Keeping your sodium intake as low as possible may not be so smart after all: Although the current Dietary Guidelines for Americans recommend limiting yourself to between 1,500 to 2,300 mg of sodium a day, there’s no proof that consuming less than 2,300 mg a day is actually beneficial—and in fact, it may even be harmful, according to a new report from the Institute of Medicine (IOM).
The federal guidelines were set back in 2005, after an earlier IOM report concluded that 1,500 mg of sodium was the lowest possible intake that allowed people to still get all of the other nutrients they needed—and that 2,300 mg of sodium was the maximum daily intake that didn’t negatively impact blood pressure. Based off of these findings, the federal guidelines suggested that those at risk for high blood pressure (people 51 or older, African Americans, and people with hypertension, diabetes, or chronic kidney disease—a group that, combined, makes up more than half the population) limit themselves to 1,500 mg of sodium a day. The guideline for everyone else was set at 2,300 mg. The American Heart Association actually took it a step further and recommended that everyone try to cap their daily sodium intake at 1,500 mg.
“Blood pressure is very important, but it’s important because it’s closely linked to heart attacks, to strokes, to heart disease, to kidney disease to lots of other problems—and to death,” says Brian Strom, MD, MPH professor of public health and preventive medicine and executive vice dean at the School of Medicine at the University of Pennsylvania. “In the interim years, new data have come out that studied those actual heart outcomes.”
So the CDC asked a committee from the IOM chaired by Strom to investigate how recent research has shown sodium intake to affect health outcomes like heart disease and death—rather than hypertension, an intermediate marker.
What they found: While lowering excessive salt intake can improve health outcomes, the committee didn’t find any evidence that health benefits are associated with lowering consumption to below 2,300 mg a day. This suggests that, while blood pressure is important, it’s not the only factor that affects health outcomes. What’s more, the committee found evidence that indicates going under this level—whether you’re at risk for high blood pressure or not—might lead to problems. Why? Likely because it’s difficult to get all of the other nutrients you need if you’re not taking in that much sodium, says Strom.
“You can’t change just sodium without changing your entire diet,” says Strom, pointing out that it’s extremely difficult to take in less than 1,500 mg of sodium a day; less than 1 percent of the population successfully limits themselves to this level.
“There are two studies that show benefit of going down to 2,300 mg, but there’s not one showing benefit going below that,” says Strom.
That said, the committee didn’t make any specific guideline recommendations. A different committee will take this report into consideration when assessing whether the federal guidelines should be updated; the next time the committee is scheduled to meet is in 2015.
The American Heart Association, meanwhile, is sticking to its recommendation of 1,500 mg of sodium a day or less, even in light of this new report.
“While the American Heart Association commends the IOM for taking on the challenging topic of sodium consumption, we disagree with key conclusions,” the association’s CEO Nancy Brown said in a statement.
Strom says that the IOM generally agrees with the American Heart Association, but that he hopes its leaders will reconsider their stance.
“The central point here is that people who eat diets that are too high in salt should lower it,” he says. “We don’t disagree with that at all—our only disagreement is that the target of 1,500 isn’t founded in science.”
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