Phyto Soya is a supplement designed to help women weather the emotional, hormonal and physical changes experienced during menopause. The product is made from soya, or soybean based, isoflavones that work in similar fashion to oestrogen, the female hormone that decreases in the body during menopause. Phyto Soya's manufacturer recommends use of the supplement at the first sign of premenopausal symptoms, during menopause and if you are unable or unwilling to undergo hormone replacement therapy. There are other voices, however, that caution against the dangers associated with soy phytoestrogens.

Phytoestrogens, in some cases, have shown evidence of negatively affecting the endocrine system and its job of coordinating how your body's glands and organs work together. Disruption of endocrine functioning has been studied more in animals than humans but an increasing number of critics are calling for more research to be performed in humans, particularly since there is evidence indicating that endocrine disrupters in women can increase risk of breast and ovarian cancer.

Although soy isoflavones are promoted for their health benefits, their true effectiveness has yet to be backed up with clinical studies. The makers of Phyto Soya proclaim their product's benefits but the jury is still out on whether soy isoflavones are beneficial when used long-term or whether products containing them should be widely used. Ingestion of high levels of isoflavones has been associated with increased occurrence of thyroid disorders, including goitre and Hashimoto's disease.

According to Soy Online Service (SOS), phytoestrogens have the potential to speed the reproduction and growth of cancer cells. SOS claims that post-menopausal women who take soy-based supplements increase their risk of breast cancer. An October 2009 report issued by Cornell University's Program on Breast Cancer and Environmental Risk Factors concluded that studies have been inconclusive and contradictory, therefore, "use of dietary supplements that contain soy phytoestrogens is not recommended."