Ipriflavone, a synthetic isoflavone, has shown some promise in its ability to conserve bone in postmenopausal women. Ipriflavone has also been shown to have a protective effect on bone density in pre-menopausal women taking gonadotropin-releasing hormone (GnRH), a treatment for endometriosis that triggers bone loss.
However, a definitive three-year study of more than 400 postmenopausal women concluded that ipriflavone did not prevent bone loss. Additionally, the compound was linked to lymphocytopenia (a reduction in lymphocytes) in a significant number of study participants. Lymphocytes are a type of white blood cell that helps the body fight infection.
Risks and Benefits Are Unclear
Some studies suggest that, unlike estrogen, phytoestrogens do not appear to target breast or uterine tissue. This suggests that they may act more like SERMS (selective estrogen receptor modulators such as raloxifene and tamoxifen) than actual estrogens. However, in other studies high isoflavone levels have been linked to an increased risk of breast cancer.
Clearly, additional research is needed to further evaluate the effects of phytoestrogens before judgments regarding their safety and usefulness can be made.
Based on information available at this time, it is reasonable to make the following conclusions concerning phytoestrogens and bone health in postmenopausal women:
– Moderate amounts of foods containing phytoestrogens can be safely included in the diet but do not expect it to help build bone. Keep to the basic rule – eat the least processed forms.
– Due to a lack of evidence and concerns about safety, supplementation with synthetic isoflavones (ipriflavone) is in question.
– Postmenopausal women are encouraged to view evidence concerning phytoestrogens and bone health as conflicting and incomplete. For women who are estrogen dominant increasing their phytoestrogen intake may not improve their bone position.