We've all heard the advice to go easy on the salt shaker. Or, perhaps, more importantly, to cut back on eating packaged, processed foods that often contain a lot of salt.
And why? There's a lot of evidence linking excessive sodium intake to high blood pressure, which increases the risk of heart disease.
The dietary guidelines recommend that adults consume no more than 2,300 milligrams of sodium per day.
But a new study suggests that when it comes to the optimal amount of salt in our diets, there may be more leeway than we thought. At least for some of us.
The new meta-analysis, published in the American Journal of Hypertension, concludes that both low-sodium and high-sodium intakes are associated with increased risk of death. The analysis is based on pooled results of about 25 prior studies.
The study authors also argue that consuming anywhere from about 2,600 milligrams up to almost 5,000 milligrams of sodium per day is associated with more favorable health outcomes (compared with lower or higher consumption.) In other words, the range of what's healthy is a lot broader than what the U.S. government's guidelines advise, the researchers say.
"I think an [upper] limit of about 4,700 milligrams would be more reasonable," lead author Niels Graudal of Copenhagen University Hospital told us by email. And this is far higher than the average consumption of Americans, which hovers in the range of 3,400 milligrams per day.
Graudal agrees with the overwhelming evidence that lowering sodium can help people with hypertension, or chronically high blood pressure, lower their blood pressure. (There's a genetic component to being at risk of high blood pressure, so not everybody's risks are the same.)
But, he argues, in people with normal blood pressure, "there is no effect, or maybe a small effect of sodium reduction on blood pressure."
"The good news," Graudal writes in a press release about the study, "is that around 95 percent of the global population already consumes within the range we've found to generate the least instances of mortality and cardiovascular disease."
Now, these findings are controversial. And some public health experts say Graudal's findings are way off base.
"There is no credible evidence that a low-sodium intake, in the recommended range, is harmful," Lawrence Appel, who directs the Welch Center for Prevention, Epidemiology, and Clinical Research at Johns Hopkins Medical Institutions, told us in an email.
"This paper is a diversion from the main public health issue: namely, controlling blood pressure — the leading preventable cause of mortality worldwide," says Appel.
He points to a recent, long-term study that finds a direct relationship between sodium intake and cardiovascular disease.
And an analysis we reported on from the Centers for Disease Control and Prevention data backs up these findings. Even among children, higher sodium leads to higher blood pressure, that study found.
Appel says the bottom line is this: In order to improve heart health, we have to improve blood pressure control. And "lowering sodium intake is key to achieving this goal."