The science of salt: A regularly updated systematic review of salt and health outcomes (December 2015–March 2016)

Abstract

The purpose of this review was to identify, summarize, and critically appraise studies on dietary salt relating to health outcomes that were published from December 2015 to March 2016. The search strategy was adapted from a previous systematic review on dietary salt and health. Overall, 13 studies were included in the review: one study assessed cardiovascular events, nine studies assessed prevalence or incidence of blood pressure or hypertension, one study assessed kidney disease, and two studies assessed other health outcomes (obesity and nonalcoholic fatty liver disease). Four studies were selected for detailed appraisal and commentary. One study met the minimum methodologic criteria and found an increased risk associated with lower sodium intake in patients with heart failure. All other studies identified in this review demonstrated positive associations between dietary salt and adverse health outcomes. | INTRODUCTIONExcess salt (sodium) consumption is associated with many adverse health effects, including hypertension and cardiovascular mortality.1,2 Based on the evidence from systematic reviews assessing dietary sodium reduction, the World Health Organization (WHO) recommends a sodium intake of <2 g/d (equivalent to 5 g/d of salt) in adults, with lower amounts for children based on their energy requirements relative to those of adults. 3,4 All WHO Member States have agreed on a target of reducing dietary sodium intake by 30%by 2025. 5Regularly updated reviews and critical appraisals of identified studies relating to health outcomes are published in the Journal of Clinical Hypertension, alternating with reviews of studies relating to salt reduction implementation programs. The last review of salt and health outcomes covered studies published between August and November 2015. | METHODOLOGYA detailed description of the methodological approach used to identify and evaluate the literature in this review has been previously published. 7 In summary, articles were identified on a weekly basis through a MEDLINE search strategy. 7 Studies examining the effects of salt on health outcomes, including studies of participants with any comorbidity (with the exception of acute illness), that were published from December 1, 2015 to March 31, 2016, were included in this review.All included studies were assessed for risk of bias by two independent reviewers. Randomized controlled trials (RCTs) were assessed using the Cochrane risk of bias tool. 8 Observational, nonrandomized studies were assessed using a modified Cochrane risk of bias tool. 9 For systematic reviews and meta-analyses, the c tool was applied. 10We identified the subset of included studies that met previously established minimum methodologic criteria for clinical and population studies on dietary salt 11 (Box). Detailed appraisals and written commentary were performed for these studies. Other studies were then selected for detailed review based on two independent reviewers identifying them either as potentially high impact, controversial, or important in terms ...

The International Consortium for Quality Research on Dietary Sodium/Salt (TRUE) position statement on the use of 24‐hour, spot, and short duration (<24 hours) timed urine collections to assess dietary sodium intake

“…A priority is to develop minimum methodologic standards for the conduct of validation studies. A regularly updated systematic review of the literature assessing the association of sodium intake to clinical outcomes found the majority of studies could not meet even minimum methodologic criteria . The initial TRUE consortium position on blood pressure measurement in research studies was also developed because few research studies used the recommended methods to assess blood pressure .…”

“…A regularly updated systematic review of the literature assessing the association of sodium intake to clinical outcomes found the majority of studies could not meet even minimum methodologic criteria. [69][70][71][72][73][74] The initial TRUE consortium position on blood pressure measurement in research studies was also developed because few research studies used the recommended methods to assess blood pressure. 13 Institutions funding research, journals, and scientists need to carefully assess the validity of the methods used in research relating to dietary sodium to ensure reliable guidance to public health programs.…”

More evidence that salt increases blood pressure and risk of kidney disease from the Science of Salt: A regularly updated systematic review of salt and health outcomes (April–July 2016)

“…Up to May 2015, we annually published a summary of studies on salt and health outcomes . In June 2015, we replaced the annual reviews with regularly published summaries that include risk of bias assessments and critical appraisals . From June 2015 to July 2016, 64 studies were identified that met our inclusion criteria, ie, original human research on salt intake and health outcomes.…”

High salt‐induced excess reactive oxygen species production resulted in heart tube malformation during gastrulation

“…While our body requires a certain amount of salt to work properly, too much of it is bad for health. A report summarizing 13 studies from eight countries concluded that a high salt diet is closely related to cardiovascular events (Wong et al, ). According to the Centers for Disease Control and Prevention (CDC), most Americans consume too much sodium in their daily diet, with a current average of 3.4 g/d.…”