The Effects of a Community-Based Sodium Reduction Program in Rural China – A Cluster-Randomized Trial

Abstract

BackgroundAverage sodium intake and stroke mortality in northern China are both among the highest in the world. An effective, low-cost strategy to reduce sodium intake in this population is urgently needed.ObjectiveWe sought to determine the effects of a community-based sodium reduction program on salt consumption in rural northern China.DesignThis study was a cluster-randomized trial done over 18 months in 120 townships (one village from each township) from five provinces. Sixty control villages were compared to 60 intervention villages that were given access to a reduced-sodium, added-potassium salt substitute in conjunction with a community-based health education program focusing on sodium reduction. The primary outcome was the difference in 24-hour urinary sodium excretion between randomized groups.ResultsAmong 1,903 people with valid 24-hour urine collections, mean urinary sodium excretion in intervention compared with control villages was reduced by 5.5% (-14mmol/day, 95% confidence interval -26 to -1; p = 0.03), potassium excretion was increased by 16% (+7mmol/day, +4 to +10; p<0.001), and sodium to potassium ratio declined by 15% (-0.9, -1.2 to -0.5; p<0.001). Mean blood pressure differences were -1.1 mm Hg systolic (-3.3 to +1.1; p = 0.33) and -0.7 mm Hg diastolic (-2.2 to +0.8, p = 0.35) and the difference in the proportion with hypertension was -1.3% (-5.1 to 2.5, p = 0.56).ConclusionThere were clear differences in population sodium and potassium intake between villages that were most likely a consequence of increased use of salt substitute. The absence of effects on blood pressure reflects the moderate changes in sodium and potassium intake achieved.Trial RegistrationClinicaltrials.gov identifier: NCT01259700.

The Science of Salt: A regularly updated systematic review of the implementation of salt reduction interventions (September 2016–February 2017)

“…Of the two studies using 24-hour urinary sodium as an outcome measurement method, one had a more scientifically robust design: a cluster RCT by Li and colleagues. 17 This study reliably reports a statistically significant decrease in salt intake among the study population and provides encouraging evidence that community-based health education in addition to a low-sodium salt substitute are effective in reducing dietary salt consumption.…”

“…Four of seven studies showed statistically significant decreases in the dietary salt intakes of study populations as a result of behavior interventions: one large repeated cross-sectional population study, 15 two small community-based studies (one that provided nutritional counseling in a University setting 16 and another that provided cooking classes in a rural setting), and one large cluster randomized trial including a salt substitute combined with consumer education intervention. 17 Of the remaining three studies, one found statistically significant decreases in mean sodium density of packaged food products following a national salt reduction initiative for voluntary, category-specific sodium targets for packaged food. The other two studies found significant improvements in nutrition behaviors relating to salt intake after consumer education in a pilot study 18 and a community-based RCT.…”

“…20 The Science of reduce the risk of selection bias in their small sample; however, because participants were not blinded to the intervention, the risk of performance bias was increased because of participant knowledge of which intervention was received, rather than the intervention itself affecting the outcome of the study. While two 16,17 of the six studies evaluating salt intake measured sodium excretion by 24-hour urine samples, Irwan and colleagues 19 estimated salt intake using a salinity checker that was not validated in the population studied nor against a gold standard 24-hour urine sample, limiting the validity and reliability of the outcome measurement. Of the two studies using 24-hour urinary sodium as an outcome measurement method, one had a more scientifically robust design: a cluster RCT by Li and colleagues.…”

Letter to the editor on “Potential use of salt substitutes to reduce blood pressure”

“…Furthermore, evidence from the cluster RCT in rural China where potassium salts were provided to 60 villages produced statistically but not clinically significant reductions in sodium intake (mean reduction of sodium intake was 14 mmol per day). 5 There is also emerging evidence that salt reduction strategies are most effective when targeted to those in the highest quartile of intake and not the general population. 6 Second, the statement by the authors that "use of salt substitutes as a public health intervention warrants consideration as part of policy recommendations" is of great concern to us.…”

Rationale, design, and baseline characteristics of the Salt Substitute in India Study (SSiIS): The protocol for a double‐blinded, randomized‐controlled trial

“…Although a systematic review and meta‐analysis of clinical studies have demonstrated blood pressure lowering effects of reduced‐sodium, added‐potassium salt substitutes, 16 such studies have to date mostly been conducted in China 17‐20 . Given the high prevalence of excess sodium intake in India, the current study set out to test the effect of salt substitute on BP among hypertensive patients in India.…”