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Population-wide Sodium Reduction: Reasons to Resist

      To the Editor:
      In their review article in the September 2013 issue of Mayo Clinic Proceedings, Aaron and Sanders
      • Aaron K.J.
      • Sanders P.W.
      Role of dietary salt and potassium intake in cardiovascular health and disease: a review of the evidence.
      stated that “high salt intake not only increases blood pressure but also plays a role in endothelial dysfunction, cardiovascular structure and function, albuminuria and kidney disease progression, and cardiovascular morbidity and mortality in the general population” and that “the body of evidence supports population-wide sodium intake reduction.” What the authors neglect to mention is that reducing sodium intake has been associated with increases in renin, aldosterone, adrenaline, noradrenaline, cholesterol, and triglyceride levels.
      • Graudal N.A.
      • Hubeck-Graudal T.
      • Jurgens G.
      Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride.
      It is uncertain that the net result of sodium restriction would be positive for health given these potential adverse effects. Moreover, reducing sodium intake may worsen insulin resistance,
      • Garg R.
      • Williams G.H.
      • Hurwitz S.
      • Brown N.J.
      • Hopkins P.N.
      • Adler G.K.
      Low-salt diet increases insulin resistance in healthy subjects.
      increasing the prevalence of diabetes and prediabetes (already affecting approximately one-third of the entire US population

      Centers for Disease Control and Prevention. 2011 National Diabetes Fact Sheet. http://www.cdc.gov/diabetes/pubs/estimates11.htm#1). Updated October 25, 2013. Accessed October 17, 2013.

      ). Low-sodium diets could also exacerbate thyroid disease by reducing individuals' intake of iodine (obtained in most cases through ingestion of iodized salt).
      • Dasgupta P.K.
      • Liu Y.
      • Dyke J.V.
      Iodine nutrition: iodine content of iodized salt in the United States [published correction appears in Environ Sci Technol. 2008;42(18):7025].
      Additionally, sodium avoidance could lead to hyponatremia, for which much of the population may be at risk due to (1) life behaviors (eg, manual labor/strenuous exercise, when replacing sweat with free water), (2) commonly used medications (eg, selective serotonin reuptake inhibitors, tricyclic antidepressants, nonsteroidal anti-inflammatory agents, antipsychotics, and thiazide diuretics), or (3) prevalent disease states (eg, liver disease, cancer, and congestive heart failure).
      • Gupta N.
      • Jani K.K.
      • Gupta N.
      Hypertension: salt restriction, sodium homeostasis, and other ions.
      Regarding congestive heart failure in particular, what is even more worrisome is that randomized clinical trials have repeatedly suggested that restricting sodium intake to 1800 mg daily, compared with 2800 mg daily, is associated with increased rates of hospitalizations and mortality.
      • Licata G.
      • Di Pasquale P.
      • Parrinello G.
      • et al.
      Effects of high-dose furosemide and small-volume hypertonic saline solution infusion in comparison with a high dose of furosemide as bolus in refractory congestive heart failure: long-term effects.
      • Paterna S.
      • Di Pasquale P.
      • Parrinello G.
      • et al.
      Changes in brain natriuretic peptide levels and bioelectrical impedance measurements after treatment with high-dose furosemide and hypertonic saline solution versus high-dose furosemide alone in refractory congestive heart failure: a double-blind study.
      • Paterna S.
      • Fasullo S.
      • Parrinello G.
      • et al.
      Short-term effects of hypertonic saline solution in acute heart failure and long-term effects of a moderate sodium restriction in patients with compensated heart failure with New York Heart Association class III (Class C) (SMAC-HF study).
      • Paterna S.
      • Gaspare P.
      • Fasullo S.
      • Sarullo F.M.
      • Di Pasquale P.
      Normal-sodium diet compared with low-sodium diet in compensated congestive heart failure: is sodium an old enemy or a new friend?.
      Even if it were physiologically possible for individuals to sustainably reduce sodium intake—a proposition that science calls into question
      • McCarron D.A.
      • Drüeke T.B.
      • Stricker E.M.
      Science trumps politics: urinary sodium data challenge US dietary sodium guideline [editorial].
      —it is entirely possible that attempting to reduce population sodium consumption would do more harm than good. There are certainly many compelling reasons to resist the idea of population-wide sodium reduction. Moreover, recent literature suggests that markedly cutting back on sodium consumption may be much less important than increasing one's dietary potassium intake.
      • O'Donnell M.J.
      • Yusuf S.
      • Mente A.
      • et al.
      Urinary sodium and potassium excretion and risk of cardiovascular events.

      References

        • Aaron K.J.
        • Sanders P.W.
        Role of dietary salt and potassium intake in cardiovascular health and disease: a review of the evidence.
        Mayo Clin Proc. 2013; 88: 987-995
        • Graudal N.A.
        • Hubeck-Graudal T.
        • Jurgens G.
        Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride.
        Cochrane Database Syst Rev. 2011; : CD004022
        • Garg R.
        • Williams G.H.
        • Hurwitz S.
        • Brown N.J.
        • Hopkins P.N.
        • Adler G.K.
        Low-salt diet increases insulin resistance in healthy subjects.
        Metabolism. 2011; 60: 965-968
      1. Centers for Disease Control and Prevention. 2011 National Diabetes Fact Sheet. http://www.cdc.gov/diabetes/pubs/estimates11.htm#1). Updated October 25, 2013. Accessed October 17, 2013.

        • Dasgupta P.K.
        • Liu Y.
        • Dyke J.V.
        Iodine nutrition: iodine content of iodized salt in the United States [published correction appears in Environ Sci Technol. 2008;42(18):7025].
        Environ Sci Technol. 2008; 42: 1315-1323
        • Gupta N.
        • Jani K.K.
        • Gupta N.
        Hypertension: salt restriction, sodium homeostasis, and other ions.
        Indian J Med Sci. 2011; 65: 121-132
        • Licata G.
        • Di Pasquale P.
        • Parrinello G.
        • et al.
        Effects of high-dose furosemide and small-volume hypertonic saline solution infusion in comparison with a high dose of furosemide as bolus in refractory congestive heart failure: long-term effects.
        Am Heart J. 2003; 145: 459-466
        • Paterna S.
        • Di Pasquale P.
        • Parrinello G.
        • et al.
        Changes in brain natriuretic peptide levels and bioelectrical impedance measurements after treatment with high-dose furosemide and hypertonic saline solution versus high-dose furosemide alone in refractory congestive heart failure: a double-blind study.
        J Am Coll Cardiol. 2005; 45: 1997-2003
        • Paterna S.
        • Fasullo S.
        • Parrinello G.
        • et al.
        Short-term effects of hypertonic saline solution in acute heart failure and long-term effects of a moderate sodium restriction in patients with compensated heart failure with New York Heart Association class III (Class C) (SMAC-HF study).
        Am J Med Sci. 2011; 342: 27-37
        • Paterna S.
        • Gaspare P.
        • Fasullo S.
        • Sarullo F.M.
        • Di Pasquale P.
        Normal-sodium diet compared with low-sodium diet in compensated congestive heart failure: is sodium an old enemy or a new friend?.
        Clin Sci (Lond). 2008; 114: 221-230
        • McCarron D.A.
        • Drüeke T.B.
        • Stricker E.M.
        Science trumps politics: urinary sodium data challenge US dietary sodium guideline [editorial].
        Am J Clin Nutr. 2010; 92: 1005-1006
        • O'Donnell M.J.
        • Yusuf S.
        • Mente A.
        • et al.
        Urinary sodium and potassium excretion and risk of cardiovascular events.
        JAMA. 2011; 306: 2229-2238

      Linked Article

      • Role of Dietary Salt and Potassium Intake in Cardiovascular Health and Disease: A Review of the Evidence
        Mayo Clinic ProceedingsVol. 88Issue 9
        • Preview
          The objective of this review was to provide a synthesis of the evidence on the effect of dietary salt and potassium intake on population blood pressure, cardiovascular disease, and mortality. Dietary guidelines and recommendations are outlined, current controversies regarding the evidence are discussed, and recommendations are made on the basis of the evidence. Designed search strategies were used to search various databases for available studies. Randomized trials of the effect of dietary salt intake reduction or increased potassium intake on blood pressure, target organ damage, cardiovascular disease, and mortality were included.
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      • In Reply—Population-wide Sodium Reduction: Reasons to Resist
        Mayo Clinic ProceedingsVol. 89Issue 3
        • Preview
          A discussion of salt intake always generates a vigorous debate. In some part, controversy occurs because of the years of study generally required to determine the effect of dietary modifications on morbidity and mortality. Perhaps as a result, association studies have proliferated in this area to replace randomized controlled trials. However, the field of nephrology in particular has learned a series of “tough lessons” as a result of relying on observational data and is now emphasizing the need for randomized controlled studies to dictate clinical practice.
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