Flax seeds are a “Phytoestrogen” which can raise or lower the risk of developing breast, ovarian, and uterine cancers, since these types of cancers are typically estrogen-driven. Overall results of these studies have been inconclusive. Some research found a decrease in risk with higher phytoestrogen intake, while other research suggests that for certain people, the risks of consuming these “fake” estrogens may outweigh the benefits. As a health coach I highly suggest women stay clear of flax, especially when it is in the ground up form. Read for yourself
Who Should Avoid Flaxseeds?
If you or your loved one has a history of any of the following conditions, then substitute fish oil in place of flax to get your daily dosage of healthy omega-3 fatty acids.
Women who have a history of breast, ovarian, or uterine cancer, especially estrogen-receptive breast cancer. In addition to their ability to mimic estrogen, phytoestrogens have been shown to cause growth of breast tissue in animals and healthy women, so they are not recommended for breast cancer survivors.
Women who have a BRCA1 or BRCA2 gene defect. Women with one of these defects have up to an 80 percent chance of getting breast cancer sometime during their life; therefore, these women should avoid phytoestrogens including flaxseeds and soy.
Women with a history of endometriosis or polycystic ovarian syndrome. Again, these are hormonal-driven conditions, so phytoestrogens are not recommended.
Women who are taking birth control pills or any type of hormone replacement therapy. Both birth control pills and HRT contain estrogen, so phytoestrogens might disrupt or amplify the effect of the estrogen.
Women who are pregnant or breastfeeding. Pregnant or breastfeeding women should not consume substantial amounts of flaxseeds on a regular basis. In fact, in animal studies, the phytoestrogens in flaxseeds have been shown to cause developmental abnormalities and have been linked to an increase in susceptibility of cancer in offspring.
Infants and young children. Phytoestrogens are not recommended for young children; use fish oil in place of flax. Adolescent girls and young women under 30. Adolescent girls and young women under 30 can consume flax on a limited basis (one to two times per week), but should not have flax daily.
Who Should Take Flaxseeds?
It is important to remember that the healthy omega-3 fat from flaxseeds is alpha linolenic acid (or ALA), a type of omega-3 that must be converted by the body to the highly beneficial fatty acids (EPA and DHA) found in salmon and other fatty cold-water fish.
Because the ALA conversion to EPA and (especially) DHA is very poor in most people, it is best not to rely solely on flax for your total omega-3 intake.
Flaxseed consumption can be healthy, particularly for:
Men who have a history of prostate disease, including prostate cancer. A study performed by researchers at the University of Texas M.D. Anderson Cancer Center found that men with prostate cancer who ate 3 tablespoons of milled or ground flaxseeds each day had decreased prostate cancer cell proliferation compared to similar men who did not eat flaxseeds. According to the American Cancer Society, men who supplement their diets with flaxseed have lower PSA levels and slower growth of benign as well as cancerous prostate cells.
Postmenopausal women or women who are estrogen-deficient. Postmenopausal women (with no personal or familial history of hormonal cancers) can benefit from flaxseed consumption, particularly to help with menopausal symptoms and preventing or reversing osteoporosis.
Flaxseeds have been shown to help control blood sugar levels, decrease LDL cholesterol, and promote weight loss. “Flaxseed Supplementation (Not Dietary Fat Restriction) Reduces Prostate Cancer Proliferation Rates in Men Presurgery.” Cancer, Epidemiology, Biomarkers & Prevention. December 2008 17; 3577.  Cornell Univeristy.  American Cancer Society.  Duffy, Christine, et. al., “Implications of Phytoestrogen Intake for Breast Cancer,” CA: A Cancer Journal for Clinicians, September 2007 (57:260-77).