While sports nutritionists have since come around to recommend that we should replenish salt when we sweat it out in physical activity, the message that we should avoid salt at all other times remains strong. Experts say salt raises blood pressure, causes hypertension, and increases the risk of premature death. This is why the Department of Agriculture’s dietary guidelines still consider salt Public Enemy No. 1, before fats, sugar, and alcohol. It’s why the director of the Centers for Disease Control and Prevention has suggested that reducing salt consumption is as critical to long-term health as quitting cigarettes. And yet, this eat-less-salt argument is surprisingly controversial—because the actual evidence to support it has always been so weak.