VITAMINS The loss of water soluble vitamins associated with dialysis is partly counteracted by the loss of renal function, which decreases their catabolism. Dietary manipulation, even if aimed at controlling potassium and sodium intake, may lead to clinically relevant losses of some vitamins. Routine supplemen- tation of vitamins involved in iron and calcium metabolism is common in dialysis patients; other vitamins should be pre- scribed only when necessary (EDTNA/ERCA 2002).