Too much salt causes high blood pressure, right? Well, yes and no.

“The more salt you eat, the higher your blood pressure will be.” –Blood Pressure UK. 

“In some people, sodium can increase blood pressure.” –The American Heart Association. 

“You need to find out where you are on the salt spectrum,” said Robin A. Felder, Ph.D., a professor of pathology and associate director of laboratory medicine at the University of Virginia. “Everybody is different. One size does not fit all.”

The truth is murky. But don’t treat the ambiguity as an excuse to indulge in pizza and salty snacks.

Clearly, consuming too much salt carries at least some risk. Salt forces the body to retain water. Excessive salt causes extra water to flow into your blood, creating more pressure on your blood vessels.

But that doesn’t mean your blood pressure will always soar along with your salt intake. In a 2022 research paper, Felder and his co-authors found what they call “inverse salt sensitivity” in roughly 15% of the subjects in a randomized study. For these individuals, their blood pressure went down while consuming a relatively high salt intake.

Still, Felder isn’t urging everyone to load up on salt. About 20% of the subjects were salt-sensitive: As they ate more salt, their blood pressure increased.

“The best thing you can do is avoid restaurant meals,” Felder said. He adds that lunch sandwiches (consisting of most types of bread, cheese and deli meats) deliver a heavy dose of salt that often exceeds the CDC’s recommendation of less than 2,300 milligrams per day.

To add to the confusion, there’s an often-overlooked difference between an immediate spike in blood pressure that salt might cause and its potential long-term effects.

“It’s true that some people seem to have a bigger increase in blood pressure when they have a salty meal,” said J. Brian Byrd, M.D., an assistant professor and cardiologist at Michigan Medicine Frankel Cardiovascular Center. “In short-term studies, less salt intake has an impact on blood pressure. But it’s hard to know the long-term impact of salt intake on blood pressure.”

There’s some uncertainty among researchers on how to conduct long-term studies that examine the link between salt consumption and blood pressure.

“I’ve seen some radical ideas, like studying it in prisons,” Byrd said. But collecting reliable data over the long term remains a challenge.

There’s no doubt that high blood pressure (hypertension) is a leading cause of death globally. It can cause cardiovascular diseases such as heart attacks and strokes. Nearly half of American adults—about 120 million—have hypertension (generally defined as blood pressure readings above 130/80). 

Byrd warns that it’s not enough to avoid the saltshaker at meals. Even if you never reach for it, you may still exceed the daily 2,300 mg suggested limit. Americans on average consume more than 3,400 mg of sodium a day.

Aside from the obvious culprits such as processed foods, soups and ravioli, there are less well-known, salt-heavy foods.

“The No. 1 source of sodium in the U.S. diet is bread,” Byrd said. “That’s a surprise to many people. And many chicken breasts are injected with salt, especially chicken served in restaurants.”

Like Felder, Byrd is wary of the high amount of salt found in many restaurant meals. In the absence of nutrition labels, you can only guess at how much salt you’re eating when dining out.

If you buy rotisserie chicken at the supermarket (or at Costco for the disturbingly low price of $4.99), a single serving of four ounces can represent one-quarter or more of the recommended daily sodium limit.

Byrd, an expert on hypertension, acknowledges that it’s possible that for some people, consuming too much salt won’t necessarily cause prolonged, elevated blood pressure.

“But there’s no way to know if you’re not salt-sensitive,” he said.