A diet with restricted salt intake may help to reduce the risk for cardiovascular disease in patients with chronic kidney disease (CKD), as well as the risk for CKD progression, according to an article published online November 7 in the Journal of the American Society of Nephrology.
Emma J. McMahon, PhD candidate, University of Queensland, Australia, and colleagues conducted a double-blind, placebo-controlled randomized crossover trial involving 20 adult patients with stage 3 to 4 CKD. In the phase I portion of the LowSALT CKD study, the researchers evaluated the effects of high vs low sodium intake on several physiological measures, including ambulatory blood pressure, protein excretion, and body fluid status.
The researchers counseled patients to eat a low-sodium (1080 – 1440 mg/day) diet during the 1-week run-in period of the 6-week study, they then randomly assigned patients to either a high-sodium or low-sodium diet. Those on the high-sodium diet had a goal of 1080 to 1440 mg/day plus 2160 mg/day from a slow-release tablet. Those on the low-sodium diet had a goal of 1080 to 1440 mg/day plus a placebo capsule. Patients crossed over after an intermediate washout week.
The investigators found a mean reduction of 9.7/3.9 mm Hg in blood pressure in patients on the low-salt diet compared with the high-salt diet. The reductions were consistent during a 24-hour period with no significant difference between daytime and nighttime measurements. Researchers also found that patients had reductions in fluid volume, body weight, and protein in the urine while on the low-salt diet.
“If these findings are transferable to the larger CKD population and shown to be sustainable long-term, this could translate to markedly reduced risk of cardiovascular events and progression to end-stage kidney disease, and it could generate considerable health-care savings,” senior author Katrina J. Campbell, PhD, from Princess Alexandra Hospital, Queensland, said in a news release.
“These are clinically significant findings, with this magnitude of blood pressure reduction being comparable to that expected with the addition of an anti-hypertensive medication and larger than effects usually seen with sodium restriction in people without CKD,” McMahon noted in the release. “If maintained long-term, this could reduce risk of progression to end-stage kidney disease — where dialysis or transplant is required to survive — by 30%.”
“This study is salient because few intervention studies have evaluated dietary sodium reduction in patients with CKD, write Cheryl A.M. Anderson, PhD, MPH, and Joachim H. Ix, MD, both from the University of California San Diego School of Medicine, in an accompanying editorial. “The evaluation of other outcomes in addition to BP is an additional strength of the trial.”