It’s been nearly 20 years since the first research suggested a link between early soyfood consumption and a reduced risk for breast cancer. Researchers believe that consuming soy isoflavones during puberty can affect breast cell development in a way that provides protection against cancer. Since then, several studies have confirmed this relationship in Asian women but there have been fewer findings among non-Asians.
New research from Canada suggests that soy may be protective in Caucasian women as well. Women with and without breast cancer filled out a food frequency questionnaire designed to assess isoflavone intake within the past two years and also during puberty and early adolescence. In this study, adult intake of soyfoods wasn’t associated with risk for breast cancer. However, women who consumed the most soy isoflavones during their teenage years were about 20% less like to have cancer later on in life.
Isoflavones were protective primarily against estrogen-sensitive breast cancer, that is, breast cancer whose growth is stimulated by estrogen. More importantly, the women in this study consumed very little soy during adolescence since soyfoods were not commonly consumed at that time. This raises questions about whether such low intakes of soy isoflavones could possibly be protective. But while further research is needed to confirm the findings, they add to the growing body of data suggesting a protective role for soyfoods in the diets of young girls.
Anderson LN, Cotterchio M, Boucher BA, Kreiger N. Phytoestrogen intake from foods, during adolescence and adulthood, and risk of breast cancer by estrogen and progesterone receptor (ERPR) tumour subgroup among Ontario women. Int J Cancer 2012.