Olive (Olea europaea L.) leaf polyphenols improve insulin sensitivity in middle-aged overweight men: a randomized, placebo-controlled, crossover trial - de Bock, M; Derraik, J G; Brennan, C M; Biggs, J B; Morgan, P E; Hodgkinson, S C; Hofman, P L; Cutfield, W S (PLoS One, 2013)