One in 20Google searches are for health-related information, giving the techbehemoth insight into things that we would neveradmit to a doctor.

Thanks to a combination of Google, WebMD and the $6,000 deductible on my health insurance, Ihaven't been to a doctor to talk about anillness in years. Millions of Americans have similar habits; infact, one in 20 Google searches are for health-related information.“Dr. Google” may not have an MD or a board certification, but itdoes have the clinical knowledge of a primary care provider whosees millions of patients a year.

With so much interest, it might be surprising how tentativelytech-driven efforts have entered the $3.5trillion health care industry. After three years, IBM's AI-drivenWatson for Oncology not only had not delivered new insights oncancer treatments, but also in some instanceseven recommended unsafe and incorrect treatments. In fairness toDr. Watson, it was working with the same scant medical records thatlimit human physicians. Artificial intelligence predictive capacitycomes not from superior processing power itself, but from usingthat processing power to discover signals in vast quantities ofdata.

Related: Amazon's latest venture: Mining your health caredata

Insights often arise in unexpected places. Some years ago,Target attracted attention for identifying a teenager's pregnancybefore the girl had informed her father. Turns out you can learn alot from a person's shopping history. A customer doesn't need to doanything as obvious as buying diapers or maternity clothes; thestore can make diagnoses based on subtle changes in shoppinghabits. Things like unscented lotions, vitamins and flu medicineall serve as leading indicators of an expectant mother. And aperson's shopping history is just one of millions of data pointscollected by ad platforms.

Ad networks like Google and Facebook track users all over the internet withcookies and device identifiers. They also work with data brokerslike Oracle's Datalogix, Acxiom and Experian, which aggregatepersonal data from public and private sources and sell access totheir partners. These online databases assemble informationcollected from store loyalty cards, public voting records, andsalary and pay stubs to form a comprehensive profile of everyindividual.

As a result, tech companies know things that we would neveradmit to a doctor. Amazon knows that I once treated a respiratoryinfection with fish amoxicillin (not that I'm recommending doingso); that I spray my yard with Roundup; and — thanks to thecompany's acquisition of Whole Foods — that I consume a lot of redmeat. Google has a history of every symptom I've ever typed into asearch bar and everywhere I've ever been, and can successfullydetect flu epidemics based on search queries. This data could helpGoogle to give better diagnoses: If I enter a list of earlysymptoms of Ebola on the WebMD Symptom Checker, it tells me I mighthave the stomach flu, but Google would have tracked me on a jungletrek in the Democratic Republic of the Congo and could predict thatI require something more than a bottle of Pepto-Bismol.

Tech companies that are accustomed to “moving fast and breakingthings” tend not to do well in a heavily regulated industry likehealth care. Pharmaceutical advertising is a multibillion-dollarbusiness, but digital ad networks have largely avoided it becauseof FDA concerns. Even a mobile app can be subject to regulatoryoversight if the FDA considers it a medical device. It's one reasonthat search engines play down their role in consumer healthcare.

IBM hastens to say that Watson is no substitute for oncologists,and Google is careful to point out that search results are notintended as medical advice. But the technology and the users havemoved ahead. Dr. Google is increasingly taking on the role ofprimary care providers.

This column does not necessarily reflect the opinion of theeditorial board or Bloomberg LP and its owners. To contact theeditor responsible for this story: Philip Gray [email protected] Elaine Ou([email protected]) is a Bloomberg Opinioncolumnist. She is a blockchain engineer at Global Financial Accessin San Francisco. Previously she was a lecturer in the electricaland information engineering department at the University ofSydney.