There are now more than 250,000 apps available for the iPhone, more than 30,000 such apps for smartphones running Android, and several thousand for those who have Blackberry devices.

There are apps for counting calories and nutrition information; apps for logging fitness workouts; apps to monitor vital signs; apps providing health tips; apps to calculate disease risks; apps to calculate body mass index; apps for keeping personal health records and for providing users’ health information to physicians and emergency workers; apps to learn about medicines; apps for smoking cessation; and apps for yoga stretching exercises people can perform at their desks at work.

Cell phone users between 18-29 years old are more likely than older cell owners to use mobile health apps: 15% do so, compared with 8% of cell users ages 30-49, for example. African American cell phone owners are more likely than other groups to use such apps: 15% do so, compared with 7% of white and 11% of Latino cell phone users. Urban cell phone owners are more likely than those who live in suburban or rural areas to have a mobile health app on their phone. There are no significant differences between men and women, nor among income groups.