EU-funded projects to explore the physiological effects from eating foods with added soy-derived isoflavones are hoping to see benefits for bone health and heart disease reduction in women.
The Isoheart project is aiming to establish the presumed health benefits of phytoestrogens, on reducing the risk of heart disease in postmenopausal women. Scientists will also study the consumer acceptability of foods enriched with isoflavones.
Research already shows that isoflavones from soya, chickpeas and other legumes may protect older women from heart diseases.
Before the menopause, the hormone oestrogen is believed to protect women from the common risk factors for heart disease, such as high blood pressure and high blood cholesterol levels. After the menopause and the corresponding fall in oestrogen levels, the protective effect diminishes and death rate from heart disease increases in women.
Animal studies and preliminary human studies have shown phytoestrogens, compounds similar to oestrogen occurring naturally in certain plants, may reduce risk of heart disease. However, little is known about how these compounds actually affect the cells in blood vessel walls.
Another recently completed European project, Venus, aiming to assess the effect of phytoestrogens on bone health, concludes that although they have modest positive effects on the development of osteoporosis in experimental animals, more well-designed human studies are needed before making general recommendations.
Based on a database on phytoestrogens (PEs) within European diets compiled by the Venus team, led by Prof Francesco Branca at the Istituto Nazionale di Ricerca per gli Alimenti e la Nutrizione (INRAN) in Rome, Italy, PE intake in Europe is estimated to be less than 1 mg/day, compared to an intake of 20-100 mg/day in Asia and to the expected range for physiological effect, 60-100 mg/day.
Bioavailability studies confirmed that most PEs are readily absorbed by humans, but large subject variability was found, possibly due to variability in gut microflora, diet and metabolism, suggest the researchers.
They add that because isoflavones are mostly found in soy products, which are not extensively used in Europe, an adequate intake in European diets may be difficult. For this reason, the team worked out a number of menus containing soy fractions which would significantly contribute to an increased PE intake. PEs considered for the Venus study included isoflavones (genistein and daidzein), coumestrol, formononetin, biochanin A, and lignans.
Missing links identified by the Venus project will be taken up by the recently launched European project called Phytos. The major objective of the new project is to provide clear scientific evidence about the effects of soy isoflavones on markers of osteoporosis in postmenopausal women.
The Isoheart project is being run by Professor Susanne Bügel at the Department of Human Nutrition in the The Royal Veterinary and Agricultural University, Frederiksberg, Denmark. Further updates on the project will be published in future news.