A composition comprising (a) milk or a crude protein-containing extract thereof； (b) a fatty acid or a lipid or a salt thereof； and (c) an acidifying agent in an amount that is sufficient to reduce the pH of the composition to less than 4； wherein the composition has been heat-treated. Compositions of the invention have biological activity in particular in the treatment or prevention of gastrointestinal cancer, and so use as nutraceuticals or pharmaceuticals.
