Study: Overstrict Salt Intake in Diet May Result in Common Form of Heart Failure

For the general public, low sodium intake can be associated with lower risk of cardiovascular disease. However, researchers found a worse prognosis for patients with heart failure with preserved ejection fraction (HFpEF) if their diets included little to no salt.¹

Doctors usually test ejection fraction to determine if the heart is functioning correctly.² Ejection fraction (EF) measures the percent of blood leaving the heart every time it contracts.² A normal EF ranges between 50 to 75%, according to the American Heart Association,but it does not always signify a healthy heart.² This phenomenon describes HFpEF, accounting for half of all heart failure cases.¹

Researchers analyzed data that had already been compiled from a phase 3, randomized, double-blind, placebo-controlled TOPCAT trial, which looked at spironolactone and HFpEF treatment. Researchers did a secondary analysis of this data to track 1713 individual’s salt intake over 3 years. All of the participants were aged 50 years or older and suffered from HFpEF.¹

During the trial, participants were asked the amount of salt they added to cooking staple foods, with results scored numerically at 0 points indicating no salt added, 1 indicating ⅛ teaspoon (tsp), 2 indicating ¼ tsp, and 3 indicating ½ or more of a tsp.¹

The primary endpoints in the study were death from cardiovascular disease, admittance to hospital due to heart failure, or resuscitation after cardiac arrest.¹ Secondary endpoints included death for any reason, hospital admission from heart failure, or death from cardiovascular disease.¹

Almost 816 patients scored 0, while the rest of the 897 patients had a score above 0. Not only were most of the 0-salt group White men, but results showed that they weighed significantly more, had lower diastolic blood pressure (70mm Hg) and greater hospital admittances, and were more likely to have type 2 diabetes, poorer kidney function, take meds, and lower cardiac output.¹

When assessing the rate of hospital admittance for heart failure, researchers concluded that participants under the age of 70 years would benefit from adding salt to their diet more than those older than age of 70.¹

“Overstrict dietary salt intake restriction could harm patients with [heart failure with preserved EF] and is associated with worse prognosis. Physicians should reconsider giving this advice to patients,” wrote the study authors.¹

This study was limited by observation and was not able to identify cause of the noted associations, explained the authors.¹ The trial is limited to participant self-reported scores, along with reverse causation of one’s original health. However, gender, heart failure medication use, and prior hospital admission for heart failure were not associated with cooking score or increased outcome risk.¹

References

1. Overly restrictive salt intake may worsen outcomes for common form of heart failure. BMJ; July 18, 2022. Accessed July 19, 2022.https://www.eurekalert.org/news-releases/958858#:~:text=Restricting%20salt%20intake%20is%20considered,online%20in%20the%20journal%20Heart.
2. Ejection fraction: What does it measure? Mayo Clinic; February 26, 2021. Accessed July 19, 2022. https://www.mayoclinic.org/tests-procedures/ekg/expert-answers/ejection-fraction/faq-20058286#:~:text=Ejection%20fraction%20is%20a%20measurement,The%20heart%20contracts%20and%20relaxes.
3. Heart failure with preserved ejection fraction (HFpEF): More than diastolic dysfunction. Mayo Clinic; May 20, 2015. Accessed July 19, 2022. https://www.mayoclinic.org/medical-professionals/cardiovascular-diseases/news/heart-failure-with-preserved-ejection-fraction-hfpef-more-than-diastolic-dysfunction/mac-20430055