Reduction in Sodium Intake did not Impact Cardiorenal Biomarkers After 2 Years

Andrew Smyth, MB,BCh, BAO, MMedSc, PhD

While reducing salt intake could have short-term positive effects on blood pressure, new research suggests it would be likely impact cardiorenal biomarkers.

A team, led by Andrew Smyth, National University of Ireland Galway, examined a cohort of patients who were given advice on reducing salt intake over the course of a 2-year study.

The data was presented as a late-breaking clinical abstract during the 2022 American Society of Nephrology (ASN) Annual Meeting in Orlando.

Sodium Advice

Low sodium intake of less than 2.3 grams per day has long been a recommendation. However, there is not much known about the long-term feasibility and effects on biomarkers for individuals with moderate intake.

In a pair of phase 2b, randomized, open-label, controlled, single-center trials, the investigators looked at individuals younger than 40 years with stable blood pressure, without heart failure, or postural hypotension. Each patient was randomized to an intensive dietary counseling intervention with a low sodium intake target or usual care.

The STICK trial focused on chronic kidney disease, while the COSIP study excluded individuals with CKD or cardiovascular disease.

Each participant received health eating advice.

There were a total of 373 individuals in the study with a mean sodium excretion of 3.1±1.5g/day.

Outcomes

The investigators sought primary outcomes of NT-pro B-type natriuretic peptide (NT-proBNP), high sensitivity troponin T (hsTnT), C-reactive protein (CRP, renin, aldosterone, and creatinine clearance (CrCl) at 2 years.

At the 2 year mark, the intervention group saw a significant reduction in self-reported salt use (73% vs. 41%; P <0.001), However, the same was not found for 24-hour urine sodium (intervention -0.23g/day vs. usual care +0.05g/day, P = 0.47).

At 3 months, the intervention group saw a reduction in blood pressure (systolic -2.52mmHg, P = 0.05; diastolic -1.92, P = 0.02) and increased renin (+33.35; 95% CI, 3.78-62.91).

This represents a big chance as there was no between-group differences in systolic blood pressure (P = 0.66), diastolic blood pressure (P = 0.09), NT-proBNP (P = 0.68), hsTNT (P = 0.20), CRP (P = 0.56), renin (P = 0.52), aldosterone (P = 0.61), or CrCl (P = 0.68) at 2 years.

“Among individuals with moderate intake, intensive dietary counselling resulted in short-term reductions in sodium and BP, but no significant effects on cardiorenal biomarkers at two years. Our trial suggests it may not be feasible to sustainably reduce sodium to guideline levels through intensive dietary counselling,” the authors wrote.

The study, “Dietary Counselling to Reduce Moderate Sodium Intake and Cardiovascular and Renal Biomarkers: Primary Findings of the COSIP and STICK Trial,” was published online by ASN.