[Nutrition for patients on dialysis]

Dietary recommendations for patients on dialysis are changing as our understanding of enteral microbiotal metabolism and bioavailability of nutrients from food improves.A diet low in phosphate and potassium is recommended for patients on hemodialysis. However, the absolute content does not reflect bioavailability: How much phosphate or potassium is taken up depends on food source (plant vs. animal) and to which grade it is processed. While both are nearly 100% bioavailable from industrially processed foods (additives such as dipotassium-phosphate and other salts), a much lower proportion is taken up from unprocessed plant foods high in fibre (ca. 20-40%). The DIET-HD study showed no significant association between dietary potassium and serum potassium in > 8 000 dialysis patients; and those with the highest low-processed, fresh plant-food consumption have the best survival. Dietary fibre improves colon transit time and thereby lessens symptoms of constipation. A diet low in sodium improves blood pressure and volume management in dialysis patients. The energy and protein requirements on dialysis are high: 25-35 kcal and 1-1,2 g protein per kg body weight per day (in relation to "ideal" body weight, if patient is overweight). Protein energy wasting is associated with higher stages of kidney disease, and malnutrition is associated with worse survival on dialysis. Nutritional status should be assessed on a regular basis using validated scores, and malnutrition should be addressed and treated.