Lyophilized whole blueberries, purified blueberry extract, animal diets, and gavage doses were extracted and analyzed in triplicate, as described elsewhere (Furrer et al. 2017 (link)). Samples were resolubilized with 2% formic acid in water and purified via solid-phase extraction (SPE) using Oasis HLB 1cc extraction cartridges (Waters, Milford, MA, USA) (Furrer et al. 2017 (link)). All samples were analyzed for total and individual phenolics via the Folin method and UPLCMS/MS, respectively, as described previously (Song et al. 2013 ; Yousef et al. 2013 ; Yousef et al. 2014 ). The polyphenolic composition of the starting materials is shown in Table 1 .
To ensure the homogeneity of the test article and the consistency of the polyphenol content of the doses, each dose was analyzed every 10d throughout the study (data not shown). Because a single batch of purified blueberry polyphenols was homogenized prior to the study and used to prepare all doses, minimal differences were observed throughout the study. Blueberry polyphenol powder was kept frozen and dry until immediately prior to gavage administration, at which point, the powder was mixed with water to form a slurry. After administration, remaining gavage slurries were randomly tested to ensure test article stability and consistency throughout the experiment.
To ensure the homogeneity of the test article and the consistency of the polyphenol content of the doses, each dose was analyzed every 10d throughout the study (data not shown). Because a single batch of purified blueberry polyphenols was homogenized prior to the study and used to prepare all doses, minimal differences were observed throughout the study. Blueberry polyphenol powder was kept frozen and dry until immediately prior to gavage administration, at which point, the powder was mixed with water to form a slurry. After administration, remaining gavage slurries were randomly tested to ensure test article stability and consistency throughout the experiment.