Satiety in rats following blueberry extract consumption induced by appetite-suppressing mechanisms unrelated to in vitro or in vivo antioxidant capacity

Water extracts of two blueberry cultivars ('Centurion' and 'Maru') were tested for their ability to modify appetite in a rat model. The fruits of 'Centurion' had higher in vitro antioxidant capacity (as measured using the ferric reducing antioxidant power (FRAP) assay) and higher total phenolic content (TPC, as measured by the Folin-Ciocalteu method) than fruits of 'Maru'. When rats were gavaged with water-soluble blueberry extract (BBE; 1 ml/day) of both cultivars for 6 days, serum FRAP increased significantly when compared to water-gavaged controls, indicating that BBE may have the ability to elevate circulating antioxidant potentials in vivo. Both cultivars had a satiating influence on experimental rats, as evidenced by their ability to decrease food intake by 8.6% ('Maru') and 6.2% ('Centurion'), although a statistically significant decrease over the control rats was achieved only for the 'Maru' treatments. In addition, body weight gain of rats gavaged with extracts from 'Maru' and 'Centurion' cultivars decreased by 9.2% and 5.3% relative to the rats in the control group, respectively. The reduction in food intake over a 4 h period compared to a control treatment preloaded with the same volume of water suggests that the decrease in food intake was mainly a consequence of a satiating effect, rather than a stomach distension effect. The observed results suggest that the reduction in food intake and decrease in body weight in experimental animals is not merely a consequence of antioxidant mechanisms. BBE may provide a good satiety inducer and weight management modulator.