Experiences with using persuasive technology in a diet trial for older adults.

The PROMISS trial studies the effect of dietary advice to increasing protein intake on physical function in older adults with a relatively low protein intake, to promote healthy ageing. Part of this 6-months trial is the persuasive technology sub study, in which a tablet application using persuasive communication techniques and a specifically designed foodbox, both used for diet tracking, are provided to 48 participants. In this paper we present the results of our sub study for technology adherence, protein intake, experience of dietary advice and technology, and the effect of gamification on protein knowledge. Our results show that participants positively evaluate the tablet, but negatively evaluate the foodbox. The adherence of tablet users within the trial is high (on average 83% or 133 days), but there are no significant differences in the change of protein intake for our participants, compared to the 41 other participants in the intervention conditions of the trial. Based on these results we conclude that a diet tracking application designed for older adults is a feasible and appreciated tool to use within a dietary intervention study in older persons.