Secoisolaricircsinol is one of the most abundant dietary lignans in various foods, such as plant seeds, whole grains, legumes, vegetables, and fruits. Secoisolariciresinol is the major lignin found in flaxseed and is present in a polymer that contains Secoisolariciresinol diglucoside. Secoisolariciresinol and Secoisolariciresinol diglucoside are known to have a number of health benefits, including reduction of the serum cholesterol levels, delaying of the onset of type 2 diabetes, and reduction of the formation of hormone-sensitive cancers such as breast, prostate, and colon cancers. Following the consumption of Secoisolariciresinol diglucoside, it is further converted by the bacteria in the colon of humans and other animals into aglycone Secoisolariciresinol and the mammalian lignans, enterodiol and enterolactone. The structures of enterodiol and enterolactone are similar to that of estradiol, an endogenous estrogen. This structural similarity accounts for the ability of these compounds to bind to estrogen receptors and to exert weak estrogenic or anti-estrogenic effects, depending on the presence of stronger estrogen. It is well known that Secoisolariciresinol has an estrogen-like activity and stimulates the cell growth of human breast cancer MCF-7 cells.