Sodium, added sugar and saturated fat intake in relation to mortality and CVD events in adults: Canadian National Nutrition Survey linked with vital statistics and health administrative databases

Traditionally, studies on the association between Na, saturated fat, and sugar intake and all-cause mortality or CVD events have been prospective cohort studies of middle-aged or older adults^(1–3). Some major limitations of previous studies include the use of single FFQ⁽⁴⁾, sample selection bias or lack of generalisability, random and systematic measurement errors⁽⁵⁾, and using dichotomised dietary exposure data (linearity assumption). The latter is critical because these nutrients, particularly Na, are generally consumed more than the standard recommended amounts in Canada⁽⁶⁾ and the USA⁽⁷⁾.

To our knowledge, no previous study globally has examined the association of Na, added sugar and saturated fat with CVD incidence and mortality using large-scale nationally representative nutrition surveys linked with health administrative databases (particularly with regard to CVD outcomes). The concept of a dose–response relationship between nutrients and mortality or CVD events needs further elucidation, especially in countries following Western-type dietary patterns. This is important as nutrition policymakers may-face barriers in policy development because of mixed messages coming from research studies.

Herein, we present results on the association between Na, added sugars and saturated fat with both all-cause mortality and CVD events using the large scale national nutrition survey (Canadian Community Health Survey-Nutrition 2004 (CCHS-Nutrition 2004)) that is linked at the individual level to health administrative databases, the Canadian Vital Statistics – Death Database (CVSD) and Discharge Abstract Database (DAD) (2004–2011). Our secondary goal was to evaluate whether such large-scale linked national nutrition datasets are discriminatory enough to tease out the prospective impacts of nutrients on objective health measures (i.e., all-cause mortality and CVD mortality and incidence) and whether other foods and nutrients that are highly correlated with Na, added sugars and saturated fat can modify the relationship between these three nutrients and health outcomes. This study addresses potential limitations of previous research using a national-level survey, using outcomes linked to health administrative rather than self-reported data, using repeated 24-h recalls rather than FFQ, addressing dietary misreporting and by conducting sensitivity modelling.

Methods

Study population and design

This study was conducted according to the guidelines laid down in the Declaration of Helsinki, and all procedures involving research study participants were approved by the Ottawa Health Science Network Research Ethics Board. Data were...