New compositions are disclosed that comprise the phytochemical Diindolylmethane (DIM), as well as its precursor, Indole-3-carbinol (I3C), and cogener, 2-(Indol-3-ylmethyl)-3,3'diindolylmethane (LTR-1), acceptable carriers and/or excipients. These compositions are administered to prevent or reduce symptoms associated with mastalgia and endometriosis.