Benefit of low-salt diet for heart failure uncertain

Although many doctors advise heart failure patients to follow a low-salt diet to help minimize complications, a new study suggests there isn’t much high-quality evidence to support this recommendation.

“We still do not have a clear understanding of the mechanisms that may link salt intake with heart failure,” said lead study author Dr. Kamal Mahtani of the University of Oxford in the UK.

But the results still don’t mean doctors and patients should abandon recommendations to cut back on salt, said Dr. Clyde Yancy of the Northwestern University, Feinberg School of Medicine in Chicago.

“I am certain that there will be those who declare, 'Hallelujah! I can have a big bag of potato chips tonight!’ but don’t do it,” Yancy, author of an accompanying editorial, said by email. “The consequences will be the same as before, you will become ill.”

Restricting salt or sodium in the diet has been a cornerstone of lifestyle recommendations for heart failure patients, and that shouldn’t change because too much salt causes fluid retention that a heart weakened by heart failure can’t handle, Yancy said.

“The injudicious consumption of pizza, pickles, French fries and other very salted foods will lead to worsening heart failure, occasionally sufficient to require hospitalization,” Yancy said. “So yes, sodium restriction in heart failure remains necessary.”

But the study also highlights that scientists don’t know with certainty exactly what level of salt restriction is ideal or whether this might vary for different types of patients, Yancy added. More research is needed to answer this question and give patients better guidance in the future.

For the new study, Mahtani and colleagues examined data from nine previously published studies involving a total of 479 patients. None of these studies provided sufficient data to determine if a low-salt diet might be associated with a lower risk of death from cardiovascular causes like heart attacks or strokes.

“A lot of the guidelines appear to vary in the exact advice they give heart failure patients when it comes to reducing salt intake,” Mahtani said by email. “Our research highlights a paucity of robust high-quality evidence available to support or refute current guidance.”

High salt intake is a leading risk factor for high blood pressure, which can lead to heart disease, heart attacks and strokes.

Heart failure happens when the heart muscle is too weak to effectively pump enough blood through the body. Symptoms can include fatigue, weight gain from fluid retention, shortness of breath and coughing or wheezing. Medications can help strengthen the heart and minimize fluid buildup in the body.

Coronary artery disease, which develops when fatty deposits accumulate in the arteries and reduce blood flow, is a common cause of heart failure. Patients are often advised to cut back on salt to help lower their blood pressure and reduce the strain on clogged arteries.

In the study, researchers examined several potential impacts of a low-salt diet on heart failure patients and didn’t find a decisive connection.

For example, the number of repeat hospitalizations for acute illness was similar regardless of how much salt patients with heart failure consumed, the analysis found.

Salt intake also didn’t appear to influence the frequency or severity of heart failure symptoms.

One drawback of the analysis is that the smaller studies varied in how they measured salt intake and assessed heart failure symptoms and outcomes, making it hard to pool results across all of these studies to get a clearer picture of the impact of a low-salt diet, the authors note.