Lignin is not a polysaccharide but is chemically bound to hemicelluloses in plant cell walls. It has been suggested that lignins are precursors to mammalian lignans, such as enterolactone and enterodiol (Begum et al., 2004). Lignins are found in all vessels and secondary tissues of higher plant species and therefore are present in a variety of foods, such as celery and the outer layers of cereal grains. Unlike lignans, which are present in plant vacuoles and tend to be specific to a limited number of plant species. Plant lignans are metabolised by the colonic microflora to form mammalian lignans. Mammalian lignans can bind weakly to the oestrogen receptor exerting both oestrogenic and antioestrogenic effects (Wang, 2002).
Mammalian lignans have been linked to a number of possible health benefits. This includes helping to reduce the risk of CHD, protecting against osteoporosis and playing a role in the management of menopausal symptoms (Cassidy, 2003; Rowland et al., 2003; Wang, 2002). It has also been suggested that mammalian lignans possess antioxidant capabilities.
High levels of enterolactone and enterodiol in human plasma and urine are associated with diets rich in fibre, wholegrain cereals, fruits and vegetables. Therefore, it was suggested that lignin, which is found in all higher plant species, is a precursor to mammalian lignans.
References
Cassidy, A. (2003). Dietary phytoestrogens and bone health. British Menopause Society Journal, 9 (1), pp. 17-21.
Rowland, I., Faughnan, M., Hoey, L., Wähälä, K., Williamson, G., & Cassidy, A. (2003). Bioavailability of phyto-oestrogens. British journal of nutrition, 89(S1), S45-S58.
Wang, L. Q. (2002). Mammalian phytoestrogens: enterodiol and enterolactone. Journal of Chromatography B, 777(1-2), pp. 289-309 (Article).
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