We were told the science was settled. Yet new research suggests that salt is not nearly as dangerous as the government medical establishment has been proclaiming for many decades—and a low-salt diet may itself be risky.
Yet the latest USDA food pyramid, which was updated as recently as 2011, clings to simplistic low-salt pseudo-science. The FDA is pressuring food manufacturers and restaurants to remove salt from their recipes and menus, while the public health lobby is still urging the agency to go further and regulate NaCl as if it were a poison.
The larger point is that no scientific enterprise is static, and political claims that some line of inquiry is over and "settled" are usually good indications that real debate and uncertainty are aboil. In medicine in particular, the illusion that science can provide some objective answer that applies to everyone—how much salt to eat, how and how often to screen for cancer, even whom to treat with cholesterol-lowering drugs, and so on—is a special danger.
Government regulation often can lock in bad advice and practices and never changes as quickly as the evidence evolves.