Phytoestrogens Friend or Foe?

Consuming phytoestrogens rich in soy products, nuts, vegetables, coffee and flaxseeds may be protective of certain phenotypes of breast cancer, contrary to previous assumptions. However, timing is critical to reap the benefits of incorporating phytoestrogens into the diet, as phytoestrogen has been found helpful in reducing breast cancer risk when consumed in large amounts during adolescence, especially in preventing breast cancer tumors whose growth is sensitive to estrogen and progesterone receptors.

Elevated estrogen levels have been associated with higher risk of contracting breast cancer. Since phytoestrogens resemble estrogen in the binding of receptors and initiating downstream signaling pathways, phytoestrogen-containing foods such as soybeans, soymilk, tofu and various nuts have been viewed as harmful to eat. However, a group of scientists headed by Dr. Anderson at the University of Toronto has found otherwise in their research. They concluded that eating plenty of phytoestrogens is actually beneficial during adolescence in preventing the on-set of breast cancer.

Breast cancer is a major type of cancer affecting millions of people worldwide. In US alone, one in eight women will develop invasive breast cancer over her lifetime. This recent finding about the beneficial health impacts of consuming phytoestrogens pertains to many women who are looking for ways to prevent breast cancer.

In this study, the researchers recruited 3,101 participants who had been diagnosed with breast cancer and 4,352 control participants. The researchers asked the participants about their frequency of phytoestrogen-rich foods consumption at different periods of their lives and correlated the data with breast cancer frequency.

The researchers found that in adolescents who consumed large amounts of isoflavones (rich in soy products) and lignin (rich in nuts, seeds, cereals, breads, vegetables, coffee and flaxseeds), the risk of contracting breast cancer was significantly reduced in all phenotypes (both estrogen and progesterone receptor sensitive and insensitive). However, the highest total phytoestrogen intake in pre-menopausal women increased breast cancer risk in estrogen and progesterone receptor insensitive tumors. The middle total phytoestrogen intake group in pre-menopausal women, on the other hand, had a lower risk of contracting breast cancer tumors that were estrogen and progesterone receptor insensitive. In post-menopausal women, most of the results were not significant, except for the group high in isoflavone consumption, who had higher risk of contracting estrogen and progesterone insensitive breast cancer tumors.

The discrepancy between differing breast cancer risk among different age group is a telling sign that eating specific foods at specific timesin the life cycle is crucial. Eating foods high in phytoestrogens may be protective of breast cancer, but only if one consumes them during adolescence.

Reference:

• http://www.breastcancer.org/symptoms/understand_bc/statistics
• Anderson et al. Phytoestrogen intake from foods, during adolescence and adulthood, and risk of breast cancer by estrogen and progesterone receptor tumor subgroup among Ontario women. Int. J. Cancer: 132, 1683 – 1692 (2012)