Effect of lower sodium intake on health: Systematic review and meta-analyses

Nutrition Policy and Scientific Advice Unit, Department of Nutrition for Health and Development, World Health Organization, 1211 Geneva 27, Switzerland.
BMJ (online) (Impact Factor: 17.45). 04/2013; 346(apr03 3):f1326. DOI: 10.1136/bmj.f1326
Source: PubMed


To assess the effect of decreased sodium intake on blood pressure, related cardiovascular diseases, and potential adverse effects such as changes in blood lipids, catecholamine levels, and renal function.
Systematic review and meta-analysis.
Cochrane Central Register of Controlled Trials, Medline, Embase, WHO International Clinical Trials Registry Platform, the Latin American and Caribbean health science literature database, and the reference lists of previous reviews.
Randomised controlled trials and prospective cohort studies in non-acutely ill adults and children assessing the relations between sodium intake and blood pressure, renal function, blood lipids, and catecholamine levels, and in non-acutely ill adults all cause mortality, cardiovascular disease, stroke, and coronary heart disease. STUDY APPRAISAL AND SYNTHESIS: Potential studies were screened independently and in duplicate and study characteristics and outcomes extracted. When possible we conducted a meta-analysis to estimate the effect of lower sodium intake using the inverse variance method and a random effects model. We present results as mean differences or risk ratios, with 95% confidence intervals.
We included 14 cohort studies and five randomised controlled trials reporting all cause mortality, cardiovascular disease, stroke, or coronary heart disease; and 37 randomised controlled trials measuring blood pressure, renal function, blood lipids, and catecholamine levels in adults. Nine controlled trials and one cohort study in children reporting on blood pressure were also included. In adults a reduction in sodium intake significantly reduced resting systolic blood pressure by 3.39 mm Hg (95% confidence interval 2.46 to 4.31) and resting diastolic blood pressure by 1.54 mm Hg (0.98 to 2.11). When sodium intake was <2 g/day versus ≥2 g/day, systolic blood pressure was reduced by 3.47 mm Hg (0.76 to 6.18) and diastolic blood pressure by 1.81 mm Hg (0.54 to 3.08). Decreased sodium intake had no significant adverse effect on blood lipids, catecholamine levels, or renal function in adults (P>0.05). There were insufficient randomised controlled trials to assess the effects of reduced sodium intake on mortality and morbidity. The associations in cohort studies between sodium intake and all cause mortality, incident fatal and non-fatal cardiovascular disease, and coronary heart disease were non-significant (P>0.05). Increased sodium intake was associated with an increased risk of stroke (risk ratio 1.24, 95% confidence interval 1.08 to 1.43), stroke mortality (1.63, 1.27 to 2.10), and coronary heart disease mortality (1.32, 1.13 to 1.53). In children, a reduction in sodium intake significantly reduced systolic blood pressure by 0.84 mm Hg (0.25 to 1.43) and diastolic blood pressure by 0.87 mm Hg (0.14 to 1.60).
High quality evidence in non-acutely ill adults shows that reduced sodium intake reduces blood pressure and has no adverse effect on blood lipids, catecholamine levels, or renal function, and moderate quality evidence in children shows that a reduction in sodium intake reduces blood pressure. Lower sodium intake is also associated with a reduced risk of stroke and fatal coronary heart disease in adults. The totality of evidence suggests that most people will likely benefit from reducing sodium intake.

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Available from: Francesco Cappuccio, May 23, 2015
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    • "Excess sodium intake raises blood pressure, leading to hypertension, the principal preventable risk factor for stroke[6,7]. Excess sodium is also a major risk factor for other CVDs and for stomach cancer678. It is possible that populations in sub-Saharan Africa are more vulnerable to the effects of a high sodium diet than other populations due to the greater prevalence of inter-uterine growth restriction, as well as genetic factors[9,10]. "
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    ABSTRACT: High sodium intake increases the risk of hypertension and cardiovascular diseases. For this reason the World Health Organization recommends a maximum intake of 2 g per day and a 30 % reduction in population sodium intake by 2025. However, in global reviews, data on sodium intake in sub-Saharan Africa have been limited. A systematic review was conducted to identify studies reporting sodium intake in sub-Saharan African populations. Meta-regression analyses were used to test the effect of year of data collection and method of data collection (urinary/dietary), as well as any association between sex, urban/rural status or a country’s economic development, and population sodium intake. We identified 42 papers reporting 67 estimates of adult population sodium intakes and 12 estimates of child population sodium intakes since 1967. Of the 67 adult populations, 54 (81 %) consumed more than 2 g sodium/day, as did four of the 12 (33 %) child populations. Sixty-five adult estimates were included in the meta-regression, which found that urban populations consumed higher amounts of salt than rural populations and that urine collection gave lower estimates of sodium intake than dietary data. Sodium intake in much of sub-Saharan Africa is above the World Health Organization’s recommended maximum intake and may be set to increase as the continent undergoes considerable urbanization. Few identified studies used stringent measurement criteria or representative population samples. High quality studies will be required to identify where and with whom to intervene, in order to meet the World Health Organization’s target of a 30 % reduction in population sodium intake and to demonstrate progress towards this target.
    Full-text · Article · Dec 2016 · Population Health Metrics
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    • "A currently available salt substitute in China is composed of 65% NaCl, 25% potassium chloride, and 10% magnesium sulfate [12, 13]. Both increased potassium and magnesium intake and reduce dietary salt lower mean BP [3,27282930. Because the sodium, potassium, and magnesium components of the salt substitute influence BP change, we input the direct BP effects observed in trials when simulating salt substitute interventions. "
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    ABSTRACT: Objectives: To estimate the effects of achieving China's national goals for dietary salt (NaCl) reduction or implementing culturally-tailored dietary salt restriction strategies on cardiovascular disease (CVD) prevention. Methods: The CVD Policy Model was used to project blood pressure lowering and subsequent downstream prevented CVD that could be achieved by population-wide salt restriction in China. Outcomes were annual CVD events prevented, relative reductions in rates of CVD incidence and mortality, quality-adjusted life-years (QALYs) gained, and CVD treatment costs saved. Results: Reducing mean dietary salt intake to 9.0 g/day gradually over 10 years could prevent approximately 197 000 incident annual CVD events [95% uncertainty interval (UI): 173 000-219 000], reduce annual CVD mortality by approximately 2.5% (2.2-2.8%), gain 303 000 annual QALYs (278 000-329 000), and save approximately 1.4 billion international dollars (Int$) in annual CVD costs (Int$; 1.2-1.6 billion). Reducing mean salt intake to 6.0 g/day could approximately double these benefits. Implementing cooking salt-restriction spoons could prevent 183 000 fewer incident CVD cases (153 000-215 000) and avoid Int$1.4 billion in CVD treatment costs annually (1.2-1.7 billion). Implementing a cooking salt substitute strategy could lead to approximately three times the health benefits of the salt-restriction spoon program. More than three-quarters of benefits from any dietary salt reduction strategy would be realized in hypertensive adults. Conclusion: China could derive substantial health gains from implementation of population-wide dietary salt reduction policies. Most health benefits from any dietary salt reduction program would be realized in adults with hypertension.
    Full-text · Article · Feb 2016 · PLoS ONE
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    • "Hypertension is associated with high intakes of sodium (Aburto et al., 2013; "
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    ABSTRACT: Purpose: The purpose of this study was to provide baseline estimates of sodium levels in 125 popular, sodium-contributing, commercially processed and restaurant foods in the U.S., to assess future changes as manufacturers reformulate foods. Methods: In 2010-2013, we obtained ~ 5200 sample units from up to 12 locations and analyzed 1654 composites for sodium and related nutrients (potassium, total dietary fiber, total and saturated fat, and total sugar), as part of the U.S. Department of Agriculture-led sodium-monitoring program. We determined sodium content as mg/100 g, mg/serving, and mg/kcal and compared them against U.S. Food and Drug Administration's (FDA) sodium limits for "low" and "healthy" claims and to the optimal sodium level of < 1.1 mg/kcal, extrapolating from the Healthy Eating Index-2010. Results: Results from this study represent the baseline nutrient values to use in assessing future changes as foods are reformulated for sodium reduction. Sodium levels in over half (69 of 125) of the foods, including all main dishes and most Sentinel Foods from fast-food outlets or restaurants (29 of 33 foods), exceeded the FDA sodium limit for using the claim "healthy". Only 13 of 125 foods had sodium values below 1.1 mg/kcal. We observed a wide range of sodium content among similar food types and brands. Conclusions: Current sodium levels in commercially processed and restaurant foods in the U.S. are high and variable. Targeted benchmarks and increased awareness of high sodium content and variability in foods would support reduction of sodium intakes in the U.S.
    Full-text · Article · Nov 2015
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