The invention relates to a serum protein product, suitable as an ingredient for foods and therapeutic compositions, in particular infant and baby foods. The invention also provides a method for the preparation of the serum protein product, based on micro filtration of milk. The invention provides a method for the preparation of a serum protein product, comprising the preparation of a permeate through micro filtration of cow's milk at a temperature of between 10 and 20.degree. C. utilizing a membrane having a pore size of between 0.3 and 0.5 .mu.m.