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 

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

Your knowledge of soy products matches our recommendations.

The reputation of flaxseed as a cancer promoter or preventer is still being debated. It is an excellent source of omega-3 fatty acids, but the seed (not the oil) is an antioxidant with possible estrogen receptor activity.

There is not enough evidence to recommend whether people should stop eating flaxseeds or eat more of them.

Because the research on flaxseed's effect on estrogen is inconclusive, we recommend that patients with estrogen-receptor positive breast cancer consume ground flaxseed in moderation – one tablespoon per day as an upper limit.

You may consume pure flaxseed oil if you choose. The oil is stripped of the woody shell, but is still a good source of alpha linoleic acid (ALA), which may have cholesterol-lowering properties.

You do not have to limit your consumption of the oil to one tablespoon, as long as it fits within your healthy eating plan. Flaxseed oil, like all oils, is dense in calories.

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