for 2 weeks, with these two independent groups run in parallel (with N=80 anticipated to successfully complete all study phases). Supplements will be administered in a double-blinded manner in capsule form. Study participants will report to the research facility for baseline testing and orientation, and then pre-study and after 2-weeks supplementation, and then again 24 hour later. Four blood samples will be collected as shown in the Figure (pre- and post-supplementation, post-exercise/rest, and 24-hour post-exercise/rest). When reporting to the lab after 2-weeks supplementation, study participants will be randomized to either sit or walk briskly on treadmills for 45 minutes. A comparator group of 20 runners ingesting the flavonoid supplement and running 2.5 h in the lab will be included to allow a comparison between moderate and intense exertion (and to provide pilot data for a future study). Baseline Testing: One to two weeks before the start of the study, study participants (walkers and runner) will be given an orientation to the study and then provide voluntary consent. Instructions will be given for recording all food and beverage intake in 3-day food logs (Thursday, Friday, and Saturday prior to starting supplementation). Demographic and training histories will be acquired with questionnaires. Height, body weight, and percent body fat (seca Medical Body Composition Analyzer 514 bioelectrical impedance scale, Hanover, MD) will be measured. VO2max will be assessed using the Bruce's treadmill protocol, with oxygen consumption and ventilation continuously monitored using the Cosmed CPET metabolic system.

Pre-Supplementation Lab Visit: On the first day of the study, participants (walkers and runners) will return to the lab in a fasted state (9 or more hours with no food or beverage other than water). Blood samples will be taken from an antecubital vein with subjects in the seated position. Participants (walkers) will be given a 2-week supply of flavonoid or placebo capsules organized into supplement trays to facilitate compliance. Runners will be given a 2-week supply of flavonoid capsules. The 3-day food record will be reviewed and collected by the research team, and analyzed for nutrient and flavonoid content using the Food Processor v. 11.1 (ESHA Research, Salem, OR). Each food/beverage will be assessed for macro- and micro-nutrients, total flavonoids and subtotals for each of the six flavonoid subclasses, and two individual flavonoid values (quercetin, EGCG). During the 2-day period prior to visit #3 to the lab, and during the entire day that includes visit #3, participants will be asked to avoid food and beverages containing sucralose (Splenda) and mannitol. To avoid sucralose and mannitol, participants will be asked to check ingredient lists for diet sodas, yogurt and other dairy products, snack foods, chewing gum and candy, low-sugar products, toothpaste, and mouthwash.

Post-Supplementation Lab Visits:

After the 2-week supplementation period, participants (walkers and runners) will return to the lab in an overnight fasted state (on the same day of the week as the pre-supplementation lab visit).

Participants will turn in the supplement tray to verify compliance with ingesting the capsules. A blood sample will be collected. Participants (walkers) will be randomized to either sit for 45 minutes in the lab or to walk briskly for 45 minutes on a 5% graded treadmill at 60% VO2max (with metabolic monitoring during the first 5 minutes, and then at 15, 30, and 45 minutes) using the Cosmed CPET metabolic cart. Runners will run at 70% VO2max on an ungraded treadmill for 2.5 h, with metabolic measurements made every 30 minutes. Water will be given ad libitum for all participants, with no other beverage or food allowed. Just prior to the sitting or walking lab sessions, and the 2.5 h run, participants will consume a 150-ml solution containing 1 g sucrose, 1 g lactulose, 0.5 g L-rhamnose, 1 g erythritol, 1 g sucralose, 0.5 g mannitol.