New Research Reveals – Flaxseed Lignans May Lower Risk of Breast Cancer

(BeWellBuzz) Studies over the past five years have accelerated knowledge concerning possible dietary strategies for overcoming the onslaught of breast cancer. While it may be that drug companies have their own vested interests in synthetic treatments, as is popular opinion among “underground” health circles, these six studies show a perseverance among scientists to unveil whether one particular nutrient is worth your while to increase life span and decrease risk of you or a loved one being afflicted by the epidemic called breast cancer.

Lignans – the Subject of Much Excitement

Lignans are a major class of phytoestrogens, followed by isoflavones. Phytoestrogens are dietary plant-source xenoestrogens. “Xeno” means foreign, as in foreign to the body. They’re not the actual hormones, but imitators. They look and act like the endogenous hormone, but can be known to act as antagonists of estrogen. This turns out to be a (potentially) good thing. Experts believe this action of lignans may be invaluable in reducing “lifetime exposure” to estrogen, today considered a key component in developing breast cancer. But until recently, they didn’t have the empirical evidence needed to call it a breakthrough. As studies continue to develop, don’t be swayed by headlines alone. See the results straight out of the lab. Find out which foods in particular you may want to increase in your diet.  And stay tuned. As the excitement multiplies, there’ll be more where this came from soon.

Major Progress from 2008-2013

2008: Lignans & Isoflavones Reduce Risk in “Overweight,” Premenopausal Women

Lignans and isoflavones became a main focus for this epidemiological study to determine if consumption of phytoestrogens could be associated with reduced risk of breast cancer. Researchers distributed a questionnaire to determine the dietary habits of about 6,500 women in Ontario, aged 25-74 years. The study found that lignan and overall phytoestrogen consumption was associated with a reduced risk of breast cancer; but, only in overweight (BMI>25), pre-menopausal women. In post-menopausal women, there was no significant association. The research team concluded that dietary lignan may well be linked to a reduced risk of breast cancer among pre-menopausal women, but that BMI could modify the association.

2010: No Significant Associations Between Phytoestrogens and BC Risk

“EPIC-Norfolk” is the European Prospective Investigation of Cancer. In this study, EPIC researchers examined whether there was any relationship between dietary phytoestrogens and breast, prostate and colorectal cancers, again, by conducting an epidemiological study. They concluded, “No significant associations between phytoestrogen intake and breast cancer risk…were found.” According to these observations, the phytoestrogens were neither causing nor preventing the disease. However, the populations they studied had notably small amounts of phytoestrogens in their diets, overall.

It might seem, at this point, that researchers are chasing their tails; yet, interest in the xenohormones did not wane. From here, studies would move out from distant observances of populations to the lab where we could actually watch the action under a microscope.

2012: Cancer Cell Proliferation Inhibited by Flaxseed Lignans

  • Two ideas collided to provide scientists with a considerable lead. By now flaxseeds had become known for their health benefits, including heart health and even cancer prevention. Another important food on the scene was sprouts. Sprouting causes a decrease in anti-nutrients and increases macro- and micro-nutrients. Researchers at North Dakota State University took a good look at the in vitro effects of flaxseed sprouts on human breast cancer cells. Results were encouraging.

The sprouts significantly reduced growth and induced apoptosis (cell suicide) of cancer cells. This was the discovery researchers were hoping for, potentially making flaxseed sprouts part of a dietary strategy to reduce the risk of breast cancer.

  • In the same year, on the other side of the world in Pune, Maharashtra, India, scientists isolated out the lignans derived from flaxseeds. In the body, the flaxseed lignan converts to an enterolactone (EL). EL effectively inhibited cell adhesion (growing new tumors), invasion (into blood cells and the lymphatic system) and motility (ability to move); thus, blocking cancer cell proliferation.

2013: Flaxseeds Officially Associated With Reduced BC Risk

This year, the EPIC-Norfolk study came back for more. They examined and developed a database for the diets of 334,850 women, aged 35-70 years, from 10 European countries. Their disappointing conclusion: “This study shows no associations between flavonoid and lignan intake and BC risk, overall or after taking into account menopausal status and BC hormone receptors.” What could this mean? Is it possible that the observed effects in vitro are not translating en vivo?  Notably, whereas our two previous studies looked at lignans specifically from flax seeds, this epidemiological review didn’t seem to hone in on any particular food sources. Could it be that there are hidden metrics within this lump sum?

This epidemiological study in Canada looked, not at overall lignan or phytoestrogen consumption, but specifically at that from flaxseeds. After observing the diet of 2,999 with breast cancer, and 3,370 without, the team reported, “Consumption of flaxseed was associated with a significant reduction in breast cancer risk…as was consumption of flax bread.” In fact, there was a 28% reduced risk in postmenopausal women who consumed at least ¼ cup of flax seeds per month. Both post and pre-menopausal women saw a 26% risk reduction consuming one slice of flax bread…weekly. However, the latter group saw no significant reduction from eating the whole seed.

How Much You Need

Lignan food sources include bran, whole grains, seeds, nuts and legumes, but most of these only offer up to 1mg per 100g; whereas flaxseeds provide 335mg.  The study showed results with approximately 5mg/day, or 163mg/month. That’s about a teaspoon a day, with whole seeds being ineffective for premenopausal women. According to these results, both groups will do well to have a slice of flax bread/day, and postmenopausal women can meet the grade with a teaspoon of seeds daily.

Compare those results to a report published by the Flax Lignan Information Bureau, where Jocelyn Mather, R.D. says 50mg per day, or one tablespoon, is a “safe and tested daily dose.”

Sources of Flax Lignans

Flax oil is not typically a concentrated source of lignans unless the manufacturer specifies otherwise on the label. It may be that eating the seeds whole makes them less easily digestible and the active constituents less absorbed. It’s recommended that you get your flax in bread or fresh ground seeds at home. Supplements are also available.



Prepared by Rachel Ann Clark, M.S. Science Writer, BCERF, Suzanne Snedeker, Ph.D., Research Project Leader, BCERF, and Carol Devine, Ph.D, R.D., Education Project Leader, BCERF. “When reproducing this material, credit the authors and the Program on Breast Cancer and Environmental Risk Factors in New York State.” (2002) (the Program on Breast Cancer and Environmental Risk Factors in New York State)

Cotterchio M, Boucher BA, Kreiger N, Mills CA, Thompson LU. “Dietary phytoestrogen intake–lignans and isoflavones–and breast cancer risk (Canada).” (2008) PMID:17992574

Ward HA, Kuhnle GG. “Phytoestrogen consumption and association with breast, prostate and colorectal cancer in EPIC Norfolk.” (2010) PMID: 20494649

Lee J, Cho K. “Flaxseed sprouts induce apoptosis and inhibit growth in MCF-7 and MDA-MB-231 human breast cancer cells.” (2012) PMID: 22438134

Mali AV, Wagh UV, Hegde MV, Chandorkar SS, Surve SV, Patole MV. “In vitro anti-metastatic activity of enterolactone, a mammalian lignan derived from flax lignan, and down-regulation of matrix metalloproteinases in MCF-7 and MDA MB 231 cell lines.” (2012) PMID: 22842186

Zamora-Ros R, Ferrari P, González CA, Tjønneland A, Olsen A, Bredsdorff L, et al. “Dietary flavonoid and lignan intake and breast cancer risk according to menopause and hormone receptor status in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study.” (2013) PMID: 23572295

Article: “Flax seed consumption reduces breast cancer risk by 28 percent in new study.” Article by Ethan Evers. May 2013.

Flax Lignans: What You Need to Know About This Emerging Ingredient” by Jocelyn Mathern, R.D.

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