Eliminating Phosphorus Food Additives Does Not Compromise Nutrition
Maintenance hemodialysis (HD) patients who substitute foods that contain phosphorus-based additives with similar foods free of these additives can reduce their hyperphosphatemia without compromising nutrition, a new study confirms.
Typically, hyperphosphatemia patients are advised to restrict foods naturally containing an abundance of organic phosphorus, such as meats, dairy products, whole grain cereals, legumes, and nuts. Organic phosphorus is 60% absorbed, whereas inorganic phosphorus in the form of food additives is 90% absorbed.
For their trial, Margareth Lage Leite de Fornasari, RD, PhD, and Yvoty Alves dos Santos Sens, MD, PhD, of Santa Casa of Sao Paulo School of Medical Sciences, Sao Paulo, Brazil, randomly assigned 134 patients with serum phosphorus levels above 5.5 mg/dL to intervention or control groups. At baseline, all were taught the standard kidney-friendly diet and the importance of dietary phosphorus restriction. Patients were interviewed individually about their nutrition and responded to a 24-hour dietary recall and food frequency questionnaire. To gauge their level of understanding, participants were quizzed about the renal diet. Patients kept a 3-day food diary that included 1 dialysis day, 1 nondialysis day, and a weekend. The investigators calculated the normalized protein nitrogen appearance to estimate patients' dietary protein intake.
The intervention group received additional support. Using the food label, patients were taught which foods contained phosphorus preservatives and needed to be avoided. A dietitian provided a list of substitutes, including preservative-free recipes, tailored to each patient and revised over time. For example, instead of store-bought dark cola, a patient might receive a recipe for homemade iced tea, and in place of cold cuts, a recipe for chicken breast or beef.
During the trial, prescriptions for phosphate binders and vitamin D therapy remained the same. No one received cinacalcet or calcium supplements.
Over 3 months, serum phosphorus levels declined in the intervention group from 7.2 to 5 mg/dL. But no significant difference was observed in the control group (7.1 to 6.7 mg/dL). More patients in the intervention group attained a goal serum phosphorus level of 5.5 mg/dL or below: 69.7% vs 18.5%. “Notably, the nutritional status of the subjects did not appear to change during the 3-month study although reducing phosphorus intake in clinical practice without compromising protein intake is difficult,” Dr Leite de Fornasari and Dr Alves dos Santos Sens wrote in the Journal of Renal Nutrition.
They found no reductions in body mass index, lean mass, or fat mass. Both protein and energy consumption were maintained. PNA stayed within the recommended level.
“This low-cost and simple intervention can be easily implemented by a renal dietitian. This study shows the importance of using individualized nutritional counseling among ESRD patients in combination with phosphate binders to reduce serum phosphorus levels,” the investigators stated.