Phytoestrogen's Role in Estrogen-Positive Breast Cancer Patients

Ask the Nutritionist

Q: You touch on the topic in your archives, but I am still unclear whether or not phytoestrogens are a "good thing" or a "bad thing" for we estrogen positive breast cancer patients. I am clear on the concentrated soy products and supplements being potentially problematic, but how about all the other fruits and vegetables with phytoestrogens? Can they be harmful, in spite of being part of a "healthy" plant-based diet? Additionally, I have read (elsewhere) that the phytoestrogens in flaxseeds can actually attach to estrogen receptors and block or protect the receptors from the evil-doer estrogens and prevent them from contributing to the growth of an ER+ tumor. Is that true, or just another unproven philosophy out there to further confuse us? And to clarify, is flaxseed oil safer for us than the flaxseeds, even as ground flaxseeds? Thank you!!

Holly, New Castle, New Hampshire, October 2015

A: The issue of phytoestrogens is very confusing for all cancer survivors.

Your knowledge of soy products matches our recommendations.

Research on lignans found in flaxseeds is ongoing. According to the American Institute for Cancer Research, current research suggests that flaxseed may be protective, especially in post-menopausal women, and consuming flaxseed does not increase risk for breast cancer. Previously, it was thought that the lignans, which are phytoestrogens, would act like estrogen in the body. However, current research indicates that is not the case.

Flaxseed also provides other nutrients, including dietary fiber and omega-3 fats, which are both an important part of a healthy diet. Typically, up to 1-2 tablespoons per day of ground flax seed is suggested.

You may consume pure flaxseed oil if you choose. The oil is stripped of the woody shell, and is not a source of fiber, but is still a good source of alpha linoleic acid (ALA), an omega-3 fat, which may have cholesterol-lowering properties. Since flaxseed oil is a dense source of calories we suggest limiting amounts to 1-2 tablespoons per day.

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