Mehmet Oz, a board-certified heart surgeon turned talk show host and lifestyle guru, is President-elect Donald Trump’s nominee to run the Centers for Medicare and Medicaid Services (CMS), the federal health care agency that covers more than a third of Americans. Although he made his reputation as a surgeon, he made his fortune as a salesman. He is perhaps best known for his TV show, Dr. Oz, on which he portrayed himself as a trusted doctor and dispensed nutritional and lifestyle advice, conveniently failing to make clear to his audience just how closely he worked with the companies he pitched. He repeatedly promoted products of questionable medical value and was named in lawsuits that alleged he made misleading claims on the show. Several of the companies he has promoted are structured as multilevel marketing businesses whose practices have repeatedly drawn the attention of federal regulators.