Apple is taking steps toward ensuring it has the trust of its users in the mobile health arena. The first of these steps is to ensure that user data is kept away from advertisers and data brokers.

The HealthKit platform update will stop third-party apps from doing anything with user data collected by the Health app, such as selling it to advertisers. The one thing that third-party apps will be able to do is update users about their health.

"You and your application may not use the HealthKit APIs, or any information obtained through the HealthKit APIs, for any purpose other than providing health and/or fitness services in connection with your application (e.g., not for serving advertising)," Apple states in the update. The Health app acts as a dashboard and collects data on blood pressure, heart rate, and stats on diet and exercise, while HealthKit health and fitness apps can use that data to help make your health better.

For example, a developer who creates an app related to high blood pressure could not pass on information about a user to a company who might want to sell that user blood pressure medication.

"Developers must not sell an end-user's health information collected through the HealthKit APIs to advertising platforms, data brokers or information resellers," said the update. As long as developers get users' consent first, they will be able to pass on data to medical researchers.

HealthKit was first announced at WWDC this year, and it aims to be the central hub for user data related to health. It will hopefully be able to collect information from third-party apps, and display that information in an easy-to-understand manner.

Apple has even partnered with health care providers such as the Cleveland Clinic and Johns Hopkins, among others.

The move to update the privacy policy is a step forward for Apple toward ensuring that users trust them, which is especially important when it comes to issues like health. This may also give Apple an edge over companies like Google that aim to monetize the data that it is given through advertising.

More details about the HealthKit app are expected to be unveiled soon, including a list of partners, one of whom is expected to be Nike.

The update of the HealthKit app's privacy policy came ahead of an Apple press event set for Sept. 9, for which invitations were sent out on Thursday. The event is expected to include the release of the iPhone 6, as well as the long-awaited iWatch. Two iPhone models are expected to make their debut at the event, one with a 4.7-inch display, and one with a larger 5.5-inch display.

Apple is also set to release its next version of iOS, its mobile operating system, which will be called iOS 8.