Millions of Americans have heart failure, a condition in which the heart can no longer pump blood efficiently. This is not a heart attack, though once someone has a heart attack, she may be more susceptible to heart failure. Here are just a few people who have died from heart failure: Elizabeth Taylor, Salvador Dali, Danny Thomas, George Carlin and Marlon Brando. One of the most fundamental recommendations for treating this potentially deadly disorder: salt restriction for heart failure. Is it justified?

Doctors Question the Validity of Salt Restriction for Heart Failure

Physicians are admonished to practice “evidence-based medicine.” Most are convinced that they are doing just that. It means that they rely on high-quality research to make decisions about treatment. But something as fundamental as salt restriction for heart failure is surprisingly short on science.

We are always impressed when physicians admit that there is a lack of evidence for a highly recommended practice. A recent review of research on the benefits of this practice revealed surprisingly little evidence to support the recommendation of salt restriction for heart failure (JAMA Internal Medicine, online Nov. 5, 2018).

Out of 2500 studies on heart failure, only 9 were randomized controlled trials looking at how sodium intake affects outcomes. Restricting sodium did not make an obvious difference in heart attacks, strokes or death.

The authors introduce their review this way:

“Despite advances in diagnosis and management, the prevalence of heart failure is increasing. Recent estimates suggest that more than 26 million people are affected worldwide, including inpatients and outpatients…

“Advice to reduce salt intake is recommended in several international cardiovascular guidelines.”

“However, restriction of salt intake has uncertain efficacy. Observational studies have shown potential benefits and harms, whereas some randomized clinical trials (RCTs) have suggested harms. A previous systematic review and meta-analysis concluded that a low-salt diet, compared with normal salt intake, significantly increased morbidity and mortality in individuals with heart failure.”

The authors conclude:

“To our knowledge, this systematic review represents the most up-to-date and comprehensive analysis of current evidence of the effects of reduced salt intake in patients with heart failure. Despite identifying 9 RCTs involving a total of 479 participants, we found no robust high-quality evidence.

“We found no clinically relevant data on whether reduced dietary salt intake affected outcomes such as cardiovascular-associated or all-cause mortality, cardiovascular-associated events, hospitalization, or length of hospital stay.”

What to Make of Salt Restriction for Heart Failure?

For something that is so ingrained in medical practice it is hard to believe that there is inadequate evidence to support the recommendation. It is entirely possible that salt restriction for heart failure makes sense. It is equally possible that it is harmful.

An accompanying editorial in JAMA Internal Medicine notes:

“It is incredulous that in our evidence-based era, we have accepted such a low bar for this particular bedrock recommendation of cardiovascular care.

“…A practical solution might be a shift away from sodium restriction per se and more toward a DASH (Dietary Approaches to Stop Hypertension)-like diet in heart failure.

The physician who wrote the editorial cautions his colleagues:

“Before we persist with unyielding recommendations for aggressive sodium restriction at significant costs for uncertain benefits and unknown harm, do the trials.”

In other words, let’s have some evidence! We could not agree more.

JAMA Internal Medicine, online Nov. 5, 2018

Editorial in JAMA Internal Medicine, online Nov. 5, 2018

Are you surprised that the evidence for salt restriction for heart failure is woefully inadequate? Share your thoughts in the comment section below.

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