Two letters today challenge John Tierney’s excellent article “Public Policy Makes Test Subjects of Us All.” We responded that both letters miss the point. Susan Bagg suggests that “the American food industry might …be creating a sodium dependency” leading to obesity while Jerome Delamater accuses the food industry of "making test subjects of us all.” Both letters imply that the food industry is using more salt than previously and this is creating a health problem. But the supposition is just plain wrong. Salt intakes over the past century are unchanged and now evidence explains why: salt appetite is regulated by the brain, not by our taste buds, not even by our conscious choices and especially not by either the food industry nor NYC health chief Thomas Frieden. See “Salt Appetite” by the Salt Institute at http://www.saltinstitute.org/content/download/261/1495 . The point is: the human body requires salt; it’s an essential nutrient. And we have a built-in appetite to make sure we get it.