The invention is directed to seed and seed extract compositions containing levels of a human milk protein between 3-40% or higher of the total protein weight of the soluble protein extractable from the seed. Also disclosed is a method of producing the seed with high levels of extractable human milk protein. The method includes transforming a monocotyledonous plant with a chimeric gene having a protein-coding sequence encoding a protein normally present in human milk under the control of a seed maturation-specific promoter. The method may further includes a leader DNA sequence encoding a monocot seed-specific transit sequence capable to target a linked milk protein to a storage body.