Although the health benefits of flaxseed have been touted for years, not everyone is so quick to jump on the flaxseed bandwagon. Some skeptics warn that because this tiny seed that comes from the flax plant contains plant estrogens, it may actually promote estrogen-sensitive cancers.
But before deciding whether to eat or avoid flaxseed, learn what the studies have to say about lignans, the plant estrogens or phytoestrogens found in whole and ground flaxseed, and their health benefits. Who knows? Flaxseed may just become a regular habit.
Flax Lignans and Breast Cancer
While it’s true that flaxseed contains phytoestrogens, not all phytoestrogens are the same. There are two major types of phytoestrogens: isoflavones and lignans. Lignans are the phytoestrogens found in the fiber portion of flaxseed.
Even though research regarding phytoestrogens and breast cancer has had mixed results, most studies suggest that lignans play a protective role in the disease. How? By mimicking the effects of the hormone estrogen. Lignans compete with a woman’s endogenous estrogen and bind to estrogen receptors in the body, thereby blocking the stronger, cancer-stimulating estrogen.
Even women who have already had breast cancer and are taking tamoxifen can benefit from flax’s lignans, according to a report in the September 2007 issue of CA: A Cancer Journal for Clinicians, since lignans don’t interfere with tamoxifen’s anti-cancer actions in the way that isoflavones might. What's more, in a recent study, scientists at the German Cancer Research Center found that lignans lower the risk of secondary tumors, metastasis, and breast cancer deaths in postmenopausal women with ER-negative tumors (tumors that have no receptor for the estrogen hormone) by up to 40 percent.
Flax Lignans and Prostate Cancer
When it comes to prostate cancer, there’s more good news about flax lignans. A 2008 study performed by researchers at the University of Texas M.D. Anderson Cancer Center found that men with prostate cancer who ate three tablespoons of milled or ground flaxseed each day had decreased prostate cancer cell proliferation compared to similar men who did not eat flaxseed.
According to the American Cancer Society, other studies have shown that men who supplemented their diets with flaxseed had lower PSA levels and slower growth of benign as well as cancerous prostate cells.
Other Health Benefits of Flax Lignans
Because of the powerful antioxidant and anti-inflammatory properties of lignans, they also help protect the heart. A 2009 study by Dr. Kailash Prasad at the University of Saskatchewan in Canada found that the main lignan in flaxseed, secoisolariciresinol diglycoside (SDG), was responsible for slowing the progression of plaques and decreasing oxidative stress that harms the lining of blood vessels.
SDG has also been associated with a reduction in type 1 and type 2 diabetes and has been proven to lower blood glucose levels and cholesterol levels, especially in postmenopausal women.
The verdict on flax? Research has shown that its lignans carry powerful health benefits that aid in disease prevention and reduction, making flaxseed worth consuming regularly. Experts recommend anywhere from one to three tablespoons of flaxseed per day for a safe, effective dosage. For optimal results, choose fresh ground flaxseed, since flaxseed oil and supplements don’t always contain lignans.
For more information on flaxseed, see:
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
Sources:
"A Flax Lignan Complex Slows the Progression of Atherosclerosis in Hypercholesteroemic Rabbits," Dietitians' News, Flax Council of Canada, 2009.
American Cancer Society.
Ameriflax.
Denmark-Wahnefried, Wendy, et. al., “Flaxseed Supplementation (Not Dietary Fat Restriction) Decreases Prostate Cancer Proliferation Rates in Men Presurgery,” Cancer Epidemology, Biomarkers and Prevention, revised August 19, 2008.
Duffy, Christine, et. al., "Implications of Phytoestrogen Intake for Breast Cancer," CA: A Cancer Journal for Clinicians, September 2007 (57:260-77).
"Plant Compound Reduces Breast Cancer Mortality," German Cancer Research Center, www.dkfz.de (accessed November 3, 2011).
Velentzis, L.S., et. al., “Lignans and Breast Cancer Risk in Pre- and Post-Menopausal Women: Meta-Analyses of Observational Studies,” British Journal of Cancer, March 2009 (100:1492-98).
Susie Yakowicz - Susie Yakowicz is a Minnesota freelance writer whose work has appeared in dozens of publications for children and adults.
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