I regularly get calls from women who have had breast cancer and who have been instructed by their physician to avoid all soy products due to their estrogenic effects.

Soy contains phytoestrogens, the doctors say, and for women who have estrogen positive breast cancer, they are at increased risk if they consume it.

First, there are 3 classes of phytoestrogens – isoflavones are found in soybeans and garbanzo beans.  Lignans are found in flax seeds and whole grain cereals.  And coumestans are found in clover, alfalfa and soybean sprouts.  While women are told to avoid soy, they are not instructed to avoid other phytoestrogen-containing foods like the ones listed above.

Asian populations consistently consume soy foods, yet have significantly lower rates of breast cancer than Americans do.  A study published last year in the Journal of the National Cancer Institute examined soy as an isolated factor in Japanese women and (Yamamoto et al, 2003;95:906-913) concluded that frequent soy consumption was associated with a reduced risk of breast cancer.

It is true that women with estrogen positive breast cancers, and in fact, all women, should be concerned with estrogen levels.  However, the way to lower estrogen levels is:
•    Consume a high fiber diet – fiber helps the body to eliminate excess estrogen.  In the absence of enough fiber, estrogen will be re-absorbed through the intestinal walls back into the blood stream, contributing to elevated estrogen levels.
•    Exercise – absolutely lowers estrogen levels
•    Reduce body fat, which is a virtual estrogen manufacturing facility

I receive frequent calls from women who are over-fat, eat a terrible diet, and do not exercise, and who are wondering what to do about the soy issue.  Removing soy from the diet and not addressing these other factors is like rearranging the deck chairs on the Titanic.  In order to protect against a recurrence of breast cancer, ideal weight and body composition must be attained and a proper diet and exercise are crucial.  In that context, soy generally offers a protective rather than detrimental effect.