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Food
sources of phyto-oestrogens and their precursors in Europe.
Br J Nutr. 2003 Jun;89 Suppl 1:S39-43.
Fletcher RJ.
Kellogg Company, Manchester, UK. reg.fletcher@kellogg.com
Phyto-oestrogens are dietary components found in some plants, which act in vivo
like weak oestrogens. They may reduce the risk of some degenerative diseases
moderated by oestrogen, including breast cancer and osteoporosis. The most
widely studied are the isoflavones genistein and daidzein from soyabeans, but
lignans may be more prevalent in the European diet. Soya foods have
traditionally been consumed in the Orient for millennia, and are now widely
available to European consumers. Levels of isoflavone in soyabeans from
published literature vary between 560 and 3810 mg/kg, depending on variety and
growing conditions. Soya protein concentrates and isolates derived from
soyabeans contain 466-615 mg isoflavones/kg. Traditional soya milk, bean curds,
bean sprouts, etc. contain 13 to 2030 mg isoflavone/kg, depending on the
starting raw material and final water content. Fermented foods have a different
isoflavone conjugate profile, which may be important in absorption and
metabolism. Soya analogues of European foods include dairy and meat products,
which contain 38 to 3000 mg total isoflavones/kg, depending the source of soya
and dilution with other ingredients. A wide range of foods contain low levels of
soya-derived isoflavones, but such foods do not make a significant contribution
to mean intakes in Europe. Flaxseed is by far the richest source of lignan
precursors. However, foods such as cereal brans, legumes and some vegetables are
a more important source in the diets of Europeans because they are more widely
consumed. For similar reasons, compared with soya isoflavones, lignans may be a
more important source of phyto-oestrogens in the diets of Europeans.
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