In a report that undercuts years of public health warnings, a prestigious group convened by the US government says there is no good reason based on health outcomes for many Americans to drive their sodium consumption down to the very low levels recommended in national dietary guidelines.
Those levels, 1,500 milligrams of sodium a day, or a little more than half a teaspoon of salt, were supposed to prevent heart attacks and strokes in people at risk, including anyone older than 50, blacks and people with high blood pressure, diabetes or chronic kidney disease.
But the new expert committee, commissioned by the Institute of Medicine, said there was no rationale to aim for sodium levels below 2,300 milligrams a day. The group examined new evidence that had emerged since the last such report was issued, in 2005.
"As you go below the 2,300 mark, there is an absence of data in terms of benefit and there begin to be suggestions in subgroup populations about potential harms," said Dr Brian L Strom, chairman of the committee and a professor of public health at the University of Pennsylvania.
He explained that possible harm included increased rates of heart attacks and an increased risk of death.
The committee was not asked to specify an optimal amount of sodium and did not make recommendations about how much people should consume.
Strom said people should not eat too much salt, but he also said that the data on the health effects of sodium were too inconsistent for the committee to say what the upper limit of sodium should be.
There are physiological consequences of consuming little sodium, said Dr Michael H Alderman, a dietary sodium expert at Albert Einstein College of Medicine who was not a member of the committee.
As sodium levels plunge, triglyceride levels increase, insulin resistance increases, and the activity of the sympathetic nervous system increases. Each of these factors can increase the risk of heart disease.