Cambridge Journals Online

Symposium on ‘Phytochemicals’

Critical review of health effects of soyabean phyto-oestrogens in post-menopausal women

Aedin Cassidya1 c1, Paola Albertazzia2, Inge Lise Nielsena3, Wendy Halla4, Gary Williamsona3, Inge Tetensa5, Steve Atkinsa2, Heide Crossa6, Yannis Maniosa7, Alicja Wolka8, Claudia Steinera9 and Francesco Brancaa10 a1 School of Medicine, Health Policy and Practice, University of East Anglia, Norwich NR4 7TJ, UK a2 Centre for Metabolic Bone Disease, Hull Royal Infirmary, Hull HU3 2RW, UK a3 Nestlé Research Center, Vers Chez Les Blanc, Lausanne, Switzerland a4 School of Food Biosciences, University of Reading, Reading RG6 6AP, UK a5 Department of Nutrition, Institute for Food and Agricultural Research, Søborg, Denmark a6 Department of Pathophysiology, Medical University of Vienna, Vienna, Austria a7 Department of Nutrition and Dietetics, Harokopio University, Kallithea-Athens, Greece a8 The National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden a9 Institute of Nutrition, Friedrich-Schiller University of Jena, Jena, Germany a10 National Institute for Research and Food and Nutrition (INRAS), via Ardeatria 546, 00178 Roma, Italy

Article author query cassidy a   albertazzi p   nielsen il   hall w   williamson g   tetens i   atkins s   cross h   manios y   wolk a   steiner c   branca f

Abstract

A consensus view of soyabean phyto-oestrogens in clinical interventions in post-menopausal women is presented that is based on data from the EU-funded project Phytohealth. The phyto-oestrogens, primarily genistein and daidzein, were given as soyabean-protein isolates, whole-soyabean foods or extracts, supplements or pure compounds. A comprehensive literature search was conducted with well-defined inclusion or exclusion criteria. For areas for which substantial research exists only placebo-controlled double-blind randomised controlled trials (RCT) conducted on healthy post-menopausal women were included. For emerging areas all available human studies in post-menopausal women were reviewed. In order to make cross comparisons between studies the doses of isoflavones were calculated as aglycone equivalents. There is a suggestion, but no conclusive evidence, that isoflavones from the sources studied so far have a beneficial effect on bone health. The consumption of whole-soyabean foods and soyabean-protein isolates has some beneficial effects on lipid markers of cardiovascular risk. The consumption of isolated isoflavones does not affect blood lipid levels or blood pressure, although it may improve endothelial function. For menopausal symptoms there is currently limited evidence that soyabean-protein isolates, soyabean foods or red-clover (Trifolium pratense L.) extract are effective but soyabean isoflavone extracts may be effective in reducing hot flushes. There are too few RCT studies to reach conclusions on the effects of isoflavones on breast cancer, colon cancer, diabetes or cognitive function. The health benefits of soyabean phyto-oestrogens in healthy post-menopausal women are subtle and even some well-designed studies do not show protective effects. Future studies should focus on high-risk post-menopausal women, especially in the areas of diabetes, CVD, breast cancer and bone health.

Key Words: Genistein; Daidzein; Bioavailability; Bone health; CVD

Correspondence:

^c1 *Corresponding author: Professor Aedin Cassidy, fax +44 1603 593752, email a.cassidy@uea.ac.uk