Lowering salt intake improves heart and kidney health of chronic kidney disease patients

Reducing salt intake provides clear benefits for the heart and kidney health of patients with chronic kidney disease, according to a study appearing in an upcoming issue of the Journal of the American Society of Nephrology (JASN). The findings point to the power of salt restriction in potentially prolonging kidney disease patients' lives.

Excessive salt intake is consistently linked to increased risk of heart disease and worsening function. People with (CKD) may be particularly susceptible to salt's detrimental effects due to the kidney's important role in controlling salt balance and their increased risk of dying from . Until now, though, the effect of in these patients has not been well explored.

The LowSALT CKD study represents the first blinded randomized controlled trial comparing a high vs low salt intake in people with CKD. During the study, Emma McMahon (PhD candidate, University of Queensland, in Australia) and her colleagues, led by principal investigator Katrina Campbell, PhD (Princess Alexandra Hospital, in Australia) compared the effects of a high salt diet (180 to 200 mmol/day) vs a low salt diet (60 to 80 mmol/day) maintained for two weeks each in a random order in 20 patients with CKD. (Dietary guidelines recommend limiting sodium to less than 100 mmol—which is 2300 mg or one teaspoon—per day.) The team measured various parameters related to heart and kidney health, including change in extracellular fluid volume, blood pressure, and protein in the urine.

The researchers found that on average, low reduced excess extracellular fluid volume by 1 liter, lowered blood pressure by 10 /4 mm Hg, and halved protein excretion in the urine, without causing significant side effects.

"These are clinically significant findings, with this magnitude of 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," said McMahon. She was particularly impressed with the 50% reduction in protein excretion in the urine. "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%."

The findings suggest that salt restriction is an inexpensive, low-risk and effective intervention for reducing cardiovascular risk and risk of worsening in people with CKD. "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 , and it could generate considerable health-care savings," said Dr. Campbell.

In an accompanying editorial, Cheryl Anderson, PhD, and Jochim Ix, MD (University of California San Diego School of Medicine) commended 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 CKD populations are needed to help inform recommendations to both individual patients and policymakers.

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More information: The article, entitled "A randomized trial of dietary sodium restriction in chronic kidney disease," will appear online on November 7, 2013, DOI: 10.1681/ASN2013030285

The editorial, entitled "Sodium Reduction in CKD: Suggestively Hazardous or Intuitively Advantageous?" will appear online on November 7, 2013, DOI: 10.1681/ASN.2013090923

Citation: Lowering salt intake improves heart and kidney health of chronic kidney disease patients (2013, November 7) retrieved 19 October 2019 from https://medicalxpress.com/news/2013-11-lowering-salt-intake-heart-kidney.html
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Nov 08, 2013
While all evidence contributes to our base of knowledge, it is useful to bring some perspective to an article such as this. Less than 0.5% of the population under age 60 and less than 5% of those over age 60 suffer from CKD. Along with other published data, this work stresses the need for greater attention to be paid to overall diet and lifestyle changes in our aging populations. Considering the relatively small cohort used in this study, the advice of Anderson and Ix to follow up with larger studies and longer duration is noteworthy. It would also be important to specifically highlight which side effects were examined, as several recent studies have demonstrated a wide range of negative health impacts associated with sodium reduction, including insulin resistance, changes to cholesterol and triglyceride profiles, etc.

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