DHA does indeed have the potential to cause the skin to darken to a browner shade. The change in color occurs only in the outermost cells of the epidermis, the outer layer of the skin. The change in skin color occurs because DHA reacts with amino acids, the building blocks of the skin protein keratin, of which the skin tissue is primarily made. When DHA comes in contact with these amino acids, it combines with them and forms molecules called melanoidins.