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SECOND INTERNATIONAL SYMPOSIUM
ON THE ROLE OF SOY
IN PREVENTING AND TREATING CHRONIC DISEASESeptember 15-18, 1996
Brussells, Belgium
POSTER ABSTRACTSThe Determination of Isoflavonoids and Lignans in Human Breast Milk from British and Chinese Women by Gas Chromatography-Mass Spectrometry.
Morton MS1, Leung SSF2, Davies DP3, Griffiths K1 and Evans BAJ3.
1. Tenovus Cancer Research Centre, Cardiff, UK.
2. Prince of Wales Hospital, Shatin, Hong Kong.
3. Department of Child Health, University of Wales College of Medicine, Cardiff, UK.
There is increasing interest in the possible beneficial or adverse effects of phyto-oestrogens on health. We have carried out a pilot study to assess Gas Chromatography-Mass Spectrometry (GC-MS) as a method for the determination of phyto-oestrogens in human milk and to compare the levels of these compounds in milk from British and Chinese women. In this isotope dilution GC-MS method an internal standard cocktail containing deuterated analogues of the lignans, enterolactone and enterodiol, and the isoflavonoids, equol, daidzein and genistein, was added to a well mixed aliquot (5ml) of breast milk. After equilibration, conjugates present were hydrolysed by overnight incubation with a mixed aryl sulphatase/SYMBOL 98 \f "GreekMathSymbols"-glucuronidase (Helix pomatia) in acetate buffer at 370C. The aglycones were extracted with diethyl ether and the dried extract chromatographed on Sephadex LH20 columns which were washed with chloroform/heptane/methanol (10:10:1). The phyto-oestrogens were eluted with methanol, the eluate dried and derivatised for GC-MS by forming the trimethylsilyl ethers. Isotope dilution GC-MS with Selected Ion Monitoring was carried out using a Finnigan Masslab MD800 benchtop quadrupole mass spectrometer coupled to a GC8000 gas chromatograph.
The levels of phyto-oestrogens in milk obtained from three British (Cardiff) and five Chinese (Hong Kong) women were measured. Although low levels of enterolactone (1.3-1.4ng/ml) were observed in two of the samples from Cardiff, equol and enterodiol were not detected. Daidzein (10ng/ml) and genistein (3.3ng/ml) were found in only one of these British samples. In the five milks obtained from Hong Kong, equol (0.26 and 2.8ng/ml) was observed in two, enterolactone (0.15-1.9ng/ml) and daidzein (0.74-8.6, mean 3.6ng/ml) in three and genistein (0.8-12.6, mean 4.8ng/ml) in four.
As far as we are aware this is the first time that phyto-oestrogens have been reported in human milk. The levels found in this preliminary study were low when compared to the levels observed (daidzein 13,740ng/ml, genistein 8,690ng/ml) in the one soya milk formula analysed.
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