Phyto-oestrogens are bioactive substances found in plant foods, with naturally occurring oestrogenic activity. Soy beans and other foods containing soy, such as tofu, tempeh and soy milk, are rich sources of phyto-oestrogens.
There is limited suggestive evidence that soy foods may lower the risk of prostate and stomach cancer. Current evidence is too limited to permit a probable or convincing causal judgement, but does suggest there is an effect. The evidence for soy foods and cancer of the pharynx, oesophagus, pancreas, breast and endometrium is limited such that no conclusion can be made of an association. There is no association between soy foods and the risk of other cancers, including bowel cancer.
While soy foods may have a protective effect, there is also some evidence that phyto-oestrogens might stimulate the growth of existing hormone-dependent cancers.
Cancer Council supports the consumption of soy foods in the diet. This is consistent with Cancer Council recommendations and national dietary guidelines to eat a diet high in plant based foods.
Cancer Council does not recommend or support the use of supplements such as soy protein isolates or isoflavone capsules for healthy men and women to prevent cancer.
See the full position statement:
Soy, Phyto-oestrogens and Cancer Position Statement