While there was a linear relationship between increasing sodium intake and blood pressure, there was not an association between sodium intake and an increased risk for cardiovascular events or deaths in participants at low-risk for cardiovascular disease, according to a study published in Hypertension.
Researchers used data from the UK Biobank to assess the relationship between sodium intake, cardiovascular disease, and death. The UK Biobank database provided information on patients’ demographic data, body mass index (BMI), smoking status, and diagnoses of diabetes mellitus, stroke, myocardial infarction, transient ischemic attack, and brain hemorrhage.
A urine sample was used to measure sodium and potassium excretion, and the estimated 24-hour excretion was calculated using the Kawasaki formula. The primary outcomes were all-cause mortality, cardiovascular death, and nonfatal cardiovascular event.
The 322,624 participants in this study were classified into quintiles based on mean arterial blood pressure and again based on estimated sodium excretion. Participants in the highest blood pressure quintile were older, had a higher BMI, and had a higher sodium excretion than the other quintiles. Patients in the highest sodium excretion quintile were younger, had a higher BMI, and had a higher mean arterial blood pressure than the other quintiles.
A regression model indicated a linear relationship between higher sodium excretion quintiles and higher blood pressure. During the median follow-up time frame of 6.99 years, there were 6724 all-cause deaths, 740 fatal cardiovascular events in men, 364 fatal cardiovascular events in women, 6972 nonfatal cardiovascular events in men, and 3739 nonfatal cardiovascular events in women. No association was found between sodium excretion quintiles and the risk for cardiovascular event or deaths or all-cause mortality.
Limitations of this study include the data being observational, which limited researchers in assessing causality. Additionally, potential sample biases due to volunteering participants, using a single urine sample to estimate sodium intake, and potential discrepancies between dietary sodium intake and sodium output were limitations.
The researchers concluded that “the relationship between increasing sodium intake and blood pressure is linear, but there is a fairly limited relationship between salt intake and risk of fatal/nonfatal [cardiovascular disease] and [all-cause mortality] in subjects at low cardiovascular risk.”
Welsh CE, Welsh P, Jhund P, et al. Urinary sodium excretion, blood pressure, and risk of future cardiovascular disease and mortality in subjects without prior cardiovascular disease. Hypertension. 2019;73(6):1202-1209.