Hello Althea,
Based on the available research, my opinion is that ground flaxseeds are a healthy and nutritious addition to the diet for women, even if they have a diagnosis or history of breast cancer. I believe this is true regardless of whether a woman has an estrogen receptor positive or estrogen receptor negative cancer type.
The only people for whom I would not recommend flaxseeds are those with digestive conditions such as diverticulitis and ulcerative colitis. In these situations, it is possible that flaxseeds can cause irritation and pain in the digestive tract. However, if these conditions are not an issue, I believe flaxseeds are a great food to include in the diet on a regular basis.
There are many animal and cell studies suggesting that flaxseeds have anti-cancer activities. But as you may know, animal and cell studies don’t give the final answer on what happens in the human body. Fortunately, a very well designed study in 32 women with breast cancer provides further evidence that flaxseeds can provide health benefits and are safe.
This study was quite unique because the researchers managed to collect cancerous breast tissue from a breast biopsy, then have the women eat flaxseeds for 30 to 40 days, then collect cancerous tissue again from the lumpectomy or mastectomy. In this way, they were able to see how the cancer cells looked and “behaved” both before and after the women were eating flaxseeds. While the study was small, it was double-blind and placebo controlled, which is considered the “gold standard” and the best type of study for proving cause and effect.
The researchers were able to keep the study “blinded” by providing the flaxseeds in muffins that were flavored with nutmeg, cinnamon, and vanilla extract so that the women did not know if they were eating muffins that contained ground flaxseed or regular muffins (no flaxseed). The women ate one muffin per day at breakfast.
The results of this study are very encouraging. The researchers found:
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The rate at which the breast cancer tumor cells were dividing and reproducing (cell proliferation) decreased by 34.2% in the women who ate the flaxseed muffins, while there was no change in the proliferation rate of the cancer cells from the tumors of the women who ate the regular muffins (no flaxseed).
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The rate at which the breast cancer tumor cells were dying increased by 30.7% in the women who ate the flaxseed muffins, while there was no change in the rate of cancer cell death in the tumor samples from the women who ate the regular muffins.
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The amount of a protein called c-erbB2 (HER2/neu) that the cancer cells were making decreased by 71.0% in the tissue from the women who ate the flaxseed muffins, while there was no change in the amount of c-erbB2 protein being produced by the cancer cells from the tumors of the women who ate the regular muffins. This is important because cancer cells that produce more of the c-erbB2 protein appear to be more aggressive and may be more difficult to treat.
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Finally, there was no change, in either the flaxseed muffin group or the regular muffin group, in the levels of estrogen and progesterone receptors that the breast cancer cells expressed. Neither the flaxseed muffin nor the regular muffin appeared to have any effect on the estrogen or progesterone receptor status of the breast cancer cells.
As I mentioned, this study only looked at 32 women, which means it was small. But it was very well designed and it provides clear results that eating flaxseeds appeared to give a positive benefit to women with breast cancer, regardless of whether they had estrogen receptor positive or estrogen receptor negative cancers.
Of course I hope that larger, longer term studies on flaxseeds and breast cancer will be conducted to give us even better information about the health benefits of this food. But until that time, I’m comfortable that eating ground flaxseeds is safe and possibly beneficial for women with breast cancer.
In the study I described, the flaxseed muffin contained 25 grams (1 ounce) of ground flaxseed. This is about 3 level tablespoons of ground flaxseed. Other researchers who study the health benefits of flaxseeds suggest that 1 to 3 tablespoons of ground flaxseeds per day is a reasonable goal. Keep in mind that more is not better. There is no reason to eat more than 3 tablespoons per day.
For more information on flaxseeds along with tips and ideas for getting this food into your diet, please see our article “What is Flax?” in the “Your Nutrition Questions Answered” section:
http://www.caring4cancer.com/go/cancer/nutrition/questions/what-is-flax.htm
Nutritionist Suzanne