From The Times this week, nutritionist Amanda Ursell tackles some knotty questions about soy foods.
I’ve read that soya milk increases the risk of breast cancer. Should I avoid it?
Soya milk and soya products, such as yoghurts, tofu and tempeh soyabean cake, contain plant chemicals known as isoflavones. These “super nutrients” are said to have “oestrogen-like” effects in our bodies. Given that the risk of breast cancer has been linked to a higher level of oestrogen, it is logical to assume that soya may increase the danger.
However, studies in humans have found no effect from soya isoflavones on either breast tissue density or breast cell proliferation, both of which are markers for increased breast cancer risk.
Among women who have had breast cancer, the Shanghai Breast Cancer Survival Study, which included 5,000 women six months after diagnosis, showed that those who ate about 15g of soya protein a day had a 33 per cent lower risk of dying from breast cancer or relapsing compared with women who ate the least soya protein (6.6g per day).
Given that research on both pre and post-menopausal women who ate significant amounts of soya-based foods has found no significant effect on oestrogen levels in the body, it is likely that whatever good things soya does for our general health, it is independent of hormone levels.
Read the rest of the Q&A at The Times Online