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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    • "Na is an important element in the regulation of blood pressure, blood volume, acid–base balance, nerve impulse transmission, muscle function and normal cell function. However, accumulating evidence suggests that the average consumption of Na in the world is well above the necessary intake for the correct functioning of the body (Elinge et al., 2012; Aburto et al., 2013). Most of the analyzed samples showed low levels of Na; thus, these fruits can be included in the diet to improve the nutritional quality of people who need dietary restriction of Na. "

    • "Our results were consistent with two recent systematic reviews which reported a significant reduction in BP by low sodium and high potassium intake. It has been estimated that low sodium intake may reduce SBP by 3.39 mmHg and DBP by 1.54 mmHg in adults [55]. Figure 2 Effect of the DASH diet on systolic blood pressure in randomized controlled trials among adults: by hypertension status. "
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    ABSTRACT: Background and Aims Findings were not consistent on the therapeutic effect of Dietary Approaches to Stop Hypertension (DASH) diet on blood pressure. We aimed to review systematically and perform a meta-analysis to assess the magnitude of the effect of the DASH diet on blood pressure in randomized controlled trials (RCTs) among adults. Methods and Results We conducted a systematic review and random effects meta-analysis of all RCTs which evaluated the effect of the DASH diet on blood pressure including published papers until June 2013, using PubMed, ISI Web of Science, Scopus and Google scholar database. Subgroup analysis and meta-regression were used to find out possible sources of between-study heterogeneity. Seventeen RCTs contributing 20 comparisons with 2561 participants were included. Meta-analysis showed that the DASH diet significantly reduced systolic blood pressure by 6.74 mmHg (95%CI: -8.25,-5.23, I2=78.1%) and diastolic blood pressure by 3.54 mmHg (95%CI: -4.29,-2.79, I2=56.7%). RCTs with the energy restriction and those with hypertensive subjects showed a significantly greater decrease in blood pressure. Meta-regression showed that mean baseline of SBP and DBP was explained 24% and 49% of the variance between studies for SBP and DBP, respectively. Conclusion The results revealed the profitable reducing effect of the DASH-like diet on both systolic and diastolic blood pressure in adults; although there was a variation in the extent of the fall in blood pressure in different subgroups.
    Nutrition Metabolism and Cardiovascular Diseases 12/2014; 24(12). DOI:10.1016/j.numecd.2014.06.008 · 3.32 Impact Factor
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    • "Cerebral circulation is vulnerable to excess salt as shown in clinical studies [1], [2]. Experimental studies have also reported detrimental effects of excess salt on cerebral arteries. "
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    ABSTRACT: Cerebral circulation is known to be vulnerable to high salt loading. However, no study has investigated the effects of excess salt on focal ischemic brain injury. After 14 days of salt loading (0.9% saline) or water, spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) were subjected to photothrombotic middle cerebral artery occlusion (MCAO), and infarct volume was determined at 48 h after MCAO: albumin and hemoglobin contents in discrete brain regions were also determined in SHR. Salt loading did not affect blood pressure levels in SHR and WKY. After MCAO, regional cerebral blood flow (CBF), determined with two ways of laser-Doppler flowmetry (one-point measurement or manual scanning), was more steeply decreased in the salt-loaded group than in the control group. In SHR/Izm, infarct volume in the salt-loaded group was 112±27 mm3, which was significantly larger than 77±12 mm3 in the control group (p = 0.002), while the extents of blood-brain barrier disruption (brain albumin and hemoglobin levels) were not affected by excess salt. In WKY, salt loading did not significantly increase infarct size. These results show the detrimental effects of salt loading on intra-ischemic CBF and subsequent brain infarction produced by phototrhombotic MCAO in hypertensive rats.
    PLoS ONE 05/2014; 9(5):e97109. DOI:10.1371/journal.pone.0097109 · 3.23 Impact Factor
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