Role of dietary phosphate restriction in chronic kidney disease

Background and objectives Patients with progressive chronic kidney disease (CKD) develop positive phosphate balance that is associated with increased cardiovascular risk and mortality. Modification of dietary phosphate is a commonly used strategy to improve outcomes but is complicated by the need for adequate dietary protein. Surprisingly, the evidence for patient-level benefits from phosphate restriction is tenuous, and the justification for using any phosphate binder for pre-dialysis patients is questionable. Design, setting, participants, and measurements We review the evidence for dietary phosphate modification and the possible role of a smart phone application (app.) that provides information on phosphate, sodium, potassium and nutrients in over 50,000 Australian foods. We performed a pilot study of healthy participants assigned to dietetic advice and standard diet sheets, or dietetic advice, diet sheets and use of the smart phone app. Results Following baseline studies, 25 participants commenced the sodium and phosphate restricted diet. After two weeks, both groups showed non-significant trends to reduction in urinary phosphate and sodium. App. users referred to information on the app. more frequently than the control group participants referred to written instructions, found referring to the app. more convenient, felt they learned more new information, were more motivated to maintain the diet and were more likely to recommend their information source to family or friends (all p<0.05), Conclusions Maintaining phosphate balance remains an important goal of CKD management, although diets incorporating very low phosphate and protein contents may worsen patient outcomes. For selected patients, a smart phone app. may improve dietary acceptance and compliance.