Breast enhancement pills usually contain herbs (like Blue Vervain Herb), with natural estrogenic properties from plant sources (phyto-estrogens) that work by regulating hormones and promote healthy tissue growth. Breast enhancement supplements enhances and stimulates estrogen-sensitive breast tissues and helps to enhance breast size naturally by introducing phyto-estrogen (naturally occuring plant estrogen) derived from plants directly into the estrogen receptor sites.One of most commonly used herb in breast enlargement pills is Blue Vervain Herb. Blue vervain is a bristly perennial grown at the northern U.S. and Canada and also to be found in England. The quadrangular stem can climb up a height of 2 to 5 feet and have leaves that are opposite, serrate, and lanceolate with short leaf stalks. The flBlue vervain has been used as an antiperiodic, diaphoretic, emetic, expectorant, tonic, vermifuge, and vulnerary.