Dietary therapy may benefit patients with advanced chronic kidney disease (CKD) transitioning to renal replacement therapy (RRT) or actually in need of RRT, according to the authors of a new review published in the Clinical Journal of the American Society of Nephrology.
Tailored renal diets potentially reduce the retention of sodium, potassium, phosphorus, acids, and water that contributes to harmful states, including oxidative stress, edema, heart failure, hyperkalemia, hyperphosphatemia, metabolic acidosis, and hyperparathyroidism.
Much research has centered on delaying CKD progression with diet. Still other benefits are possible, according to investigators Norio Hanafusa, MD, Bereket Tessema Lodebo, MD, and Joel D. Kopple, MD, of Los Angeles Biomedical Research Institute at Harbor–UCLA Medical Center in Torrance, California. Low protein diets (LPD) with a daily protein intake of 0.6-0.8 g/kg/day and ketoacid or essential amino acid supplemented very low protein diets (SVLPD) might delay dialysis initiation by reducing uremic toxicity. High average protein intakes of 1.03 and 0.99 g protein/kg/day have been reported for male and female patients, respectively, in the United States. Yet a 2007 study by Giuliano Brunori et al. published in the American Journal of Kidney Diseases found that some elderly patients assigned to SVLPDs for 10.7 months safely delayed dialysis initiation. Eventually, 71% of these patients started dialysis due to fluid overload or hyperkalemia.
Dietary therapy also may delay thrice-weekly dialysis and permit incremental or infrequent dialysis for patients with residual renal function, the authors suggested. Well-designed LPD and SVLPD possibly reduce the production and accumulation of toxic solutes in kidney failure.
“These findings strongly suggest that dietary therapy can be used to safely delay (for up to several months) the need for chronic dialysis in selected patients with pre-ESRD,” the authors wrote. “LPDs or SVLPDs may also provide patients with advanced CKD with sufficient time for placement and maturation of a permanent hemodialysis vascular access or peritoneal dialysis catheter without requiring the use of temporary catheters needed to inaugurate dialysis urgently.”
Finally, an obvious but important goal of kidney-friendly diets is preventing malnutrition. Renal diets need to be crafted to avoid protein-energy wasting. Patients also need adequate energy intake, along with sufficient calcium, trace elements (e.g., iron, zinc, selenium), and vitamins, particularly vitamin B6, folate, vitamin C, cholecalciferol, and 1,25-dihydroxycholecalciferol.
The authors encouraged more research, including randomized clinical trials, to answer outstanding questions on designing and implementing optimal renal diets.