The Danger of Low Sodium Diets

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We’ve been told for decades to watch our salt consumption in order to keep blood pressure in check and heart disease risk low. Both the American Heart Association and the latest federal dietary guidelines advise limiting intake to 2.3 grams a day. But if you don’t already have hypertension, will staying below that number actually benefit you? There isn’t much evidence to show that it will. In fact, a new study links lower salt intake to higher blood pressure and heart disease risk, versus the other way around.

Researchers at Boston University School of Medicine tracked the sodium intakes and blood pressure of more than 2,600 adults ages 30 to 64 over 16 years. Everyone had normal blood pressure at the study’s start, but by the end, several people had developed hypertension. However, those who kept their sodium intake below 2.5 grams a day actually had higher blood pressure on average than the people who consumed more salt.

“People with higher sodium intakes, but also higher intakes of potassium, had lower blood pressure and the lowest risk of heart disease,” says lead researcher Lynn Moore. “It’s hard to tell whether higher sodium intakes are beneficial, but for generally healthy people, we saw no evidence of harm in consuming the average American intake of 3.6 grams a day.”

Why, then, is there so much concern around salt? “We know that if people who have high blood pressure reduce their salt intake, their blood pressure can go down,” Moore says. “But this led to the assumption that if generally healthy people just reduce sodium intake, they’ll automatically have lower risk of hypertension and heart disease. That was a big leap, and it’s not always true.”

Moore points out that people with high blood pressure are often salt sensitive, meaning their blood pressure fluctuates more dramatically in response to salt. That’s why these folks really can benefit from laying off the salt. But if you’re not salt sensitive, slashing intake may not do you much good. It could even be detrimental.

“Studies have shown that a low-sodium diet can raise cholesterol and triglycerides,” Moore says. “It can also have an adverse effect on the renin angiotensin aldosterone system, a pathway to high blood pressure. Restricting salt really turns that system on, activating the sympathetic nervous system and potentially increasing risk of heart disease.”

While you shouldn’t obsess over salt, everyone should still keep an eye on their intake, says Moore, since hitting 5 or 6 grams a day can elevate cardiovascular risks. But also make sure to get plenty of potassium, magnesium, and calcium, which interact with sodium to influence fluid retention and blood pressure. “Our study, along with past evidence, shows these minerals have a beneficial effect on blood pressure and heart disease risk,” Moore says. “You can even manage salt sensitivity by increasing intake through fruits, vegetables, and dairy.”