Acute improvement in the measure of executive function (DSST) and increased CBF in the right frontal gyrus during conscious resting state were observed 2h following consumption of 500ml of flavanone-rich citrus juice relative to a zero-flavonoid, vitamin C-matched, equienergetic CT drink. These data indicate that 70·5-mg flavonoids (specifically 42·15-mg hesperidin, 17·25-mg naringin, 6·75-mg narirutin, 4·3-mg caffeic acid) can increase CBF in healthy, young adults. However, these data do not provide evidence for a direct association between increased CBF and behavioural benefits. First, cognitive testing and CBF were not assessed simultaneously, and, moreover, no effects were observed for the majority of cognitive outcomes.