We live in a world of extremes in our politics and media. This lack of moderation is often displayed in our choice of health routines. "Experts" advocate dietary regimens in a mind-boggling array of vegetarian, gluten-free, dairy-free, and more unusual options, and we are bombarded by ads for medicines and dietary supplements. As a result, millions consume unregulated, untested products hoping for a magical cure. We also follow the latest trends in...