Sodium: it is in most of the foods we eat - a lot in some and a little in others. How much sodium do you consume each day?
Excess dietary sodium increases blood pressure and is a risk factor for hypertension (high blood pressure), cardiovascular disease, stroke and kidney disease. Dietary sodium reduction is a public health priority to address the burden of hypertension and cardiovascular disease. In many countries, including Canada, populations consume sodium in amounts over the World Health Organization’s recommendation of <2000 mg sodium/day. Many people have misconceptions and a lack of awareness about the amount and sources of sodium in their diet. There are few known tools available to assess sodium in the diet, however, none of these tools provide timely, personalized feedback. Therefore, we developed a web-based sodium intake screening tool called the Sodium Calculator, which is publicly available for individuals to rapidly assess the amount and sources of sodium in their diet.
The Sodium Calculator questions were developed by examining sources of sodium in the diet using the 2004 (n = 35,107) and 2015 (n = 20,487) cycles of a nationally-representative, population nutrition survey—the Canadian Community Health Survey (CCHS)-Nutrition. CCHS-Nutrition is a multi-stage clustered design representative for age, sex, geography and socioeconomic status, and provides detailed information at the national and provincial levels on food consumption for respondents using a 24-hour dietary recall. Using the CCHS-Nutrition, the Sodium Calculator questions were prioritized considering the sources and the amount of sodium for various age and sex groups, the total food group contribution and proportion of individuals who reported consuming a given food. The sodium content (mg/100g) of foods and beverages that made the greatest contribution to sodium intakes were collected and combined using the University of Toronto Food Label Information Program (FLIP) 2013/2017 and the Canadian Nutrient File 2010/2015. FLIP is a branded food composition database of 10,487 (2013) and 16,761 (2017) packaged foods, whereas the Canadian Nutrient File is the national food composition database of 5,807 (2010) and 5,690 (2015) foods maintained by Health Canada. The University of Toronto Restaurant-FLIP was used to derive the sodium content of fast-food and restaurant foods (n=4,836 (2013), and n=12,271 (2016)). Foods were classified into sodium-focused categories that included food groups (e.g., bakery), major (e.g., bread) and minor (e.g., bagels) sub-categories. As part of the development process, all questions were tested among nutrition experts and health-care practitioners for content and face validity, and the general public for usability and interface testing. The Sodium Calculator has been validated as a method of estimating dietary sodium intake in young adults (aged 18-35 years) and is currently undergoing validation in adults with high blood pressure.
The Sodium Calculator consists of 26 questions to capture how often sodium-containing foods are consumed, including sub-questions on packaged foods (n=20), restaurant foods (n=5) and one on added salt. It takes <5 minutes to complete. In order to estimate the amount of sodium consumed from the different food categories, the SC uses algorithms (behind the scenes calculations) based on average portion sizes consumed by 13 age and sex groups, as reported in the CCHS: all 4-8 years, and males and females 9-13 years, 14-18 years, 19-30 years, 30-51 years, 51-70 years and 71 years and older. Median sodium levels were derived from the FLIP and Canadian Nutrient File databases and were weighted according to the number of products in the food sub-category. Correction factors of 20% for packaged foods and 10% for restaurant foods were applied to the derived sodium estimates to approximate habitual sodium consumption. A detailed report for users is generated based on responses to the SC. This report provides information on the estimated average amount of sodium consumed per day and compares it with the Dietary Reference Intake levels that correspond to the user’s age. Additional information in the report includes the relative percent contribution of sodium coming from restaurant foods, using added salt and distinct food categories to total sodium intake. The report also communicates the risk of high dietary sodium consumption in relation to risk of cardiovascular diseases and provides resources to users on strategies to lower dietary sodium. Evidence on the risk of high dietary sodium intake in relation to cardiovascular disease incidence was obtained from the Institute of Medicine Dietary Reference Intakes report (NASEM, 2019), which ensures the inclusion of high-quality studies (e.g. randomized controlled trial), free of co-interventions. The 27% risk reduction per g/day sodium intake reduction for cardiovascular disease risk was used
The Sodium Calculator provides users with rapid, detailed, personalized information on dietary sodium. The SC can potentially track changes in sodium intake over time and can also be used by healthcare practitioners to support behaviour change and improved health outcomes.
