[Healthy eating support groups on Facebook: content and features]

To determine the features and use of groups related to healthy eating on Facebook.

We carried out a cross-sectional study through the Internet. Using the API on Facebook, we included open groups related to healthy eating in the Spanish language. The variables studied were name, description, category, the number and gender of users, date of creation, number of posts, content of the first 20 posts, and the most recent update.

We selected 281 open groups for inclusion in the study. Of these, 125 were excluded because the content was unrelated to healthy eating. Finally 156 groups were studied with 14,619 users (10,373 women [71%] and 3,919 men [26.8%]). Dietary products were promoted by 40% of the groups.

Facebook is used as a means of communication and for sharing health information. Because many of these groups promote dietary products, their usefulness for health education is doubtful. Health organizations should participate in social media.