The invention relates to a method for evaluating the effectiveness of an active ingredient selected from C7 avocado sugars, also called avocado perseose, for preventing or treating a deficiency of the skin barrier, said method comprising the determination of the level of expression and/or activation of at least one biological marker, where said biological marker is selected from epidermal maturation markers, lipid barrier markers, hydric regulation markers and stratum granulosum regulation markers.