Systematic review of dietary salt reduction policies: Evidence for an effectiveness hierarchy?

Abstract

BackgroundNon-communicable disease (NCD) prevention strategies now prioritise four major risk factors: food, tobacco, alcohol and physical activity. Dietary salt intake remains much higher than recommended, increasing blood pressure, cardiovascular disease and stomach cancer. Substantial reductions in salt intake are therefore urgently needed. However, the debate continues about the most effective approaches. To inform future prevention programmes, we systematically reviewed the evidence on the effectiveness of possible salt reduction interventions. We further compared “downstream, agentic” approaches targeting individuals with “upstream, structural” policy-based population strategies.MethodsWe searched six electronic databases (CDSR, CRD, MEDLINE, SCI, SCOPUS and the Campbell Library) using a pre-piloted search strategy focussing on the effectiveness of population interventions to reduce salt intake. Retrieved papers were independently screened, appraised and graded for quality by two researchers. To facilitate comparisons between the interventions, the extracted data were categorised using nine stages along the agentic/structural continuum, from “downstream”: dietary counselling (for individuals, worksites or communities), through media campaigns, nutrition labelling, voluntary and mandatory reformulation, to the most “upstream” regulatory and fiscal interventions, and comprehensive strategies involving multiple components.ResultsAfter screening 2,526 candidate papers, 70 were included in this systematic review (49 empirical studies and 21 modelling studies). Some papers described several interventions. Quality was variable. Multi-component strategies involving both upstream and downstream interventions, generally achieved the biggest reductions in salt consumption across an entire population, most notably 4g/day in Finland and Japan, 3g/day in Turkey and 1.3g/day recently in the UK. Mandatory reformulation alone could achieve a reduction of approximately 1.45g/day (three separate studies), followed by voluntary reformulation (-0.8g/day), school interventions (-0.7g/day), short term dietary advice (-0.6g/day) and nutrition labelling (-0.4g/day), but each with a wide range. Tax and community based counselling could, each typically reduce salt intake by 0.3g/day, whilst even smaller population benefits were derived from health education media campaigns (-0.1g/day). Worksite interventions achieved an increase in intake (+0.5g/day), however, with a very wide range. Long term dietary advice could achieve a -2g/day reduction under optimal research trial conditions; however, smaller reductions might be anticipated in unselected individuals.ConclusionsComprehensive strategies involving multiple components (reformulation, food labelling and media campaigns) and “upstream” population-wide policies such as mandatory reformulation generally appear to achieve larger reductions in population-wide salt consumption than “downstream”, individually focussed interventions. This ‘effectiveness hierarchy’ might deserve greater emph...

The Economic Impact of Dietary Sodium Reduction In Canada

“…Experience from countries like Japan, Finland, and the United Kingdom suggest that sustained reductions in population dietary sodium intake of 1700-1800mg/day are possible (65), and lead to large health gains for resource investments that are a fraction of the cost required for clinical hypertension control strategies (58,(61)(62)(63). Our findings support a call to action for a national regulatory program to reduce dietary sodium consumption.…”

“…Evidence from public health programs for tobacco control and alcohol policies support structural interventions achieving consistently larger improvements in population health, compared to individual and intermediate level interventions (61)(62)(63). This indicated the existence of a public health 'effectiveness hierarchy', and structural interventions were the best approach to consider in the implementation of a public health program (58,(61)(62)(63). A recent systematic review assessed the effectiveness of different intervention programs to reduce sodium intake.…”

“…A recent systematic review assessed the effectiveness of different intervention programs to reduce sodium intake. It found that a public health 'effectiveness hierarchy' did exist with structural interventions consistently achieving better health outcomes than individual level interventions (58,(61)(62)(63)(64).…”

“…Currently, there is considerable variation in strategies, and policy options to reduce dietary sodium consumption; however, evidence from a recent systematic review supports comprehensive strategies involving multiple components (product reformulation, food labeling and media campaigns/consumer awareness) to achieve larger reductions in population-wide sodium consumption (58,120). The review concludes that a combination of the three components is needed.…”

“…Evidence from Finland, Japan and the UK support a combination program encompassing product reformulation, food labeling and media campaigns/consumer awareness as well (58,120). The Finnish population implemented a multi-prong approach in the 1970s, and achieved an average reduction in dietary sodium of 1573 mg/day (58,(61)(62)(63). Stroke and CHD mortality fell by 52% and 15%, respectively over 30 years (68,69).…”