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.