Flaxseed: A Powerful Cancer-Fighting Food

Flaxseeds contain components—including phytoestrogens, alphalinolenic acid, and fiber—that may help improve breast cancer survival for some people. The seeds, oil, and seed meal of flaxseed can be used in a variety of ways.

Flaxseed in a spoon
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Dietary Benefits

You may be familiar with flaxseeds, as they are used as a natural laxative, a source of dietary fiber, and to help lower cholesterol.

Flaxseeds may also be beneficial for your health if you have heart disease, osteoporosis, breast cancer, and endometrial cancer.

For maximal nutrition benefit, it's recommended to consume freshly ground flaxseed. Whole seeds may pass through the system relatively undigested, and ground seeds exposed to air for prolonged periods of time are subject to oxidation, potentially negating some of their beneficial properties.

You can sprinkle no more than a total of two to three tablespoons per day on bread, cereals, soups, and salads. You can also add flaxseed oil to salad dressings or mix it with a smoothie. It must be taken with plenty of fluids, and you should increase your intake slowly to avoid bloating.

Anti-Cancer Action

Several studies have been done to determine how the phytoestrogens, which are plant-based estrogen-like compounds in flaxseeds could play a role in helping cancer.

In animal studies, it has been shown that consumption of flaxseeds may block estrogen receptors on cells within the breast tissue. This has been proposed as a potential mechanism for stopping tumor growth and preventing cell damage.

Breaking Down the Bounty

Flaxseeds are about the size of sesame seeds. The two components of flaxseeds that have been studied in relation to cancer are lignans (a phytoestrogen) and alphalinolenic acid (ALA).

Additionally, dietary fiber in flaxseeds and flaxseed oil can be beneficial for digestive functions for some people. This gastrointestinal effect can have positive effects beyond digestion.

Dietary Fiber

Freshly ground flaxseeds are a source of dietary fiber. Fiber from flaxseeds may help lower cholesterol and reduce constipation for some people.

With the relatively recent awareness that gut microflora (bacteria in your stomach and intestines) can affect everything from our moods to how well cancer treatments work, flaxseed scores a win. We've learned that it's possible to change the number and diversity of bacteria in the digestive system through our diets.

A diet high in fiber correlates with healthier gut microfloria. Fiber, including the fiber in flaxseeds, acts as a prebiotic, feeding the gut bacteria, maintaining beneficial bacteria, and keeping the bad bacteria in check.

Recent studies have found that how well a person responds to cancer immunotherapy treatment is related to a healthy diversity of the gut microflora.


Flaxseeds and sesame seeds are both great sources of lignans, a plant-based estrogen.

Lignans may act as a weak estrogen, binding to estrogen receptors on cells in breast and endometrial tissues. This action may protect cells that are susceptible to cancer-associated damage from estrogen exposure.

Alphalinolenic acid (ALA)

Alphalinolenic acid is an omega-3 fatty acid, that is not made in your body—it must come from food. Omega-3 fatty acids are polyunsaturated fats that help reduce inflammation.

When omega-3s are part of a well-balanced diet—which includes vitamin C, vitamin E beta-carotene, and selenium—the combination of nutrients may help reduce breast cancer-associated inflammation.


If you're taking flaxseed as a laxative, drink plenty of water to avoid constipation or intestinal blockage, as the seeds expand during digestion. Your body needs time to absorb the components of flaxseed, so wait a while before taking any other supplements or medications. Avoid flaxseed oil if you are allergic to flax or if you are pregnant or nursing. If you've had estrogen-receptor positive breast cancer, use flaxseed products in moderation.

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  1. Mccann SE, Thompson LU, Nie J, et al. Dietary lignan intakes in relation to survival among women with breast cancer: the Western New York Exposures and Breast Cancer (WEB) Study. Breast Cancer Res Treat. 2010;122(1):229-35. doi:10.1007/s10549-009-0681-x

  2. National Center for Complementary and Alternative Medicine, National Institutes of Health. Flaxseed and flaxseed oil. Updated November 30. 2016

  3. Oncology Nutrition DPG. Flaxseeds and breast cancer. Updated January 2014.

  4. Liu K, Lu C. Gut microbes modulate host response to immune checkpoint cancer immunotherapy. Translational Cancer Research. 2018. 7(Suppl 5):S608-S610. doi:10.21037/tcr.2018.05.37