The European Food Safety Authority, (EFSA) who are very tough on foods and supplements, have published a report saying that neither soya nor soy-based food supplements providing isoflavone concentrates pose any risk to post-menopausal women.
EFSA examined all the human data and trials and found no evidence to support the theory that soya-based supplements increased breast cancer, changed mammogram density, nor markers of breast cell proliferation. They saw no evidence of increased endometrial thickness, nor changes to thyroid hormone levels in doses of 150mg per day of isoflavones, taken up to 30 months. They did note minor, non-malignant changes in some cell studies after 60 months the meaning of which is unclear.
I include 80mg of isoflavones in my Female Balance formula, and recommend taking two a day.
Studies have consistently shown lower incidence of breast cancer in both pre and post-menopausal women with higher isoflavones levels as a consequence of eating soya and other beans, including chickpeas.
A recent meta-analysis showed that women with a high soy food intake cut their risk for breast cancer by a third. Another meta-analysis found that ‘that soy isoflavone intake could lower the risk of breast cancer for both pre- and post-menopausal women in Asian countries. However, for women in Western countries, pre- or post-menopausal, there is no evidence to suggest an association between intake of soy isoflavone and breast cancer.’
I think that some of the negative beliefs about soya stem from the existence of GM soya, which I do not recommend at all, and also because soya has been grown on an industrial scale in South America, leading to the destruction of areas of the Amazon. This is lamentable, but not really soya’s fault.
The difference in the positive protective effect between Asian women and largely American women could possibly reflect their widespread use of GM soya.
I only ever eat organic, non-GM soya such as tofu and soya milk, and consider this to be a healthy food.