Phytoestrogens and health

Moizer, T. Barlow, B. Jeffery and S. Paul, Food Standards Agency, UK 

Soy-based infant formula contains relatively high concentrations of phytoestrogens. As such, formula fed infants may be exposed to higher concentrations than the average consumer. Mean intakes of phytoestrogens in the UK have been estimated to be 4.5-5 mg/kg bw/day (MAFF, 1998), although other studies have indicated that consumption could potentially be 

2 Mechanisms of phytoestrogen action receptor and non-receptor mediated 

Phytoestrogens may elicit their biological effects by binding to estrogen receptors (ERs). Until recently, only a single ER isoform, ERa, had been identified however, a second receptor termed ERp has also been identified (Enmark et al, 1997, 1999 Saunders et al, 2000, 2001). It has been shown that the ERs have different intracellular and tissue distribution patterns and are responsible for different biological effects (see Table 5.1). A number of spliced variants of both ERa and ERp have also been identified (Inoue et al, 2000 Ogawa et al, 1998 Vladusic et al, 1998). 

In addition to direct interaction with ERs, phytoestrogens may also act indirectly to modulate the concentration of endogenous estrogens. 

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Cornwell T, Cohick W, Raskin I. Dietary phytoestrogens and health. Phytochemistry 65, 995-1016, 2004. 

King R. 2002. Digestion, absorption, and metabolism of isoflavones. In Gilani G, Ed. Phytoestrogens and Health. Illinois AOCS Press, PP. 209-234. 

Hasler, C.M. Kundrat, S. Soy isoflavones as functional ingredients in women s health. In Phytoestrogens and Health 2002 32-50. 

Cornwell, T., W. Cohick, and 1. Raskin. 2004. Dietary phytoestrogens and health. 

The mucosa of the GIT represents an interface between the external and internal environments. The expansive surface area is necessary for the efficient hydrolysis of foodstuffs and the absorption of energy and nutrients. The mucosa also influences the systemic availability of non-nutrient compounds in the diet, both beneficial and detrimental. Digestion and absorption of glucosinolates are critical determinants of health benefits (see Chapter 4) Similarly, the bioavailability and health benefits of phytoestrogens, such as genistein (see Chapters 5 and 10) are at least partly dependent on the carrier-mediated processes of absorption associated with the GIT (Oitate et al, 2001). Moreover, the metabolic activities of the mucosa can influence the systemic concentrations and forms of dietary phytochemicals, as exemplified by research with soy isoflavones (Andlauer et al., 2000). 

In order to get recent advances on the effects of phytoestrogens on hormonal-dependent diseases as well as on human supplementation trials, it might be useful to refer to http //www.venus-ca.org/ (EU-funded project on dietary exposure to phytoestrogens and related compounds and effects on skeletal tissues) http //www.phytos.org (EU-funded project on the prevention of osteoporosis by nutritional phytoestrogens) http //www.phytoprevent.org (EU-funded project on the role of phytoestrogens in the prevention of breast and prostate cancer) and http //www.nutrition.tum.de/isoheart.htm (EU-funded project on cardiovascular health of postmenopausal women). 

Swinny, E.E. and Markham, K.R., Applications of flavonoid analysis and identification techniques isoflavones (phytoestrogens) and 3-deoxyanthocyanins, Flavonoids in Health and Disease, 2th edn, Rice-Evans, C.A. and Packer, L., Eds., Dekker/CRC Press, London, 2003, 97. 

Lissin LW, Cooke JP. 2000. Phytoestrogens and cardiovascular health. J Am Coll... 

Davis SR, Dalais FS, Simpson ER and Murkies AL (1999) Phytoestrogens in health and disease. Rec Prog Hormone Res 54, 185-210. 

Hughes, C.L. (1988). Phytochemical mimicry of reproductive hormones and modulation of herbivore fertility by phytoestrogens. Environ. Health Perspectives, 78, 171-174. 

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