Less Salt Lowers Blood Pressure in Kidney Disease Patients

In a study of patients with chronic kidney disease (CKD), simple advice from dietitians on limiting salt consumption led to reduced blood pressure. The findings, which appear in the Clinical Journal of the American Society of Nephrology, point to a practical way to potentially improve the health of patients with CKD.

Individuals with CKD often have hypertension and volume expansion, an increase in the total amount of fluid present in the body that often occurs when people take in too much salt (sodium) or have impaired kidney function. Increasing the amount of fluid in the body directly raises blood pressure.

Reducing volume expansion and blood pressure are important for slowing the rate of CKD progression. To see if a sodium-restricted diet might help achieve this, Rajiv Saran, MD, of the University of Michigan in Ann Arbor and colleagues conducted a randomized crossover trial. A total of 58 adults with CKD followed a sodium-restricted diet (<2 g of sodium per day) or their usual diet for four weeks, followed by a two-week washout period and then a four-week period when patients crossed over to the other diet. During the sodium restriction phase, patients didn't eat prepared low-sodium meals; rather, dietitians provided counseling every two weeks using motivational interviewing techniques.

In 79% of participants, dietary sodium was reduced during the restriction phase, and 65% of patients reduced their intake by more than 20%. During that time, patients experienced an average reduction of 11 mm Hg in systolic blood pressure and an average reduction in volume of 1 L.

"We found that reducing sodium in the diet helps to significantly reduce blood pressure and reduce the excess fluid retention that is common among patients with kidney disease," Saran says. "This did not require complicated precooked meals and was simply based on commonsense advice given by trained dietitians that helps patients understand what it takes to reduce salt in their diets and what the potential benefits are likely to be." Saran notes that, if applied diligently, sodium restriction may help patients take fewer blood pressure medications.

— Source: American Society of Nephrology