Sodium Restriction in Patients with Heart Failure Does Not Reduce Mortality, Morbidity

Restricting sodium intake in patients with heart failure (HF) does not reduce morbidity or mortality, despite the widely held belief that doing so improves the outcomes of these patients, according to a narrative review published in Wiley.¹

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For decades, restricting sodium intake has been promoted to reduce edema and complications that follow HF. Associations between sodium intake and blood pressure control, as well as the connection between adverse cardiovascular events and systemic hypertension, have reinforced this notion.¹

Despite this widespread belief, there has been little clinical trial evidence to support it. Measuring sodium intake is a difficult process and a significant obstacle to assessing the benefit of sodium restriction on reducing cardiovascular outcomes. Oftentimes, sodium intake is estimated based on recall questionnaires or formulas derived from urinary sodium excretion.¹

In addition, it is difficult for anyone in the general population—not just different patient groups—to adhere to a strict low sodium diet. This narrative review aims to analyze evidence garnered from the general population, as well as observational and randomized clinical trial evidence from the heart failure population, regarding reducing sodium intake to confirm or dispel the belief that it leads to better health outcomes.¹

The World Health Organization has published guidelines recommending less than 2 grams per day for the general population, while the American Heart Association calls for less than 1.5 grams per day. These conclusions were likely influenced by multiple observational and interventional studies showing a benefit in reducing sodium intake for controlling cardiovascular events.¹

“However, there is no agreement among scientists, nutritionists, and other specialists on the recommended daily sodium intake,” Paolo Raggi, the author of this review, wrote. Raggi described numerous trials that present contradicting claims regarding the benefits of sodium intake, with some authors taking aim at the limitations and potential biases of other trials, compounded by the overall difficulty of maintaining a low sodium diet.¹

Raggi writes that “in the absence of reliable methods to assess intake and the difficulty to maintain a low intake, it becomes impossible for the general public and patients to know exactly how much sodium they are ingesting and adhere to strict recommendations.”¹

Critically, Raggi notes that there has been no randomized evidence from large clinical trials that directly show a low sodium diet leading to a reduction in cardiovascular events in the general population.¹

Until recently, only very small randomized clinical trials addressed the morbidity and mortality effect of a low sodium diet in patients with HF. These trials ranged in size from 12 to 203 patients, had a mixture of patients with different types of HF, and varied in sodium interventions. None of the studies showed a reduction in hospitalization rate or mortality, according to Raggi.¹

Data from Ezekowtiz et al. brought substantial change to the landscape of this issue. Across 6 countries, 806 ambulatory HF patients were randomized to either a low sodium intake (less than 1.5 g per day) or a more liberal diet. The trial was open-label, controlled, and randomized.²

At a 12-month follow-up point, the primary outcome—a composite of cardiovascular-related admission to the hospital, a cardiovascular-related emergency department visit, or all-cause death—had occurred in 60 of 397 patients (15%) in the low sodium group and 70 of 409 patients (17%) in the standard care group (HR: 0.89; 95% CI, 0.63-1.26).²

Overall, Ezekowtiz et al. found that a dietary intervention to reduce sodium intake did not lead to a reduction in adverse clinical events.² Despite some potential limitations, including the short time period of the study and the effect of the COVID-19 pandemic, the results of the study “reflect what observational studies and metanalyses had suggested: no advantage is to be expected as far as morbidity and mortality,” according to Raggi.¹

Raggi suggests that a moderate sodium intake of 3 g to 4.5 g per day “seems prudent” to lead to better quality of life and functional status in patients with HF, while understanding that it will not improve hospitalization rate or life expectancy. For those with recurrent hospital admissions, 2 g to 3 g per day could be recommendable.¹

“Doctors often resist making changes to age-old tenets that have no true scientific basis; however, when new good evidence surfaces, we should make an effort to embrace it,” Raggi said in a news release.³

References
1. Raggi, P. Salt versus no salt restriction in heart failure: a review. Wiley. 2024. doi:10.1111/eci14265.

2. Ezekowtiz J, Colin-Ramirez E, Ross H, et al. Reduction of dietary sodium to less than 100 mmol in heart failure (SODIUM-HF): an international, open-label, randomized, controlled trial. Lancet. 2022;399(10333):1391-1400. doi:10.1016/S0140-6736(22)00369-5.

3. EurekAlert! Is it time to stop recommending strict salt restriction in people with heart failure? News release. Published June 26, 2024. Accessed July 2, 2024. https://www.eurekalert.org/news-releases/1049098