Saturday Aug 2, 2014 (foodconsumer.org) -- Scientists at University of Toronto in Toronto, Canada published a review to suggest that supplementation with flaxseed and its phytoestrogen lignans can prevent and even help treat breast cancer.

According to the review, the majority of animal studies indicate that 2.5 to 10% flaxseed supplemented diet or the equivalent amount of lignans or oil ( α-linolenic acid) reduces breast cancer growth.

In the dose of 10%, flaxseed and equivalent lignans increase the efficacy of tamoxifen (80 mg per day) while in the dose of 4%, flaxseed oil increases the efficacy of trastuzumab/Herceptin (2.5 mg/kg) against breast cancer.

In addition to animal studies, observational studies show that flaxseed and lignan intake, urinary excretion, or serum levels are correlated with reduced risk of breast cancer, particularly in postmenopausal women.

To be exact, lignans may reduce the risk of breast cancer, and all-cause mortality by 33 to 70% and 40 to 53%, respectively, without reducing the effectiveness of tamoxifen.

Clinical trials too reveal that using flaxseed in a dose of 25 grams with 50 mg linans per day for 32 days reduces tumor growth in breast cancer patients and using lignans in a dose of 50 mg per day for one year reduce risk in prememopausal women.

The authors say flaxseed and its lignans fight breast cancer by decreasing cell proliferation and angiogenesis and increasing apoptosis via the modulation of estrogen metabolism and estrogen receptor and growth factor receptor signaling.

The review concludes "More clinical trials are needed but current overall evidence indicates that FS and its components are effective in the risk reduction and treatment of breast cancer and safe for consumption by breast cancer patients."  (David Liu)

Mason JK, Thompson LU.  Flaxseed and its lignan and oil components: can they play a role in reducing the risk of and improving the treatment of breast cancer?  Appl Physiol Nutr Metab. 2014 Jun;39(6):663-78.