A comprehensive strategic plan for sodium reduction will require a robust surveillance strategy to monitor key sodium indicators, evaluate progress and impact and optimize the plan over time. Data should be made publicly accessible in order to ensure transparency and hold the government accountable to its goals.
- Packaged foods
- Food prepared outside the home
- Sodium added in the home
- Appendices & Acknowledgments
- 5 Develop Surveillance, Monitoring and Evaulation Plans
Collect Sodium Indicator Data
- 7 Program Transparency and Accountability
- 8 Regular Program Review
Develop Surveillance, Monitoring and Evaulation Plans
A surveillance, monitoring and evaluation plan should establish ways to measure progress toward the goals outlined in the strategic plan (Section 1), including:
- Baseline and follow-up measurements of average population sodium intake
- Major sources of dietary sodium and the levels of sodium in foods targeted by the program
- Monitoring of interventions, which can include process indicators to monitor whether actions have been implemented in the timeframe outlined in the operational plan
- Interim indicators, such as the knowledge, attitudes, and practices (KAP) of segments of the public, which can contribute to monitoring program progress, barriers, or facilitators (see Section 6E).
The plan should outline the frequency of measuring key indicators and should include the required budget, the necessary research and laboratory capacity, and the steps required to build capacity if needed. It is ideal to assess all population indicators in a representative sample with adequate statistical power to examine changes over time and among specific sub populations of interest (e.g., different ethnic populations who may have unique dietary patterns, men vs. women, and key age groups).
Initiatives to reduce dietary sodium can begin while baseline data is being collected, provided the major sources of dietary sodium are known (understanding that the intervention may impact the baseline data).
Surveillance, monitoring, and evaluation plans are often developed and overseen by the sodium reduction advisory or working group; however, in many cases academic institutions or other research groups may be involved. It may be useful to have an independent group conducting surveillance activities. Surveillance of sodium intake and sources of salt can also be built into regularly schedule population surveys, such as WHO STEPS survey or the Demographic and Health Surveys. Additionally, ongoing monitoring and evaluation can be built into existing systems, for example, within health services or food safety systems.
The checklist in Appendix 1 can be used to structure a regular program review
Collect Sodium Indicator Data
The Surveillance, Monitoring, and Evaluation Plan (Section 5) will outline indicators that should be established at baseline and repeatedly measured throughout and after interventions take place. This section describes the key indicators to measure, including mean sodium intake; dietary sources of sodium; sodium content in packaged foods; iodine intake and fortification levels; and knowledge, attitudes, and practices related to sodium.
Establish mean daily sodium intake
Mean dietary sodium provides information on intake relative to the WHO recommended maximum adult intake of 2,000 mg of sodium (5 g salt) per day and sets the baseline for measuring future progress. Assess sodium intake through a nationally representative, adequately powered survey.
Several different methodologies can be used for measuring mean daily sodium intake. While more expensive and labor-intensive than other methods, the most accurate method is to collect complete 24-hour urine samples and analyze them for sodium and creatinine. (Although single 24-hour urine collections are not a reliable indicator of an individual’s usual sodium intake, the method is accurate on a population basis if the urine collections are complete.).
Measurement of sodium and creatinine using spot urine samples can be used to estimate average population 24-hour sodium intake. This method is used as part of the WHO STEPS survey and is less expensive and technically much easier than 24-hour urine collection. While it appears to be an acceptable way to assess the average population sodium intake at a single time point, using spot urine samples to assess change in average population sodium intake over time is considered to be less reliable (though research is still ongoing). Spot urine samples also underestimate the distribution of sodium intake. Ideally, if using spot urine samples, there should be a validation sub-sample where 24-hour urine samples are collected.
Dietary recall surveys (e.g., one or more 24-hour recalls) are another option for measuring sodium intake. Validity is highly dependent on the recall ability of the respondents, completeness and accuracy of the food database used to support the survey, and it is an unreliable method for assessing sodium added during cooking or at the table. While sodium intake can be significantly underestimated using this method (especially where food databases are less reliable or large proportions of sodium are added at home, in cooking or at the table), one advantage of the dietary recall survey is that it also assesses the dietary sources of sodium and provides information that is valuable for other, complementary nutrition initiatives. In some cases, surveys also quantified sodium intake using food weighing methods (Du 2014).
Establish the main sources of dietary sodium
Dietary sodium is typically consumed from three distinct sources: sodium added to packaged food during manufacturing, sodium added to food consumed outside the home (e.g., restaurants, street food vendors, cafeterias/canteens), and discretionary sources (sodium added in the home, either during cooking or while eating). The main dietary sources of sodium are usually established by dietary recall surveys or food frequency questionnaires (FFQ). The validity of the survey results is highly dependent on the recall ability of the respondents and the accuracy and completeness of the sodium content of the foods in the database used to support the survey. It is important to have data for the sodium content in targeted primary sources of sodium in order to track reductions over time (in addition to broader data on population sodium intake). Developing and updating a database to track the sodium content of foods is important for tracking changes that may occur during the intervention. If the intervention is successful, there may also be changes in the main dietary sources of sodium.
If it is not possible to pinpoint the main dietary sources of sodium, understanding the main components of the diet (regardless of the sodium content) can help plan and prioritize interventions.
Identify the sodium content in key packaged food categories
Many of the well-defined, evidenced-based policies to reduce sodium intake focus on packaged foods. A crucial starting point for these policies is to establish a database including key categories of packaged foods and their sodium levels. The easiest way to build this type of database is to use the sodium content from nutrition labels. Appendix 3 provides guidance on developing a food database via visits to food retail stores. In some settings, most of the data can be collected efficiently from online sources, and commercial groups may sell data on the nutrient content of packaged foods. Various technologies have been developed to assist collection of packaged food label data, such as applications that allow for simpler in-person data collection (e.g., FLIP, FoodSwitch), web-scraping techniques (e.g., foodDB), or crowd-sourcing (e.g., FoodSwitch).
While the Food and Agriculture Organization and WHO’s Codex Alimentarius (“Codex”) recommends that sodium be required on packaged food nutrient declarations, many countries still do not require it. See Section 10A for specific recommendations on mandatory nutrient declaration labeling. In addition to collecting label data, it may be necessary to measure the sodium level of selected foods for monitoring; in some countries, labeled nutrient content can be inaccurate even if labeling is required. Government food authorities can also create a national database of packaged foods by making it mandatory for food industry to submit nutritional content (including sodium) of packaged foods when applying for product registration.
Establish the levels of iodine fortification and intake
Once a major global public health concern, iodine deficiency has been largely overcome in many countries by iodizing salt. The levels of iodine added to salt should be based on sodium intake in the population; more iodine can be added as sodium intake falls, allowing for optimum intake of both nutrients. Iodine fortification and sodium reduction programs are thus mutually compatible and should be coordinated wherever possible in terms of both advocacy and communication (to policymakers, the food industry and the public) and to program surveillance and evaluation.
Iodine intake can be monitored along with sodium, with particular attention to the populations most vulnerable to iodine deficiency: children and pregnant women.Iodine is typically assessed using spot urine samples but, like sodium, can be more accurately measured using complete 24-hour urine samples.
Assess public knowledge, attitudes and practices (KAP)
Assessing the public’s knowledge, attitudes and practices (KAP) relating to dietary sodium can help in the design and monitoring of behavior change and education programs and provides a baseline of the public’s receptivity to and support of potential policy interventions. The result of repeated KAP surveys can be used to track the effectiveness of mass media campaigns, educational interventions and policy changes. However, monitoring changes in practice through KAP indicators cannot replace a quantitative assessment of sodium intake; many projects have seen changes in KAP survey indicators without changes to sodium intake.
KAP surveys can also be designed to assess the food industry’s knowledge, willingness and intention to change, the support or challenges from the health and scientific sector and from policymakers.
Innovative methods: household budget surveys to assess sodium intake and sources
A small number of countries (Brazil, Poland, Slovenia, and Costa Rica) have used Household Budget Surveys (HBS) to estimate average sodium consumption and major dietary sources of sodium. The method is rapid and inexpensive, with most countries collecting data through HBS every 4-5 years. There is inadequate research at this time to assess the generalizability or reliability of using this approach.
Program Transparency and Accountability
Once established, indicators for reducing dietary sodium should be made easily and publicly accessible to encourage transparency and accountability for the program. Making data available to the health and scientific community for analysis and dissemination applies pressure on the food sector to meet sodium targets in their products and on program leaders to meet overall program goals. Consumer protection groups can play an important role in ensuring accountability through communications with the public.
Regular Program Review
Sodium program operational plans (Section 1D) need to be reviewed and adjusted to account for lessons learned. Regular program review (e.g., annually) by the working group or other body identified in the strategic plan should assess progress towards targets and also take into account overall trends in dietary intake and sources.
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