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Dietary Sodium Restriction: Still Searching for the Grains of Truth

      To the Editor:
      We read with great interest the review “Dietary Sodium Restriction: Take It With a Grain of Salt,” by DiNicolantonio et al.
      • DiNicolantonio J.J.
      • Niazi A.K.
      • Sadaf R.
      • O'Keefe J.H.
      • Lucan S.C.
      • Lavie C.J.
      Dietary sodium restriction: take it with a grain of salt.
      The authors point out the paucity of data linking dietary sodium restriction to reductions in cardiovascular events and provide an excellent and broad-based overview of many important studies. However, we want to raise several issues for comment.
      The authors conclude that “there is sound evidence that a low sodium diet leads to a worse cardiovascular prognosis in patients with systolic congestive heart failure….” This statement is based on several studies performed by a single Italian research group, in which large loop diuretic doses (100-500 mg/d furosemide equivalent) were continued for months in outpatient participants regardless of clinical status. For reference, the mean furosemide equivalent dose at hospital discharge in large North American and European studies is 50 to 80 mg/d,
      • Nunez J.
      • Nunez E.
      • Minana G.
      • et al.
      Differential mortality association of loop diuretic dosage according to blood urea nitrogen and carbohydrate antigen 125 following a hospitalization for acute heart failure.
      • Abdel-Qadir H.M.
      • Tu J.V.
      • Yun L.
      • Austin P.C.
      • Newton G.E.
      • Lee D.S.
      Diuretic dose and long-term outcomes in elderly patients with heart failure after hospitalization.
      and discharge furosemide doses of ≥240 mg/d predict higher mortality even in the very ill heart failure population in the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness study.
      • O'Connor C.M.
      • Hasselblad V.
      • Mehta R.H.
      • et al.
      Triage after hospitalization with advanced heart failure: the ESCAPE (Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness) risk model and discharge score.
      In this setting, it seems difficult to conclude that low-sodium diets “caused increased mortality and heart failure hospitalizations” rather than the known neurohormonal and renal effects of high-dose diuretics in the setting of volume depletion.
      Abundant data from animal models and humans suggest that at least some persons would benefit greatly from dietary sodium restriction. DiNicolantonio et al
      • DiNicolantonio J.J.
      • Niazi A.K.
      • Sadaf R.
      • O'Keefe J.H.
      • Lucan S.C.
      • Lavie C.J.
      Dietary sodium restriction: take it with a grain of salt.
      correctly characterize sodium consumption as physiologically regulated and challenging to modulate. However, it is not impossible to do so in populations, as evidenced by successful policy-driven sodium intake reductions in Finland and the United Kingdom.
      • Polonia J.
      • Martins L.
      A comprehensive review on salt and health and current experience of worldwide salt reduction programmes.
      We strongly believe that additional research, particularly in special populations such as those with heart failure, is needed before dismissing such efforts as potentially “counterproductive…and risky.”

      References

        • DiNicolantonio J.J.
        • Niazi A.K.
        • Sadaf R.
        • O'Keefe J.H.
        • Lucan S.C.
        • Lavie C.J.
        Dietary sodium restriction: take it with a grain of salt.
        Am J Med. 2013; 126: 951-955
        • Nunez J.
        • Nunez E.
        • Minana G.
        • et al.
        Differential mortality association of loop diuretic dosage according to blood urea nitrogen and carbohydrate antigen 125 following a hospitalization for acute heart failure.
        Eur J Heart Fail. 2012; 14: 974-984
        • Abdel-Qadir H.M.
        • Tu J.V.
        • Yun L.
        • Austin P.C.
        • Newton G.E.
        • Lee D.S.
        Diuretic dose and long-term outcomes in elderly patients with heart failure after hospitalization.
        Am Heart J. 2010; 160: 264-271
        • O'Connor C.M.
        • Hasselblad V.
        • Mehta R.H.
        • et al.
        Triage after hospitalization with advanced heart failure: the ESCAPE (Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness) risk model and discharge score.
        J Am Coll Cardiol. 2010; 55: 872-878
        • Polonia J.
        • Martins L.
        A comprehensive review on salt and health and current experience of worldwide salt reduction programmes.
        J Hum Hypertens. 2009; 23: 771-772

      Linked Article

      • Dietary Sodium Restriction: Take It with a Grain of Salt
        The American Journal of MedicineVol. 126Issue 11
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          The American Heart Association recently strongly recommended a dietary sodium intake of <1500 mg/d for all Americans to achieve “Ideal Cardiovascular Health” by 2020. However, low sodium diets have not been shown to reduce cardiovascular events in normotensive individuals or in individuals with pre-hypertension or hypertension. Moreover, there is evidence that a low sodium diet may lead to a worse cardiovascular prognosis in patients with cardiometabolic risk and established cardiovascular disease.
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      • The Reply
        The American Journal of MedicineVol. 127Issue 6
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          We thank Hummel and Weder for their response1 to our article2 pertaining to the potential harms of restricting dietary sodium. The 2 doctors suggest there is a lack of sound evidence that low-sodium diets increase hospitalizations and mortality versus normal-sodium diets because the trials cited in our review used unusual diuretic dosing. Specifically, Hummel and Weder are concerned about high doses of furosemide not commonly used in the United States or Europe. However, in the largest randomized trial we cite (n = 1771), investigators gave furosemide at a dose of 50 mg twice daily (ie, 100 mg/d) to approximately two thirds of all enrolled patients.
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