Women who are at risk for breast cancer, or who have already been diagnosed can easily feel confused and overwhelmed by the various recommendations made to them regarding their diet and supplements. Cancer patients use integrative medicine therapies more often than other patients, putting oncologists and pharmacists in a unique position. Drug to nutrient interactions is not the focus of their practices, and often the end result is misinformation to the patient, and general sweeping statements that integrative support for cancer should be avoided completely. Even research articles aimed at discounting integrative medicine make unsupported claims that perhaps flax should be avoided during breast cancer treatment (and yet don’t reference the statements) (Can, Demir, & Aydiner, 2012).

In large scale studies, flax has been associated with a 20-30% reduction in breast cancer risk for postmenopausal women (Lowcock, Cotterchio, & Boucher, 2013).

Flax is widely consumed by women being treated for breast cancer, with as many as 33% of women reporting beginning to use flax shortly after their diagnosis (Flower et al., 2013). In it’s simplest terms, flax is a phytoestrogen, or a plant with estrogen-mimicking properties. Which for women with a hormone dependent cancer, it raises the question of the use of such a plant, if it has the potential to interact with breast tissue.

Despite having estrogen-like compounds, flax seeds do not actually increase your blood levels of estrogen (Phipps, Martini, Lampe, Slavin, & Kurzer, 1993), and in fact decrease, or blunt hormone related symptoms in women undergoing breast cancer treatment. They have a slight impact on hot flashes (there are other options for this) and improve mood in women with breast cancer, and have a trend towards improving overall survival (Flower et al., 2013).

Ingesting flax through adolescence has also been shown to reduce the risk of developing breast cancer in the first place. In adolescence, rapidly growing breast tissue may be protected from environmental influences (negative xeno-estrogens) by flax, which places a protective effect on young girls who include flax in their diets (Thanos, Cotterchio, Boucher, Kreiger, & Thompson, 2006).

Through adulthood, flax alters estrogen metabolism to improve the overall picture of your circulating hormones. Similar to the broccoli family, flax improves a woman’s ratio of estrogens, leaning towards less potent, less carcinogenic forms of the hormone (Haggans, Travelli, Thomas, Martini, & Slavin, 2000). Flax appears to offer the greatest protection to women who are overweight, but the effect is also seen in women who have a healthy body mass (Cotterchio, Boucher, Kreiger, Mills, & Thompson, 2008).

The dose required to achieve a breast cancer prevention effect is relatively small, with even as little as a teaspoon showing a positive effect (Cotterchio et al., 2008). Flax can be prescribed for multiple reasons, with doses ranging from 1 tsp up to 2 heaping tablespoons per day to get the desired effect so be sure to ask us at your next appointment what the best dose would be based on your case. Most studies use flax in baked goods such as breads and muffins. We often recommend patients achieve their daily dose by adding flax to their smoothie.

Can, G., Demir, M., & Aydiner, A. (2012). Complementary and alternative therapies used by Turkish breast cancer patients undergoing chemotherapy. Breast Care (Basel, Switzerland), 7(6), 471–475. http://doi.org/10.1159/000345462

Cotterchio, M., Boucher, B. A., Kreiger, N., Mills, C. A., & Thompson, L. U. (2008). Dietary phytoestrogen intake–lignans and isoflavones–and breast cancer risk (Canada). Cancer Causes & Control: CCC, 19(3), 259–272. http://doi.org/10.1007/s10552-007-9089-2

Flower, G., Fritz, H., Balneaves, L. G., Verma, S., Skidmore, B., Fernandes, R., … Seely, D. (2013). Flax and Breast Cancer: A Systematic Review. Integrative Cancer Therapies, 13(3), 181–192. http://doi.org/10.1177/1534735413502076

Haggans, C. J., Travelli, E. J., Thomas, W., Martini, M. C., & Slavin, J. L. (2000). The effect of flaxseed and wheat bran consumption on urinary estrogen metabolites in premenopausal women. Cancer Epidemiology, Biomarkers & Prevention: A Publication of the American Association for Cancer Research, Cosponsored by the American Society of Preventive Oncology, 9(7), 719–725.

Lowcock, E. C., Cotterchio, M., & Boucher, B. A. (2013). Consumption of flaxseed, a rich source of lignans, is associated with reduced breast cancer risk. Cancer Causes & Control: CCC, 24(4), 813–816. http://doi.org/10.1007/s10552-013-0155-7

Phipps, W. R., Martini, M. C., Lampe, J. W., Slavin, J. L., & Kurzer, M. S. (1993). Effect of flax seed ingestion on the menstrual cycle. The Journal of Clinical Endocrinology and Metabolism, 77(5), 1215–1219. http://doi.org/10.1210/jcem.77.5.8077314

Thanos, J., Cotterchio, M., Boucher, B. A., Kreiger, N., & Thompson, L. U. (2006). Adolescent dietary phytoestrogen intake and breast cancer risk (Canada). Cancer Causes & Control: CCC, 17(10), 1253–1261. http://doi.org/10.1007/s10552-006-0062-2