How flaxseeds fight cancer

By Shivani Raja

It is estimated that 30-40% of all cancers can be prevented by lifestyle and dietary measures alone (Donaldson, 2004). Amongst the many foods which have shown to fight cancer, flaxseeds show particularly remarkable effects. Flaxseeds, also known as linseeds, are obtained from the Linum usitatissimum plant. Nutrients in flaxseed include lignans, antioxidants, fibre, protein, and polyunsaturated fatty acids such as alpha-linolenic acid (ALA), or omega-3 (Brazier, 2020). 

Lignans, a group of plant polyphenols, are compounds of particular interest when it comes to fighting cancer. Flaxseed is the richest source of lignans, containing more than 300 mg per 100 g serving. Lignans are a major class of phytoestrogens, which have been associated with a decreased breast cancer risk (Lowcock et al., 2009). In one study, mice stimulated with chemical carcinogens to induce cancer were administered a diet including flaxseed in its lignan fraction. Tumour size was seen to significantly decrease following the flaxseed diet (Thompson et al., 1996).

Other researchers have tested flax seed and its effect on prostate cancer. One study involved men following a low-fat diet with 30g flaxseed/day for 6 months before undergoing a repeat biopsy. Following the flaxseed-supplemented period, a statistically significant decrease in tumour proliferation rates was seen in comparison to the subjects first biopsies. Of the 15 men who participated, two saw such great results that a repeat biopsy was deemed unnecessary (Wahnefried et al., 2004). Another study involving mice found that a diet supplemented with 5% flax inhibited the growth and development of prostate cancer (Donaldson, 2004).

Analysis of nine flaxseed-based studies revealed that flaxseed oil alone provides little benefit. Flaxseed oil is stripped of its lignans during production, hence flaxseed in its whole or ground form is the preferred method of consumption (Donaldson, 2004). Ground flaxseeds are easily incorporated into one’s diet and can be added to porridge or bread dough. Flaxseeds are also a popular substitute for eggs in baking – a few tablespoons of ground flaxseed mixed with water creates a slimy gel called mucilage, similar in consistency to an egg.

Despite their remarkable effects, flaxseed consumption may be indirectly impaired for patients taking antibiotics. Studies have shown that for lignans to be effective, they must first be converted to human lignans by prebiotic bacteria in the gut. As a result, usage of antibiotic drugs, which impact the ability of prebiotic bacteria to convert lignans, may impair the effect of lignans on tumour proliferation (Greger, M., 2013).

It is evident that the lignans in flaxseed are beneficiary to reducing risk of certain cancers in addition to slowing tumour proliferation. This knowledge may be of public health importance with respect to cancer treatment and prevention.


Donaldson M. S. (2004) Nutrition and cancer: a review of the evidence for an anti-cancer diet. Nutrition journal. 3(19). Available from: 

Thompson, L. U., Rickard, S. E., Orcheson, L. J., & Seidl, M. M. (1996) Flaxseed and its lignan and oil components reduce mammary tumor growth at a late stage of carcinogenesis. Carcinogenesis. 17(6), 1373–1376. Available from:

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. 24, 813–816. Available from:

Brazier., Y. (2015) Flaxseed: health benefits, nutrition, and risks. Available from: [Accessed 4th September 2020]

Demark-Wahnefried, W., Robertson, C. N., Walther, P. J., Polascik, T. J., Paulson, D. F., & Vollmer, R. T. (2004). Pilot study to explore effects of low-fat, flaxseed-supplemented diet on proliferation of benign prostatic epithelium and prostate-specific antigen. Urology. 63(5), 900–904. Available from:

Flax Seeds & Breast Cancer Prevention. (2013). [Video]. Greger, M., 

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