Numerous health benefits have been linked to phyto-oestrogens including preventative and therapeutic effects against carcinogenesis, osteoporosis and atherosclerosis as well as other benefits (Patisaul and Jefferson, 2011). However many have also been found to cause detrimental effects such as disturbance of lactation, the timing of puberty, compromised fertility as well as paradoxically increasing the risks of what they are meant to prevent/treat etc. as mentioned by Patisaul and Jefferson (2011).
Phyto-oestrogens are a class of plant-derived polyphenols that have a very similar binding site chemical structure to 17β-oestradiol, the oestrogen hormone found in mammals, according to Limer (2004).
They therefore also exhibit oestrogenicity as their binding sites can interact with mammalian oestrogen receptors (ER-α, ER-β and GPR30). We shall focus on their effect on the major ERs (ER-α, ER-β) in this article. Mammalian oestrogen binds to ER- α and ER-β with equal affinity unlike phyto-oestrogens which most are more selective for ER- β (Anklesaria, 2011). Their selective nature to particular oestrogen receptor targets classifies phyto-oestrogens as a type of natural selective oestrogen receptor modulator (SERM) (Anklesaria, 2011) and a dietary oestrogen as most are synthesised by plants and found in a vast array of foods (Kuhnle et al., 2008)
There are a number of groups of phyto-oestrogens but the major classes are: isoflavones (genistein, daidzein, biochanin A), lignans (enterolactone and enterodiol), coumestans (coumestrol) and the stilbenes (resveratrol) ( Limer and Speirs (2004).
A study conducted by  Kuhnle et al. (2008) which was the first study to measure individual concentrations of phyto-oestrogens in food that had originated from animals and meat substitutes found phyto-oestrogens were present in all of the food analysed and at a dramatically higher concentration in soy products e.g. In a generic infant soy formula a concentration of 19 221 μg/100 g of phyto-oestrogens was found in comparison to a concentration of 59 μg/100 g in non-soy infant formula. In the study by Kuhnle et al. (2008) the dramatically higher concentrations of phyto-oestrogen in soy products were primarily attributed to an extremely high level of isoflavone phyto-oestrogen class.
Phyto-oestrogens are getting a lot of attention for their health benefits especially isoflavones as soy-products are the most commonly eaten phyto-oestrogen containing food and as further proof amounts for their role in relieving and decreasing vasomotor symptoms during menopause and managing bone health especially important for post-menopause (Pitkin, 2012).
The effect of phyto-oestrogens has also been sometimes described as negative. The effect of phyto-oestrogens on infertility was first noticed in the 1940s in Australia when sheep grazing on pasture composed of clover of the Trifolium species developed large scale infertility (Sunita and Pattanayak,...