“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.”, Wall Street Journal
The Salt Libel
Another example that scientific debates are rarely ‘settled.’
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. Other than how to season tonight’s dinner, perhaps there’s a lesson here about politics and the scientific method.
The USDA, Food and Drug Administration and other regulators have long instructed eaters to consume no more sodium than 2,300 milligrams a day, or about a teaspoon, well below the U.S. average of 3,400 mgs. The limits are said to reduce the risks of high blood pressure, cardiovascular disease and stroke.
But several related papers in this week’s New England Journal of Medicine undermine these recommendations, and one even speculates that the official targets pose health hazards. In one of the most complete treatments of the subject to date, researchers followed more than 100,000 people world-wide for three and a half years. They found that those who consumed fewer than 3,000 mgs had a 27% higher risk of death or a serious medical event like a heart attack.
The findings are associations, not definitive clinical proof (to the extent there is such a thing). But they add to a growing literature arguing that the evidence that sodium is harmful is weak or nonexistent, including a report last year out of the Institute of Medicine.
If the war on salt was wrongly declared, that may be because diet is inevitably an elusive and ambiguous field given the complexity of human biology. What we know about the body evolves over time. Many theories of food and health are no more than superstition, so any nutrition advice that is more specific than moderation and more vegetables ought to be taken with a grain of—well, you know.
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. So be glad the salt debate continues.