Lignans are phytoestrogens, or plant estrogens. Their precursors are found in a wide variety of plant-based foods and are converted to the lignans, enterodiol and enterolactone, by bacteria in the intestine.
Research suggests these compounds may help protect against hormone-dependent cancers and heart disease.
Because flaxseed is the richest source of lignans, researchers believe it is the synergy of phytonutrients (including lignans) and omega-3's to credit for their beneficial health effects.
Lampe JW. Isoflavonoid and lignan phytoestrogens as dietary biomarkers. J Nutr. 2003;133 Suppl 3:956S-964S.de Kleijn MJ, van der Schouw YT, Wilson PW, Grobbee DE, Jacques PF. Dietary intake of phytoestrogens is associated with a favorable metabolic cardiovascular risk profile in postmenopausal U.S.women: the Framingham study. J Nutr. 2002;132(2):276-282. Valsta LM, Kilkkinen A, Mazur W, et al. Phyto-oestrogen database of foods and average intake in Finland. Br J Nutr. 2003;89 Suppl 1:S31-38.Rowland I, Faughnan M, Hoey L, Wahala K, Williamson G, Cassidy A. Bioavailability of phyto-oestrogens. Br J Nutr. 2003;89 Suppl 1:S45-58.Gordaliza M, Castro MA, del Corral JM, Feliciano ASAntitumor properties of podophyllotoxin and related compounds Curr Pharm Des 2000 Dec;6(18):1811-39, Owen RW, Mier W, Giacosa A, Hull WE, Spiegelhalder B, Bartsch H, Identification of lignans as major components in the phenolic fraction of olive oil. Clin Chem 2000 Jul;46(7):976-88.Wang LQ. Mammalian phytoestrogens: enterodiol and enterolactone. J Chromatogr B Analyt Technol Biomed Life Sci. 2002;777(1-2):289-309. Vanharanta M, Voutilainen S, Nurmi T, et al. Association between low serum enterolactone and increased plasma F2-isoprostanes, a measure of lipid peroxidation. Atherosclerosis. 2002;160(2):465-469.