Conflicting Dietary Advice for Adhering to Low-Sodium and Low-Phosphorus Diets

Abstract

To elucidate conflicts that patients face when advised to limit multiple nutrients in their diet. We analyzed the phosphorus content of low-sodium foods compared with their regular-sodium content counterparts, and the sodium content of low-phosphorus foods compared with foods containing higher levels of phosphorus. Low-sodium and low-phosphorus foods were identified with the use of recommendations from National Kidney Foundation patient information Web sites. Content of sodium and phosphorus was quantified with use of the US Department of Agriculture (USDA) Nutrient Database. Review and analysis of publicly available patient information Web sites and nutrient databases. Phosphorus content of low- versus regular-sodium-containing foods, and sodium content of low- versus high-phosphorus-containing foods. Of 47 low-sodium foods, 32 had identical phosphorus content--8 higher and 7 lower--compared with regular-sodium alternatives. Of 9 foods recommended as low-phosphorus alternatives to high-phosphorus choices, 4 had higher sodium content and 5 had lower, with considerable variability. However, choosing servings of 4 low-sodium alternatives could increase ingestion of phosphorus by up to 16% of recommended intake, and choosing servings of 4 low-phosphorus alternatives could increase ingestion of sodium by more than 20% of recommended intake. Adhering to a complex renal diet is extremely difficult for patients with chronic kidney disease. Balancing sodium and phosphorus restrictions is particularly challenging, especially as food choices low in one nutrient may not be low in the other. To help patients follow these diets, alternative methods of achieving dietary restrictions of multiple, often conflicting, components may be needed.