Abstract: The invention relates to a liquid or gelled pasteurized or sterilized composition comprising free amino acids, calcium, a digestible carbohydrate, and preferably an indigestible carbohydrate, wherein the free amino acids are present in a concentration between 5 and 30 g/100 ml, and the dry weight of the total composition is at least 40 g/100 ml, and preferably lower than 60 g/100 ml. The composition may in particular be used in the treatment of a human suffering from a disorder selected from the group consisting of phenylketonuria, homocystinuria, maple syrup urine disease, tyrosinaemia, propionic acidaemia, methylmalonic acidaemia, isovaleric acidaemia, urea cycle disorders and glutaric aciduria.