Adding Salt to Food More Frequently Can Increase Risk of Premature Death

Lu Qi, MD, PhD

Reducing the amount of salt a person adds to their foods could have a significant impact on the risk of premature mortality in adult patients, according to a new analysis.

An analysis of nutrition questionnaire data from more than 500,000 patients in the UK Biobank study, results of the study suggest those with the greatest frequency of adding salt to foods were at a 28% increase in risk of premature death, but also provided evidence suggesting consumption of fruits and vegetables significantly modified this apparent association.

“To my knowledge, our study is the first to assess the relation between adding salt to foods and premature death,” said Lu Qi, MD, PhD, of Tulane University School of Public Health and Tropical Medicine, in a statement. “It provides novel evidence to support recommendations to modify eating behaviors for improving health. Even a modest reduction in sodium intake, by adding less or no salt to food at the table, is likely to result in substantial health benefits, especially when it is achieved in the general population.”

With an interest in understanding how modifying salt intake might influence risk of mortality, Qi and a team of colleagues conducted the current study with the aim of assessing how frequency of adding salt to foods and the hazard of premature mortality and life expectancy. To do so, investigators designed their study as an analysis of data from within the UK Biobank study, which provided them with data from 501,379 participants that were included in their main analysis.

As part of the UK Biobank study, participants were asked if they added salt to their foods during a questionnaire at baseline, with 5 potential responses: never/rarely, sometimes, usually, always, and prefer not to answer. For the purpose of analysis, those who elected prefer not to answer were assigned to missing values. Instances of premature death were ascertained through a review of death certificates held by the National Health Service Information Centre for participants in England and Wales and the National Health Service Central Register Scotland for participants from Scotland.

During a median follow-up period lasting 9.0 years, 18,474 premature deaths occurred in the study cohort. Upon analysis, results indicated the risk of all-cause premature mortality increased as the frequency of adding salt to foods increased, with multivariable hazard ratios of 1.02 (95% CI, 0.99-1.06), 1.07 (95% CI, 1.02-1.11), and 1.28 (95% CI, 1.20-1.35) (P-trend <.001) among those reporting sometimes, usually, and always adding salt to their foods, respectively. Further analysis suggested intake of fruits and vegetables significantly modified the associations between adding salt to food and risk of premature mortality, which investigators noted were more pronounced in those with low stakes those with high intakes of these foods (P-interaction=.02). Investigators also pointed out those reporting always adding salt to foods had 1.50 (95% CI, 0.72-2.30) and 2.28 (95% CI, 1.66-2.90) years lower life expectancy at the age of 50 years in women and men, respectively, when compared to those reporting never or rarely reporting adding salt to their foods.

In a linked editorial accompanying the study, Annika Rosengren, professor of medicine at the Sahlgrenska Academy at the University of Gothenburg, commended investigators for their work and noted how reducing salt, either as an additive or as part of an overall salt-reduction strategy, should still be viewed as a cornerstone of prevention.

“The obvious and evidence-based strategy with respect to preventing cardiovascular disease in individuals is early detection and treatment of hypertension, including lifestyle modifications, while salt-reduction strategies at the societal level will lower population mean blood pressure levels, resulting in fewer people developing hypertension, needing treatment, and becoming sick,” Rosengren wrote. “Not adding extra salt to food is unlikely to be harmful and could contribute to strategies to lower population blood pressure levels.”

This study, “Adding salt to foods and hazard of premature mortality,” was published in the European Heart Journal.