This protocol was withdrawn in February 2018 as the author team was unable to progress to the final review stage, however a review addressing this question was subsequently published by the author team as: Mahtani KR, Heneghan C, Onakpoya I, Tierney S, Aronson JK, Roberts N, et al. Reduced salt intake for heart failure: a systematic review. JAMA Internal Medicine 2018;178(12):1693–1700. https://doi.org/10.1001/jamainternmed.2018.4673