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December 2018

Reduced Salt Intake for Heart Failure: A Systematic Review

Author Affiliations
  • 1Centre for Evidence Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, United Kingdom
  • 2Knowledge Centre, Bodleian Libraries, Old Road Campus, University of Oxford, Oxford, United Kingdom
JAMA Intern Med. 2018;178(12):1693-1700. doi:10.1001/jamainternmed.2018.4673
Key Points

Question  What is the evidence that reduced dietary salt intake benefits adults with heart failure?

Findings  In this systematic review of 9 unique studies of 479 unique patients with heart failure, an overall paucity of robust high-quality evidence was available to support or refute the use of reduced dietary salt intake.

Meaning  Despite broad advocacy, uncertainty about the robustness of advice to reduce salt intake in patients with heart failure remains.


Importance  Recent estimates suggest that more than 26 million people worldwide have heart failure. The syndrome is associated with major symptoms, significantly increased mortality, and extensive use of health care. Evidence-based treatments influence all these outcomes in a proportion of patients with heart failure. Current management also often includes advice to reduce dietary salt intake, although the benefits are uncertain.

Objective  To systematically review randomized clinical trials of reduced dietary salt in adult inpatients or outpatients with heart failure.

Evidence Review  Several bibliographic databases were systematically searched, including the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, and CINAHL. The methodologic quality of the studies was evaluated, and data associated with primary outcomes of interest (cardiovascular-associated mortality, all-cause mortality, and adverse events, such as stroke and myocardial infarction) and secondary outcomes (hospitalization, length of inpatient stay, change in New York Heart Association [NYHA] functional class, adherence to dietary low-salt intake, and changes in blood pressure) were extracted.

Findings  Of 2655 retrieved references, 9 studies involving 479 unique participants were included in the analysis. None of the studies included more than 100 participants. The risks of bias in the 9 studies were variable. None of the included studies provided sufficient data on the primary outcomes of interest. For the secondary outcomes of interest, 2 outpatient-based studies reported that NYHA functional class was not improved by restriction of salt intake, whereas 2 studies reported significant improvements in NYHA functional class.

Conclusions and Relevance  Limited evidence of clinical improvement was available among outpatients who reduced dietary salt intake, and evidence was inconclusive for inpatients. Overall, a paucity of robust high-quality evidence to support or refute current guidance was available. This review suggests that well-designed, adequately powered studies are needed to reduce uncertainty about the use of this intervention.

Protocol Registration  PROSPERO Identifier: CRD42015019504

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1 Comment for this article
Delicate Balance of Salt
Sarosh Ahmed Khan, MBBS; MD; FACP | Naseem Medical Center, Baghe-Mehtab, Srinagar, Kashmir, India
Hyponatremia where the serum sodium is <135 mEq/L, is present in about 1/5th of acutely decompensated heart failure patients. This is often dilutional rather than depletional. The combination of very low dietary sodium intake in heart failure and exaggerated losses due to natriuretic diuretic therapy might lead to progressive depletion of whole-body sodium.

Loop diuretics interfere with the renal capacity to concentrate urine resulting in less reabsorption of free water and in the production of hypotonic urine—therefore relative protection against hyponatremia. However, in profound volume depletion loop diuretics will fail to elicit meaningful diuresis. This fall in glomerular
filtration rate in the presence of a strongly upregulated arginine vasopressin creates an environment for hyponatremia.

So even if the total body sodium may not be low, the delicate balance can tilt. Advising complete salt restriction will lead to tissue depletion of sodium as the patient is decongested. This can further lead to generalized weakness and drowsiness, both of which can be dangerous.

Thus individualization of treatment and frequent monitoring of electrolytes may the way out.