A nutritional formulation comprises a blend of amino acids and is characterised by the presence of not more than 20 % by weight acetylmethionine, not more than 3 % by weight methionine, and not more than 0.1 % by weight glutamic acid, and a balancing percentage of other amino acids, the percentages being based on the total weight of the amino acids in the formulation. The formulation does not have off-flavours which have been found to be caused by the presence of methionine and glutamic acid in amounts greater than those indicated.