Do Soy Foods Cause or Prevent Breast Cancer? Part I

This question regarding soy foods and breast cancer is one that I get often when talking with groups or individuals. Although numerous studies claim positive effects of soy foods on cancer
risk, other studies have found no effects, or unwanted effects.

It was just last week I spoke to a breast cancer survivor who was told by her oncologist to avoid soy foods. She described to me her difficulty as she was avoiding all products with any form of soy, including soybean oil!

Phytoestrogens in Soy

When health professionals talk about soy foods in relation to breast, ovarian or endometrial cancer, it is the phytoestrogens in the soy that we are talking about. Phytoestrogen refers to the phytochemicals in soy that appear similar to human estrogen in chemical structure.

In this survivor’s case, she was avoiding all forms of soy. However, the active phytoestrogens that are in question are mostly concentrated in the highly processed soy supplements, such as soy protein isolate, isoflavone-rich soy extracts, or isoflavone capsules and not in soybean oil or “natural” versions of soy, like tofu, soymilk or soybeans.

In questions like this where research has not provided a clear conclusion, it is important to evaluate 3 things. First, understand the facts and what we know for sure. Second, understand the current theories. Third, you get to decide what is best for YOU!

In Part I we will cover the first of these three. The final two things will be discussed in Part II.

1. Understand the Facts.

First off, it is important to know that there are many more significant factors that can increase risk of breast cancer than eating soy foods. The most significant risk factors for breast cancer when it comes to lifestyle include:

• being overweight or obese
• taking hormones after menopause
• smoking
• excessive alcohol intake

In part II of “Do Soy Foods Cause or Prevent Breast Cancer?”, we will discuss current theories and recommendations and guide you in making your personal choice.

If you want more information before Part II comes out, be sure to review these two posts I wrote earlier this year:

Soy Foods and Cancer
Soy Foods and Cancer – RECIPE!

– Julie