Google philosophy: Focus on the user and all else will follow.
Match content, products, services and site navigation to well-researched consumer interests and Internet search trends. This will increase the relevancy of the site, increase the potential reach of the site (market share), and help search engines recognize the site as a great resource for content, products and services related to the web site and popular Internet search terms.
The below article from U.S. News & World Report suggests that health web sites should focus on providing content, products, services and site navigation based upon the following topics:
Then, of course, add the site's own specialized content areas into the navigation and content categories.