Review
Dietary Sodium Restriction: Take It with a Grain of Salt

https://doi.org/10.1016/j.amjmed.2013.05.020Get rights and content

Abstract

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. Low sodium diets may adversely affect insulin resistance, serum lipids, and neurohormonal pathways, leading to increases in the incidence of new cardiometabolic disease, the severity of existing cardiometabolic disease, and greater cardiovascular and all-cause mortality. Although a high sodium intake also may be deleterious, there is good reason to believe that sodium intake is regulated within such a tight physiologic range that there is little risk to leaving sodium intake to inherent biology as opposed to likely futile attempts at conscious control.

Section snippets

Salt and Blood Pressure

Much of the support for the idea that a low sodium diet leads to a lower blood pressure comes from the Dietary Approaches to Stop Hypertension (DASH) study.6 This study enrolled 412 participants and randomly assigned them to receive the control diet or the DASH diet. In both groups, the participants were assigned randomly to a high sodium diet (150 mmol/d), normal sodium diet (100 mmol/d), or low sodium diet (50 mmol/d) for 30 consecutive days and were then crossed over within their assigned

Patient-oriented Outcomes: Morbidity and Mortality

Congestive heart failure is characterized by various processes that lead to reduced renal perfusion and activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system.8 This leads to preferential retention of water compared with sodium and can cause hyponatremia. Restricted dietary sodium intake may further exacerbate these processes, therefore precipitating hyponatremia.

A study9 enrolled 410 patients with congestive heart failure and followed them for 6 months to

Other Unintended Consequences Relevant to Cardiovascular Health

A Cochrane review based on 167 studies showed that a low sodium diet in normotensive whites leads to a small reduction in systolic blood pressure (−1.27 mm Hg; CI, −1.88 to −0.66; P = .0001), without significantly reducing diastolic blood pressure (−0.05 mm Hg; CI, −0.51 to 0.42; P = .85).22 However, a low sodium diet caused an increase in renin (P < .00001), aldosterone (P < .00001), noradrenaline (P < .00001), adrenaline (P < .0002), cholesterol (P < .001), and triglycerides (P < .0008). This

Conclusions

There is no conclusive evidence that a low sodium diet reduces cardiovascular events in normotensive and pre-hypertensive or hypertensive individuals. On the contrary, there is sound evidence that a low sodium diet leads to a worse cardiovascular prognosis in patients with systolic congestive heart failure or type 2 diabetes mellitus. Worldwide sodium restriction, through its adverse effects on insulin resistance, may lead to an increase in the rates of type 2 diabetes mellitus. By potentially

References (25)

  • O. Ciani et al.

    Comparison of treatment effect sizes associated with surrogate and final patient relevant outcomes in randomised controlled trials: meta-epidemiological study

    BMJ

    (2013)
  • N.A. Graudal et al.

    Effects of sodium restriction on blood pressure, renin, aldosterone, catecholamines, cholesterols and triglyceride

    JAMA

    (1998)
  • Cited by (0)

    Funding: None.

    Conflict of Interest: None.

    Authorship: All authors had access to the data and played a role in writing this manuscript.

    View full text