The Effects of Antioxidants in Blueberry Powder on Inflammation Induced by a Single High Fat Meal.

This study was designed as a single blind, placebo-controlled crossover study. Subjects were never told what dose of blueberry powder was given. Researchers handling samples and data did not know what dose of blueberry powder subjects received on test day 2 or 3. The frozen blueberry yogurt supplemented with either control or blueberry powder was coded by letter, and samples were coded by test day: since the control powder was given on the first day to all subjects, the laboratory staff analyzing the samples would have known that the first day samples were from the subjects receiving the control powder.The provision of the control powder on the first day to all subjects was done to mitigate potential carry over effects of the blueberry powder.The randomization plan for the two doses (two vs four servings) of blueberry powder was uploaded into a spreadsheet of which only the registered dietitian, the Human Studies Manager, and the Metabolic Kitchen and Human Feeding Laboratory staff had access. Subjects were instructed by a registered dietitian to follow a low polyphenol and omega-3 diet and limit consumption of fruits, vegetables, soy, fatty fish (e.g. salmon), whole grains, nuts, coffee, tea, and chocolate starting 3 days prior to each test day. The night before each test day, subjects were required to eat a standardized dinner provided by the WHNRC. Since a previous meal may impact the postprandial response of the next, subjects were fed a dinner that consisted of a burrito with tortilla, chicken, cheese, oil, and pinto beans as well as yogurt and lemonade. On each test day, subjects arrived at the WHNRC after a 12-hour overnight fast. Subjects had their body temperature, blood pressure, and weight measured, and then had blood withdrawn. Subjects were fed the MHF breakfast supplemented with a frozen yogurt containing either control or blueberry powder. Subjects were given 20 minutes to consume the entire breakfast. Subjects were instructed not to eat or drink anything other than plain water. Three and one-half hours following consumption of the test meal each subject returned to the WHNRC for a postprandial blood draw. Postprandial hypertriglyceridemia peaks on average 3.5 hours after the consumption of a high fat breakfast, thus the 3.5 hour blood draw provides the highest concentration of TGRL. Subjects were allowed to return to their normal activities after the morning meal before the postprandial blood draw. Following the postprandial blood draw, subjects were allowed to return to their normal dietary habits until three days prior to their next test day. Subjects were fed the control powder on their first test day. On the second and third test days subjects were fed varying amounts of the blueberry powder that were equivalent to two or four servings of fresh blueberries (24.1 g and 48.2 g of blueberry powder, respectively) in a random order.