Daily Dose: Frequent Addition of Salt to Food Raises Risk of CKD

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Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

On January 5, 2024, we reported on findings from a study published in JAMA Network Open that examined the association of self-reported frequency of adding salt to foods with incident chronic kidney disease (CKD) risk in a general population of adults.

The study

Researchers conducted a population-based cohort study evaluated UK Biobank participants aged 37 to 73 years who were free of CKD at baseline. Participants were enrolled from 2006 to 2010 and prospectively followed up for disease diagnosis. The cohort included 465 288 individuals (average age 56 years), 54.8% of whom were women.

The main outcome was incident CKD, which was identified via ICD-10 codes. Salt intake was self-reported via a questionnaire where persons were asked if they added salt to food on a 5-point scale: never/rarely, sometimes, usually, always, or prefer not to answer.

Models were adjusted for age, sex, race and ethnicity, Townsend Deprivation Index, eGFR, BMI, smoking status, alcohol consumption, regular physical activity, diabetes, CVD, hypercholesterolemia, infectious disease, immune disease, and nephrotoxic drugs use at baseline.

The findings

Among participants from the UK Biobank who were free of CKD at baseline, compared with those who reported never or rarely adding salt to their food, those who sometimes added extra salt (adjusted hazard ratio [aHR] 1.04, 95% CI 1.00-1.07), those who usually added salt (aHR 1.07, 95% CI 1.02-1.11), and those who always adding salt to their food (aHR 1.11, 95% CI 1.05-1.18) had an increased risk of CKD (P for trend <.001) after researchers adjusted for covariates.

Furthermore, the associations were more pronounced among participants with a higher eGFR and lower BMI or exercise level.

Authors' comment

"These findings suggest that adding salt to foods is associated with increased risk of CKD in the general population, emphasizing the possible value of limiting discretionary salt to reduce CKD risk."

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