The role of flaxseed lignans in hormone-dependent and independent cancer

Over the last 20 years, there has been a growing interest in the role of phytoestrogens – plant-derived compounds with estrogenic activity – in health and disease. The major classes of phytoestrogens examined are the isoflavones, coumestans, and lignans found at high levels in soybean, clover, and flaxseed, respectively (Rickard and Thompson, 1997). Lignans, the focus of this chapter, are diphenolic compounds that generally have a 2,3-dibenzylbutane skeleton (Ayers and Loike, 1990). They are believed to be by-products of the pathway for lignin synthesis (Setchell, 1995), and many have exhibited antibacterial, antifungal, and antimitotic activity (Ayers and Loike, 1990). These activities suggest that plant lignans are phytoalexins produced under stress which may play a role in the plant host-defense systems (Adlercreutz, 1998).