The Science of Salt: A Regularly Updated Systematic Review of the Implementation of Salt Reduction Interventions (June–October 2015)

Evidence from comprehensive systematic reviews and high-quality studies demonstrates that excess salt intake causes raised blood pressure, a major risk factor for cardiovascular diseases.1, 2 Worldwide, nearly every country (181 of 187) consumes in excess of the World Health Organization (WHO)–recommended maximum intake of 5 g of salt per day.3 The United Nations and WHO have therefore called on Member States to reduce mean population salt intake by 30% by 2025.4 Between 2010 and 2014, the number of countries reporting some form of national salt reduction initiative more than doubled from 32 to 75.5 There are also other efforts to reduce population salt intake at subnational organizational, community, state, and provincial levels. An increasing number of programs are now being documented in order to share experiences and outcomes. It is within this context that this review aims to appraise studies reporting on the implementation of salt reduction initiatives that were identified as part of the Science of Salt Weekly systematic review series, with a view to informing future implementation of interventions to lower population salt consumption.6 A companion review aims to regularly summarize the growing volume of studies reporting the effects of salt intake on health outcomes.7 Articles are identified on a weekly basis through a MEDLINE search strategy that was formulated using a Cochrane Collaboration systematic review on dietary salt and health.2, 8 The search retrieved studies on the implementation of salt reduction strategies from June 2, 2015 to October 31, 2015. The methodological approach used to identify and evaluate the literature in this review has been described in a previously published protocol.6 The review includes studies reporting or evaluating salt reduction interventions and studies that provide information pertinent to the design of salt reduction interventions. The studies are considered in four broad categories: (1) studies evaluating the impact of salt reduction interventions; (2) descriptive studies describing salt reduction initiatives being implemented; (3) studies measuring population salt intake, salt content in foods, sources of dietary salt, or consumers' knowledge, attitudes, and behaviors (KAB) related to salt; and (4) economic evaluations or modeling studies of salt reduction strategies. Overviews of regional support activities without details of specific intervention programs were excluded. Each study was appraised for risk of bias (ROB) and quality. To assess the ROB for studies evaluating the impact of population-wide interventions, an adapted version of the Cochrane ROB tool developed for the review of population-level interventions in government jurisdictions was used.9, 10 The same tool was used for studies measuring salt content in foods and studies examining the association between salt knowledge and intake. In order to determine how accurately population salt intake was measured, an ROB assessment was made based on WHO recommendations for measurement of population sodium intake,11, 12 National Heart, Lung, and Blood Institute of the US Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies,13 and the ROB assessment tool developed previously for intervention studies.10 A modified version of standard quality-assessment guidelines for decision analytic modeling studies was used to assess the quality of modeling studies.14 It was not possible to assess the ROB for reviews of salt reduction initiatives being implemented nationally or regionally, thus the quality of these reviews was assessed against the draft framework defined by the WHO SALT toolkit for salt reduction. The MEDLINE search identified 2583 possibly relevant studies, of which 265 full-text articles were assessed against the eligibility criteria after elimination of irrelevant studies based on screening of the titles and abstracts (Figure). Ultimately, there were 11 studies included in this review: four reported interventions being implemented (one of which also evaluated a pilot salt reduction intervention)15-18 two cross-sectional studies, which measured population salt intake19, 20 two repeated cross-sectional studies on salt content of foods21, 22 one single cross-sectional study on salt content in foods23 one cross-sectional study on the association of salt knowledge and daily salt intake24 and one scenario modeling study.25 The appraisals of each study can be found as part of the online supplementary information (Appendix S1). Enkhtungalag B, Batjargal J, Chimedsuren O, et al. Cardiovasc Diagn Ther. 2015;5:229–237. Summary. Enkhtungalag and colleagues outline the development of a proposed national salt reduction strategy in Mongolia, including baseline population assessment of adult salt intake and pilot intervention strategies. The review includes a description of a pilot initiative (Pinch Salt Mongolia), which aimed to reduce salt intake among employees of three food-producing factories during a period of 2 years. The intervention included health and nutrition education for staff as well as reformulation of foods at company canteens and workers' kitchens. Pre-intervention and post-intervention 24-hour urine samples were collected for 240 employees who also completed a questionnaire about their KAB regarding salt. Results demonstrated a significant reduction in mean salt intake for employees from 11.48 g (standard deviation, 7.32 g) (sodium 4592 mg) per day in 2011 to 8.65 g (standard deviation, 4.26 g) (sodium 1704 mg) per day in 2013 and improved consumer knowledge about which foods were high in salt. The salt content of meals served in company kitchens also reduced over the period. Comment. Pinch Salt Mongolia is a pilot study that tests the feasibility of a workplace salt reduction initiative in Mongolia. There is limited detail about the pilot study as it is reported as part of a broader review of Mongolia's strategy. It is unclear from the paper how they were sampled and recruited and whether the sample was representative of the entire staff. Because of its uncontrolled study design, it is also likely to have a high risk of bias. Although the study showed a large reduction in salt intake based on 24-hour urine samples, which is usually a reliable method for assessment, it was unclear whether all the urine collections were complete. However, the results align with improvements in knowledge and the salt content of meals served. This pilot study usefully informs the development of a national salt reduction strategy. Webster J, Trieu K. Dunford E, et al. Cardiovasc Diagn Ther. 2015;5:207–218. Summary. This paper provides an overview of salt reduction activities in Australia against an existing framework for salt reduction strategies and identifies gaps where further action is required. It describes both nongovernmental organizations (NGOs) and government action over the past decade and states that Australia lacks a government-coordinated national implementation program, which is required to meet global salt reduction targets. Existing estimates of salt intake are between 8 g/d and 9 g/d (sodium 3200–3600 mg). However, there is no nationally representative baseline survey and no agreed upon mechanisms for ongoing monitoring. While food industry reformulation has been promoted over several decades by government and NGOs and reductions in salt content in some food categories have been measured, the government's Food and Health Dialogue did not set salt level targets in all key product categories. The more recent Health Star Rating system (a front-of-pack labeling scheme) has the potential to support improved consumer choices relating to salt as well as to drive food industry reformulation. There are plans for a consumer education campaign to support the rollout of the scheme. In Victoria, the Victorian Health Promotion Foundation has launched a state-wide salt reduction strategy with a view to supporting existing federal government programs, but action in other states is currently limited to policies or guidelines in schools or hospitals. It is not clear what the impact of these is likely to be. Comment. The authors conclude that additional efforts and more robust national monitoring mechanisms will be required for Australia to achieve a 30% reduction in salt by 2025. The overview of salt reduction initiatives in Australia over the past decade is comprehensive. It is based on a review of the literature and documentation of stakeholder activities and assesses these activities against an existing framework for salt reduction. It also refers to previously peer-reviewed evidence to support claims of reductions in salt content in foods. However, it is written by members of advocacy organizations and state organizations advocating for greater federal government action on salt reduction in Australia, therefore it should be interpreted on that basis. Alhamad N, Almalt E, Alamir N, et al. Cardiovasc Diagn Ther. 2015;5:172–177. Summary. The authors provide an overview of salt reduction activities to date in six Gulf Cooperation Council countries: Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates. Government initiatives to develop salt reduction implementation actions, primarily strategies to reduce salt in bread, are described. Current measurements of salt intake are 7 g/d to 8 g/d (sodium 2800–3200 mg; estimated based on spot urine) in Bahrain, 8 g/d to 10 g/d (sodium 3200–4000 mg; estimated based on dietary survey/food assessment) in Kuwait, and 11 g/d to 12 g/d (sodium 4400–4800 mg; estimated based on dietary survey) in Oman. Salt content in bread was assessed for different countries and ranged from 1.52 g salt/100 g (sodium 608 mg/100 g) in flat Arabic breads in Kuwait to 0.28 g salt/100 g (sodium 112 mg/100 g) in white bread in Jordan. The contribution of bread to total dietary salt ranged from 14.8% in Qatar to 53.9% in Morocco. All six countries have programs in place or are initiating programs to reduce salt in breads. The paper reports a 20% reduction in salt content in bread in Kuwait in 2013 and a 10% reduction in the salt content of bread in Qatar. All other countries are still in the early stages of implementation and have not yet reported reductions. No food labeling or consumer awareness initiatives are described. Comment. The paper reviews existing activities in six countries with a focus on government leadership and reducing salt in bread, which is a main contributor to salt intake in the region. The authors conclude that regional salt reduction efforts vary between the early stages of planning to an achieved 20% reduction in salt content of bread in Kuwait. The methods used to monitor the change in salt content of breads in Kuwait and Qatar are not explained, and therefore the strength of the evidence is unclear. The paper is also written by representatives of government ministries responsible for implementing the salt reduction strategies in their respective countries, therefore the study should be interpreted in that context. Almedawar MM, Nasreddine L, Olabi A, et al. Cardiovasc Diagn Ther. 2015;5:178–185. Summary. The authors provide an overview of the Lebanese Action on Sodium and Health (LASH) strategy led by an academic institution, which began by undertaking a situational analysis to prompt salt reduction action. Population salt intake was estimated to be between 7.25 g/d and 7.83 g/d (sodium 2900–3132 mg) from national dietary survey data. Processed foods, including bread (26%), processed meat (12%), and dairy products (9%), were found to be the major sources of sodium in the diet. In addition, the authors report poor KAB toward reduction in dietary sodium intake. Consumer campaigns were implemented, which provided educational materials such as shopping guides, posters, and information leaflets aimed at addressing the gaps in knowledge and changing behaviors. Ministry-selected food producers have agreed to undertake a pilot salt reduction initiative to reduce salt content in bread products, cured and In addition, has a number of to sodium in Comment. The paper reports strategy to reduce sodium intake in which has in government action to reduce salt in some on salt and sources of salt in the were measured through a nationally representative dietary the assessment of salt intake is likely to be an of the to and the reporting of salt the are in informing on the approach to reduce salt intake. Current consumers' KAB related to salt was measured in a sample of recruited from in results were used to the development of the strategy. The authors are representatives of which developed the salt reduction therefore should the study within this context. However, the to reduce sodium intake in to be by the et al. Summary. The survey measured sodium and in a of from the which included a sample by and for each of Sodium intake was estimated by a single 24-hour urine from each with samples excluded. A sample of was included in the the daily salt intake was 9 g and the was were used to assess by and Results showed that there was significant regional with in the of was in the and of by was also identified with in lower defined by and educational of and and was lower in with lower educational Comment. This large study includes a representative sample of from and estimates sodium and intake using the 24-hour urine The including of collections based on urine volume and is with guidelines by and there to be risk of bias. The that salt intake is in is in with studies from other and the of salt reduction initiatives that et al. Summary. The study estimated the daily salt intake in using the Health and for study from to 2011 in to years. The survey is made of a sample from population and from a study in The study sodium and measurements from spot urine samples collected in and estimated 24-hour sodium by the sodium to by and 24-hour were from the which 24-hour urine samples from to in and on this the estimated salt intake in was 10 g/d and g/d in A total of of and of in the nationally salt intake of Comment. The study estimated salt intake in the population from a large survey of made of a sample from population and is likely to be The study collected 24-hour urine from a representative from a national survey and on 24-hour urine volume and were made to the and 24-hour which were used to the 24-hour sodium from spot Although the standard 24-hour urine was not the large sample and the of the by using spot samples, it is likely to be a of the salt intake in The study that of the population likely the daily salt intake by a and a national salt reduction strategy is to population et al. Summary. This study the in the sodium content of processed foods in between and using two cross-sectional The study collected of food categories that were major of sodium in the from four major in in and two major in in 2013 The on sodium content were from on product The study found no significant in the sodium content of all collected foods in and In addition, there were products that were for in both which were using There was no significant in the mean sodium content of these products mg/100 g in and mg/100 g in Comment. This study showed no change in the sodium content of processed foods between and It is unclear how the in and 2013 in different or how they the food in information was not included in the analysis and have provided additional Sodium were from which is a method of data. some by the study provides information about the mean sodium content of products and foods on which to reformulation The study also the for efforts to lower the salt content in foods in B, Dunford E, et al. Summary. The authors the sodium content of products against products in four major in The study collected for food categories that salt in 2011 and 2013 The on sodium content were from the on product and mean sodium in and products were (1) all products in (2) products in both 2011 and and (3) products in using and The study found that the mean sodium content of products was lower than products by in all products in 2013 and in products in There was a significant than in the mean sodium content of both and products between 2011 and There was no significant in the change in sodium content between and products during this period. Comment. This study showed that products lower sodium content than products and that there been a but significant reduction in the sodium content of both and products during the study period. The large number of products collected from all four of the major that they are representative of products in Australia and that the study likely provides a over Sodium were from which is a method of data. However, there was no of which have provided the likely effects of the on population the main that products sodium than products is and the of further to how these can be to L, et al. Cardiovasc Diagn Ther. Summary. This study the sodium content of processed food products against the maximum set by the national in as a baseline against which the implementation can be were collected from food from a in in using a A total of products be and against maximum set by the national Results showed that maximum have been by of the food of food categories sodium content the and of the products the maximum Comment. This study showed that of the products collected in the survey were in with the salt targets. However, it is unclear whether the foods collected for analysis from one large are representative of the entire food in The of a with quality is a method of data. the of to the sodium content of the food with the targets is a as it is to and therefore can the sodium content per food The study was to monitoring and provides a baseline assessment of with the national salt as well as that the salt to be set lower to drive significant change in salt intake. N, et al. Summary. This study the between salt intake estimated from spot urine samples and awareness of guidelines for reducing salt intake in A sample of who the cardiovascular of was in the The were a questionnaire which level of salt awareness they or salt intake was estimated by a spot urine sample to which was The study found that salt intake was g/d in and that awareness of the guidelines did not with estimated daily salt intake. Comment. The study was in a sample of from one were to report their and single spot urine samples were used to salt intake, therefore the results are to be representative and to a high risk of bias. There is also no of for these which are by the the results are in with studies which found that knowledge is not with salt intake in This in with the that salt intake in is the is and the for greater efforts to salt intake and J, Summary. The modeling study the of two salt reduction strategies on population salt intake in the (1) the sodium content of processed foods to the and (2) changing consumers' behaviors to within the same food Food intake were from the National Food and sodium content in foods were from the 2011 Food In the where sodium content was to the reductions in sodium ranged from in to in to a reduction in population salt intake. In the food be with a with in a reduction in salt intake from processed foods. Comment. This study demonstrates that be achieved by reducing sodium content in a of processed foods to their or to The food and national food survey used to potential sodium reductions are and of quality. The food survey collected from a nationally representative using two 24-hour dietary However, no were to the of or the of these estimates on potential sodium reductions. of sodium were based on and a number of criteria set by the The potential in these in a was by the results with the of the reformulation intervention in the United where sodium reductions were achieved in food The authors also that major efforts were from the food industry to achieve the reductions. The scenario of foods with the within the same food is by the authors to be in that it is that all foods within a with that has the sodium The of this modeling study provide information about the to which a of processed foods to be or consumers' food choices to be improved to achieve a reduction in population salt intake. This review June to October identified 11 studies that can the future implementation of interventions to lower population salt intake. studies provided a overview of national programs to reduce salt intake and one included a pilot study that demonstrated the feasibility of reducing salt intake and KAB in in Mongolia. of the studies evaluated the impact of salt reduction strategies on population-wide salt intake. The four review studies were by advocacy or government organizations in the respective strategies about what and information the development of included in the reviews different to reducing salt Gulf Cooperation Council countries have their efforts on reducing the salt content in bread, has implemented health education and advocacy and Australia has a recommendations from the the of government and industry salt reduction. from reviews of salt reduction initiatives that is likely on a which includes both such as reformulation in an of food in with interventions that change consumer The of not on consumer interventions is demonstrated in the study by and which found no significant between knowledge of salt guidelines and measured daily salt intake in in the modeling study demonstrates the large reductions in salt content that to achieve or the dietary to in order to achieve the salt intake the interventions were implemented further the for that the in of salt intake, salt content of foods, and consumer KAB related to salt not to strategy development but also provide a basis against which can be studies in and found that population salt the daily maximum of 5 the for greater efforts to reduce salt 20 In addition, the study of salt intake in showed that intake was in which further the of implementing interventions that are more likely to all In countries, processed foods are the main of salt in the and therefore reformulation efforts are a key studies measured salt content in foods in Australia, and based on The study on salt content in foods in not provides an baseline to the of the salt targets but also identifies that products with the maximum that lower targets will to be set in the The study in Australia found that the mean salt content of foods was lower with foods, which the feasibility of products and the for products to greater efforts to reduce In there has been action to reformulation toward salt targets but no significant about the approach also the of monitoring mechanisms to determine whether reformulation activities are an Australia, and are all part of Food initiative to monitor the content of processed foods which has for robust that can be in other The 11 implementation studies are in and study design but provide recommendations for the implementation of salt reduction strategies. government implementing interventions than consumer and using to monitor the salt content of processed foods. All one study are from countries, the for greater and support for the implementation of programs to reduce salt in and countries, where four of every from cardiovascular causes are estimated to The to provide on the of sodium is by the World WHO on Population Salt Institute for Health Health Organization on through and World Action on Salt and have no of to and are authors on some of the studies included in the is a of World Action on Salt Health a dietary salt reduction but has no to is a with Institute and for is of the of World Action on Salt and and have from the World Health and National Health and Council of Australia for on salt reduction. is of the World Health Organization on Population Salt and is by a National Health and Foundation on strategies to reduce salt. The is not responsible for the content or of supporting information by the than should be to the for the