Foods That Fight Cancer™
Flaxseed, flaxseed oil and linen are all products of flax, one of the first crops to be domesticated. Flaxseed has long been used for nutritional and medicinal purposes.
Today, it is being touted for many health benefits and researchers are studying flaxseed and its oil to sort through the many claims.
What's in Flaxseed?
Flaxseed is an excellent source of magnesium, manganese and thiamin, and fiber; a good source of selenium; and provides protein and copper, too.
- Lignans: flaxseed is a particularly rich source of these plant estrogens
- Dietary fiber: One serving, about 4 tablespoons of ground flaxseed, contains more than 7 grams of fiber.
- Alpha-linolenic acid (ALA): about half of the fat in flaxseed is this plant form of omega-3 fat.
- Gamma-tocopherol: a form of vitamin E
Flaxseed oil provides alpha-linolenic acid and both alpha- and gamma-tocopherol, two forms of vitamin E. It is not a source of fiber, selenium or the other nutrients noted above. It does not naturally contain lignans, though some brands contain added lignans.
Flaxseed, Hens and Ovarian Cancer: Scientist in the Spotlight – from AICR's Cancer Research Update
Is flaxseed and effective way to reduce blood cholesterol? – From AICR HealthTalk
For Health Professionals and Educators: Flaxseed & Breast Cancer: The Take-Home (PDF) - Excerpted from AICR InDepth: Flaxseed and Breast Cancer (Join the AICR HPE eCommunity to access the full paper as well as other HPE resources, tools, and discounts on AICR materials.)
Full Glossary for Foods That Fight Cancer
The Cancer Research
The link between flaxseed and/or lignan to cancer risk is relatively well-studied. Most research has focused on flaxseed’s effects on breast cancer. Emerging areas of study include its impact on cancers of the prostate and colon.
Current Evidence: AICR/WCRF Expert Report and its Updates (CUP)
Flaxseed is high in dietary fiber. After a systematic review of the global scientific literature, AICR/WCRF weighed the strength of the evidence linking dietary fiber to cancer development. The comprehensive report found strong – probable – evidence that foods containing dietary fiber DECREASE the risk of colorectal cancer
Evidence categorized as "probable" means there is strong research showing a causal relationship to cancer – either decreasing or increasing the risk. The research must include quality human studies that meet specific criteria and biological explanations for the findings. A probable judgement is strong enough to justify recommendations.
Source: AICR/WCRF. Diet, Nutrition, Physical Activity and Cancer: A Global Perspective, 2018.
Dietary fiber seems to play a role in lowering cancer risk through its ability to provide a feeling of satiation, which could help with weight control. (Excess body fat is a cause of 12 cancers.) Healthful bacteria in the colon may also use dietary fiber to produce substances that protect colon cells.
Studies do not support fears that flaxseed could increase incidence or recurrence of breast cancer.
Studies related to flaxseed also focus on its ALA (alpha-linolenic acid). ALA is a form of omega-3 fat that is converted into another omega-3 fat, called EPA (eicosapentaenoic acid) for short. EPA is a source of protective, anti-inflammatory compounds. Only a small proportion of ALA is converted into EPA; yet the relatively small amounts of flaxseed commonly used in studies have been shown to significantly increase EPA levels.
Flaxseed are also well studied for their lignans, which are phytoestrogens, a weak form of estrogen. There was some concern that consuming flaxseed may interfere with cancer medications, such as tamoxifen, that interfere with or block estrogen. There are no human studies as of yet, but animal studies have shown that flaxseed does not interfere with the actions of common breast cancer medications (see below).
Open Areas of Investigation: Laboratory Research
In animals, flaxseed, lignans and flaxseed oil decrease several different growth factors, and they slow tumor growth and the ability to spread both estrogen receptor-positive (ER+) and -negative (ER-) breast cancer. In limited animal studies, flaxseed does not interfere with actions of tamoxifen or trastuzumab (medications used for breast cancer treatment) and may even enhance their effectiveness.
In other animal studies, flaxseed and its oil decrease markers of inflammation, decrease number and size of colon cancer tumors, and inhibit growth and spread of prostate cancer.
Open Areas of Investigation: Human Studies
In one small month-long trial of post-menopausal women with newly diagnosed breast cancer, daily flaxseed decreased cancer cell growth. In several studies of healthy women consuming flaxseed daily, estrogen levels decreased or estrogen shifted to that of the relatively inactive form. The result was less estrogen in the form that seems to promote breast cancer growth. However, studies show some unexplained variability, which may partly reflect effects of individual differences in hormones, overall diet and genetics.
Population studies are not clear about the impact of ALA on prostate cancer risk, but most recent overall analyses show no significant effect. In a study of men with prostate cancer who either ate flaxseed, followed a low-fat diet or did both for about 30 days before surgery, each strategy reduced cancer cell growth compared to a control group, although the combination strategy produced best results.
Because we don’t have research regarding the effects of flaxseed in children or women who are pregnant or breastfeeding, researchers suggest caution for these groups.
In the Kitchen
Flaxseed comes in many forms: Flaxseed (either whole or ground), flaxseed meal (some of the natural oil is removed and has the texture of cornmeal), flaxseed flour (more finely ground than the meal) and flaxseed oil (plain or with added lignans).
- Whole flaxseed provides plenty of fiber, but our bodies can't digest it enough to access its other healthful components. Ground flaxseed offers more potential health benefits, but it doesn't stay fresh as long as whole flaxseed.
- Buy whole flaxseed to grind in a coffee or spice grinder.
- If ground flaxseed or flaxseed meal is more convenient, buy either type, refrigerated or in a vacuum-sealed package.
- Flaxseed oil is quite perishable. Buy it in refrigerated opaque bottles.
- Store whole flaxseed up to a year in an airtight container in a dry, cool cabinet.
- Store ground flaxseed in an airtight container in the refrigerator up to 30 days or in freezer up to four months.
- Add ground flaxseed to hot or cold cereal, yogurt or smoothies.
- Sprinkle ground flaxseed on salads or on top of cooked vegetables for a nutty flavor.
- Include ground flaxseed in baked muffins or other quick breads.
- Flaxseed may decrease absorption of medications, so take it one hour before or two hours after any prescription or non-prescription medicine. Talk to your physician or healthcare provider about use if taking fish oil, omega-three supplements or anticoagulant medications.
- Drizzle flaxseed oil on salads or vegetables or in smoothies. Do not cook with flaxseed oil.
Flaxseed and Blueberry Pancakes
- 3/4 cup buckwheat flour
- 3/4 cup whole-wheat flour
- 2 Tbsp. ground flaxseed
- 2 tsp. baking powder
- 1 tsp. baking soda
- 1/2 tsp. salt
- 1 cup skim or low fat buttermilk
- 3/4 cup skim milk
- 2 large eggs
- 1 Tbsp. canola oil
- 1 Tbsp. honey
- 2 cups blueberries (rinsed and set aside)
- Vegetable cooking spray
- Pure maple syrup as desired
In large bowl combine flours, flaxseed, baking powder, baking soda and salt. In separate bowl mix together buttermilk, skim milk, eggs, oil and honey.
Pour egg mixture into dry ingredients and stir just until batter is lightly mixed together. (If the batter appears too thick, add a dollop more of skim milk to thin.) Lumps are okay and over mixing makes for hard pancakes. Fold in blueberries.
Preheat large skillet over medium heat. Spray skillet with cooking spray. Use about 1/4 cup of batter for each pancake. Cook for about 2 to 3 minutes per side on medium or medium-high heat. The pancakes are ready to flip when bubbles start to appear. Turn over only once and when golden brown. You will have enough for 4–6 generous servings, and any leftovers can be frozen for a mid-week treat.
Makes 6 servings
Per serving: 220 calories, 6 g total fat (1 g saturated fat), 33 g carbohydrate, 9 g protein, 6 g dietary fiber, 600 mg sodium.
Below are answers to some of the most frequently asked questions we get asked.
Which fruits and vegetables should I be eating?
Eat as many different vegetables and fruits as you can. Variety is the key to obtaining the many protective phytochemicals. Each vegetable and fruit has its own profile of health-promoting substances.
The phytochemicals found in cantaloupe are different from those in broccoli or leeks or cherries. Try to include a lot of colors on your plate. Aim to eat some bright red, green, orange, blue, purple and yellow vegetables and fruits each day.
Should I buy organic foods whenever possible?
There are many reasons to eat organic foods, but currently, there is no convincing evidence that shows a difference between organic and conventionally grown foods related to cancer risk. Studies show pesticide residues on conventionally grown foods are almost always within safety tolerance limits.
If you are concerned about pesticide residues and can afford to spend more, organic produce may be a choice for you. Eating generous servings of a large variety of veggies and fruits - whether organic or not will benefit your health. The advantages of including more vegetables and fruits in your diet outweigh the potential risks from pesticides.
Can grilled meats really cause cancer?
Lab studies show that exposing meats to direct flame, smoke and intense heat (like when you grill or broil) can cause the formation of carcinogens (cancer-causing substances). Cooking methods that involve less heat, such as microwaving, baking, steaming and poaching, do not promote the formation of these substances.
Several strategies you can use to cut carcinogen formation on meat include marinating, flipping frequently, removing excess fat from meat before cooking, and microwaving for part of the cooking time. So for delicious and healthful options, try grilling vegetables, veggie burgers and fruit slices and cut down on meat, fish and poultry.
- Bergman Jungestrom, M., L.U. Thompson, and C. Dabrosin, Flaxseed and its lignans inhibit estradiol-induced growth, angiogenesis, and secretion of vascular endothelial growth factor in human breast cancer xenografts in vivo. Clinical cancer research : an official journal of the American Association for Cancer Research, 2007. 13(3): p. 1061-7.
- Chen, J., et al., Flaxseed and pure secoisolariciresinol diglucoside, but not flaxseed hull, reduce human breast tumor growth (MCF-7) in athymic mice. The Journal of nutrition, 2009. 139(11): p. 2061-6.
- Wang, L., J. Chen, and L.U. Thompson, The inhibitory effect of flaxseed on the growth and metastasis of estrogen receptor negative human breast cancer xenograftsis attributed to both its lignan and oil components. International journal of cancer. Journal international du cancer, 2005. 116(5): p. 793-8.
- Adolphe, J.L., et al., Health effects with consumption of the flax lignan secoisolariciresinol diglucoside. The British journal of nutrition, 2010. 103(7): p. 929-38.
- Chen, J., et al., Dietary flaxseed interaction with tamoxifen induced tumor regression in athymic mice with MCF-7 xenografts by downregulating the expression of estrogen related gene products and signal transduction pathways. Nutrition and cancer, 2007. 58(2): p. 162-70.
- Chen, J., et al., Flaxseed alone or in combination with tamoxifen inhibits MCF-7 breast tumor growth in ovariectomized athymic mice with high circulating levels of estrogen. Experimental biology and medicine, 2007. 232(8): p. 1071-80.
- Mason, J.K., J. Chen, and L.U. Thompson, Flaxseed oil-trastuzumab interaction in breast cancer. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2010. 48(8-9): p. 2223-6.
- Saggar, J.K., et al., Dietary flaxseed lignan or oil combined with tamoxifen treatment affects MCF-7 tumor growth through estrogen receptor- and growth factor-signaling pathways. Molecular nutrition & food research, 2010. 54(3): p. 415-25.
- Bommareddy, A., et al., Effects of dietary flaxseed on intestinal tumorigenesis in Apc(Min) mouse. Nutrition and cancer, 2009. 61(2): p. 276-83.
- Jenab, M. and L.U. Thompson, The influence of flaxseed and lignans on colon carcinogenesis and beta-glucuronidase activity. Carcinogenesis, 1996. 17(6): p. 1343-8.
- Nagel, J.M., et al., Dietary walnuts inhibit colorectal cancer growth in mice by suppressing angiogenesis. Nutrition, 2011.
- Lin, X., et al., Effect of flaxseed supplementation on prostatic carcinoma in transgenic mice. Urology, 2002. 60(5): p. 919-24.
- Thompson, L.U., et al., Dietary flaxseed alters tumor biological markers in postmenopausal breast cancer. Clinical cancer research : an official journal of the American Association for Cancer Research, 2005. 11(10): p. 3828-35.
- Haggans, C.J., et al., Effect of flaxseed consumption on urinary estrogen metabolites in postmenopausal women. Nutrition and cancer, 1999. 33(2): p. 188-95.
- Haggans, C.J., et al., 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, 2000. 9(7): p. 719-25.
- Sturgeon, S.R., et al., Effect of flaxseed consumption on urinary levels of estrogen metabolites in postmenopausal women. Nutrition and cancer, 2010. 62(2): p. 175-80.
- McCann, S.E., et al., Changes in 2-hydroxyestrone and 16alpha-hydroxyestrone metabolism with flaxseed consumption: modification by COMT and CYP1B1 genotype. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology, 2007. 16(2): p. 256-62.
- Sturgeon, S.R., et al., Effect of dietary flaxseed on serum levels of estrogens and androgens in postmenopausal women. Nutrition and cancer, 2008. 60(5): p. 612-8.
- Demark-Wahnefried, W., et al., Flaxseed supplementation (not dietary fat restriction) reduces prostate cancer proliferation rates in men presurgery. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology, 2008. 17(12): p. 3577-87.
- Carayol, M., P. Grosclaude, and C. Delpierre, Prospective studies of dietary alpha-linolenic acid intake and prostate cancer risk: a meta-analysis. Cancer causes & control : CCC, 2010. 21(3): p. 347-55.
- Simon, J.A., Y.H. Chen, and S. Bent, The relation of alpha-linolenic acid to the risk of prostate cancer: a systematic review and meta-analysis. The American journal of clinical nutrition, 2009. 89(5): p. 1558S-1564S.
- Berquin, I.M., I.J. Edwards, and Y.Q. Chen, Multi-targeted therapy of cancer by omega-3 fatty acids. Cancer letters, 2008. 269(2): p. 363-77.
- Harper, C.R., et al., Flaxseed oil increases the plasma concentrations of cardioprotective (n-3) fatty acids in humans. The Journal of nutrition, 2006. 136(1): p. 83-7.
- Flaxpage, North Dakota State University Library.http://www.ag.ndsu.edu/agnic/flax/history.htm