Social media- and internet-based interventions are nowadays widely used tools in health interventions. Although evidence of their effectiveness is still low, their applications could be very promising due to their affordability and wide reach. The current paper aims to evaluate the effectiveness of an intervention program, "The University of Valladolid Community Eats Healthy" (UVEH), to increase fruit and vegetable (FV) intake in adults from the University of Valladolid (U. Valladolid) employing three online methodologies. A sample of 211 volunteers was randomly assigned into four groups: virtual campus (VC), Facebook (FB), Instagram (IG), and control. An intervention based on the Theory of Planned Behavior was implemented for seven weeks. Data were collected at the beginning (T0) and the end of the program (T1). The Predimed questionnaire was employed to assess FV intake. Vegetable intake was statistically significantly higher in the VC group (17.4% pre vs. 72.7% post). In the rest of the groups, there was also an increase in intake. Fruit consumption increased slightly only in the VC group (23.9% pre vs. 45.5% post). Participation decreased through the weeks: FB (week 2), IG (week 3), and VC (week 4). Retention was higher in the VC (48%) and control (60%) groups. Internet-based interventions employing interactive platforms such as virtual campus can be effective in enhancing participants' dietary habits in a clinically relevant manner.
Keywords: Facebook; Instagram; behavioral theory; fruit; intervention; nutrition education; social media; university; vegetable; virtual campus.