It may seem counterintuitive, but a new study review suggests that consuming too little salt could be harmful to heart failure patients.

Doctors currently recommend a low-sodium diet to lower blood pressure and avoid fluid buildup and swelling, which can be common symptoms for heart failure. The condition develops when the heart muscle becomes too weak or stiff to effectively pump blood to the rest of the body.

But the new meta-analysis of nine randomized, controlled trials found that restricting dietary sodium intake below the standard recommended maximum of about 2.3 grams per day did not bring additional benefits, and it also may increase the risk of death.

The findings will be presented March 5 at the American College of Cardiology’s annual meeting, in New Orleans.

“Our findings showed that restricting dietary sodium to less than the usual recommendation was counterproductive in the management of heart failure,” said study lead author Dr. Anirudh Palicherla, an internal medicine resident at Creighton University School of Medicine in Omaha, Neb.

“Limiting sodium is still the way to go to help manage heart failure, but the amount of restriction has been up for debate,” Palicherla said in a meeting news release. “This study shows that the focus should be on establishing a safe level of sodium consumption, instead of overly restricting sodium.”

While the average American eats about 3.4 grams of sodium daily, U.S. Dietary Guidelines recommend limiting that to 2.3 grams daily or less. That’s a little less than 1 teaspoon of table salt.

The nine trials assessed different levels of sodium for a total of nearly 3,500 people with heart failure and included data on rates of death and hospitalization. Most of those trials were conducted between 2008 and 2022.

Researchers found that patients following a diet with a sodium intake target below 2.5 grams per day were 80% more likely to die than those following a diet with a target of 2.5 grams per day or more.

In the more restrictive studies, the sodium limits varied from 1.2 grams to 1.8 grams of sodium daily. Researchers did not find a trend toward increased hospitalizations among patients following more restrictive diets.

The designs of the clinical trials varied significantly, according to the study authors, including using different methods for tracking sodium intake. Some required participants restrict their fluid intake in addition to their sodium intake, while other studies did not.

The number of studies and total number of participants give the researchers a high level of confidence in the overall findings, even with these differences.

Future studies could help clarify the optimal targets for dietary sodium. They could also identify subgroups of heart failure patients who might benefit from more or less restriction, according to the authors.

People can limit their sodium intake by eating more fresh fruits and vegetables and cooking with basic ingredients rather than processed, boxed and canned foods and sauces. The researchers recommend asking for nutrition information or reading labels when eating out or buying prepared foods.

Findings presented at medical meetings are considered preliminary until published in a peer-reviewed journal.

More information

The U.S. National Heart, Lung and Blood Institute has more on heart failure.

SOURCE: American College of Cardiology, news release, Feb. 23, 2023