Soy and Breast Cancer Risk

The University of Ulster reports that eating more soy foods could prevent cancer risk. The use of soy is controversial for a few reasons. 80% of soy in the USA is genetically modified. Many people eat soy as a meat replacement, but it is still highly processed. Processing foods add preservative and food additives that may have their own health risks. Soy is not eaten as a main course in the traditional asian diet. It is most commonly used in it's fermented form.

Therfore eating soy bacon or having even a 4 - 6 ounce soy burger is still not the way soy has been used for centuries. siting the asian diet as evidence for a soy based diet is tricky. This comment by Jeanne Wallace is a favorite resource. We hope it is helpful. It is from our website.

Animals with mammary cancer were fed soy from differing sources—from unprocessed soy foods to highly processed soy protein isolates—all at the same dose level of genistein. While unprocessed soy posed no risk, highly processed soy appeared to promote cancer growth.

With all the focus on the “phytoestrogen” effects of soy, the other beneficial effects of soy against cancer are often overlooked. Soy compounds have been shown to:

• Arrest the cell cycle of cancer cells (induce cytostasis)
• Promote differentiation
• Induce programmed cell death (apoptosis)
• Modify gene expression, down-regulating oncogenes (like Her2neu) and increasing tumor suppressor genes (like p53 and p21)
• Have Anti-angiogenesis actions
• Help inhibit invasion and metastasis

Putting all this together: I favor intake of Tradiational whole soy foods (miso, tempeh, tofu and soymilk), particularly in women who have eaten soy earlier in life and whom are likely to have excess estrogen or significant xenoestrogen exposure. Supplements of high dose soy isoflavones, or processed soy protein isolates, are best avoided.