The study suggests that a salt-reduced diet improves the heart and kidney health of chronic kidney disease patients, potentially reducing the risk of disease progression by 30 per cent.
UQ School of Human Movement Studies PhD student Emma McMahon has monitored 20 people with chronic kidney disease on a high-salt diet and the same number on a low-salt diet.
The high-salt diet consisted of 4,600mg of sodium per day for two weeks, with the low-salt diet involving 1,800mg per day for the same period.
Reduction in excess fluid
McMahon said the study measured various factors relating to heart and kidney health, including change in body fluid volume, blood pressure, and protein in the urine.
“We found that low salt intake reduced excess extracellular body fluid, a risk marker for heart disease and worsening kidney health, by 1 litre, on average,” she said.
“It also lowered blood pressure by 10/4mm of mercury, and cut protein excretion in the urine by half, without causing significant side effects.
“These are clinically significant findings, with this magnitude of blood pressure reduction comparable to that expected with the addition of blood-pressure lowering medication.
“These effects are larger than what you would expect in people without chronic kidney disease.”
Principal investigator Katrina Campbell said the study found that salt restriction could be an inexpensive, low-risk and effective way to reduce heart and kidney risk in patients with chronic kidney disease.
“If these findings are transferable to the larger population with chronic kidney disease 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,” said Campbell.
The study is scheduled for publication in the Journal of the American Society of Nephrology.
In an accompanying editorial, Cheryl Anderson and Jochim Ix of the University of California San Diego School of Medicine praised the researchers for providing important clinical trial data in support of current clinical practice consensus guidelines, noting that "this study makes us cautiously optimistic."
They added that larger studies with longer follow-up specifically designed and carried out in populations with chronic kidney disease are needed to help inform recommendations to both individual patients and policymakers.