>Honest question: Why?
Why should an advertising company get access to this data in the first place? What do they intend on doing with it?
Selling us adverts based on a combination of our biochemical data, or the state of our health, coupled with our search terms that might indicate we have concern over one area or another?
Being able to help the medical sales industry target us more efficiently? As in "X user has Y indicators in their health data, therefore they would be a prudent market to advertise Z to"?