Development and application of screening assays for the beneficial and adverse effects of phytoestrogens in food

Previous methods developed to detect phytoestrogens in food samples can only identify known compounds, and may not detect phytoestrogens at very low concentrations. Therefore, more versatile and sensitive methods to detect phytoestrogens in food are required.

This project aims to develop biological methods to screen for the presence of compounds in plant-based foods which have oestrogenic (can mimic oestrogen) or anti-oestrogenic (block the action of oestrogen) properties. The methods developed will be validated against chemical analytical methods and bioassays. A range of food extracts will be analysed for the presence of phytoestrogens using the methods developed.

Two biological systems to measure the potency of oestrogenic compounds were developed. The first system was enzyme-based, whereas the second involved the use of yeast cells.

Analysis of purified phytoestrogens using the systems showed that phytoestrogens present in soya were 2000-8000 times less potent than the natural human oestrogen, oestradiol. Some phytoestrogens found in hops were more oestrogenic, whereas compounds from onions and citrus fruits were inactive.

Analysis of a range of food extracts showed that they were oestrogenic in the following order; a phytoestrogen-containing dietary supplement > soya flour > Burgen bread > soya-based infant milk formula >> white bread (containing soya flour) > cows milk infant formula. The oestrogenic activity of the extracts was found to correlate with the concentrations of phytoestrogens in the samples, which were measured using a chemical analytical method. Some of the phytoestrogens isolated from these extracts were also found to be weakly oestrogenic using a separate bioassay.

The biological systems could be used in conjunction with chemical analytical methods to allow improved detection and quantification of phytoestrogens in a wide range of foods.

The results of this project were evaluated by the Committee on Toxicity (COT) as part of its review on phytoestrogens and health.

Final report is available from the FSA Library and Information centre.
To obtain a copy, please contact the Enquiry Desk, Dr Elsie Widdowson Library and Information Services, Food Standards Agency tel: 020 7276 8181/8182 or email: library&info@foodstandards.gsi.gov.uk).

Publications

Coldham, N.G. et al (2002). A binary screening assay for pro-oestrogens in food: metabolic activation using hepatic microsomes and detection with oestrogen sensitive recombinant yeast cells. Food Addit Contam 19,1138-47.

Coldham, N.G. et al (2001). Identification, quantitation and biological activity of phytoestrogens in a dietary supplement for breast enhancement. Food and Chemical Toxicology 39, 1211-1224.

Presentations

Coldham, N.G. (2000). Analysis of phytoestrogens in food by LC-MS. British Mass Spectrometry Society Food Analysis Group meeting at Unliver, Sharnbrook.

Coldham, N.G. (1999). Development of screening assays for phytoestrogens in food. Society for Chemistry in Industry workshop.