Researchers are working hard to determine what may help prevent, detect, and eventually cure breast cancer. The good news is that not all methods involve drugs and other medical treatments. Some scientists are turning to the kitchen pantry for answers. Here’s more about how flaxseed can prevent and help treat breast cancer.

Breaking Down Breast Cancer

About 1 in 8 women in the United States will be diagnosed with invasive breast cancer during their lifetime. Thanks to the decline in hormone replacement therapies after menopause, breast cancer rates have decreased since the year 2000. Still, the disease is second to lung cancer in cancer-related deaths among women.

Early detection and screening have helped survival rates climb since the late 1980s. There are currently more than 2.8 million breast cancer survivors in the United States alone. Now, science suggests that something as simple as incorporating flaxseed into your diet may help ward off breast cancer and even slow tumor growth.

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What Are Flaxseeds?

Along with being a tasty food addition to food, flaxseed is particularly rich in alpha-linolenic acid (ALA). The American Institute for Cancer Research (AICR) shares that flaxseed is a good source of the following:

  • magnesium
  • manganese
  • thiamin
  • fiber
  • selenium
  • omega-3 fatty acids
  • protein
  • copper

You can consume flaxseed in a few different forms:

  • Whole seeds have lots of fiber, but they’re difficult for the body to digest. You can grind them using a coffee grinder or food processor, but the meal will perish quickly.
  • Ground flaxseed or flaxseed flour is a convenient alternative sold at many grocery stores. However, some brands remove some of the natural oils in the production process.
  • Flaxseed oil (FSO) is available at many health food stores. Some brands don’t contain lignans and others may add them back in. The oil isn’t meant for cooking.

Adding flaxseed to your diet is easy. People add flaxseed to smoothies, yogurt, and cereal. You can sprinkle it on just about anything that’s edible.

What the Science Says

In a study published by Nutrition and Cancer, researchers found that the ALA in flaxseed may have the power to reduce the growth of certain breast cancer cells. They added the ALA to cancer cells and monitored for changes. The cells responded well to the ALA in a variety of environments. They concluded that adding the seeds or other ALA-rich foods to your diet is a great complementary therapy for breast cancer. It’s also relatively safe and inexpensive.

The Journal of Nutritional Biochemistry published another study where flaxseed is credited with enhancing the effectiveness of the popular cancer drug trastuzumab. Researchers fed some rats a control diet. Other rats were divided into diet groups with FSO or with FSO and trastuzumab. After four weeks, the researchers found that the rats fed both the FSO and trastuzumab had a lower rate of tumor growth. The rats fed FSO only didn’t experience any change in tumor growth.

What about prevention? In a study published by Cancer Causes & Control, Canadian researchers surveyed over 6,000 women about their consumption of flaxseed and flax bread. Out of these women, 2,999 had breast cancer and 3,370 were healthy and didn’t have breast cancer. They discovered that 21 percent of the women who were healthy and didn’t have breast cancer ate flaxseed at least weekly. In other words, including flaxseed in the regular food rotation did help reduce breast cancer risk in this population.


Flaxseed may indeed be under the microscope in many labs for its potential to help with anything from cancer to menopause. How much flaxseed is enough to see results? The amount is probably less than you might think.

The AICR shares that in short-term human studies, people consumed between 1 to 4 tablespoons, or 5 to 30 grams, of ground flaxseed per day. This amount changed estrogen metabolism enough to protect against breast cancer.

If you’re interested in giving flax a try, your doctor may be able to give you a better idea for specifically how much to ingest.

Side Effects

Though you may think of flaxseed mostly as a food or health supplement, too much of a good thing may lead to some side effects. The most common side effects include:

  • a longer luteal phase, which is the time between ovulation and the start of your period
  • increased bowel movements
  • constipation
  • gas

Use caution if you suspect you may be allergic to flaxseed. Some people have reported anaphylaxis after ingestion. Flax contains what are called “phytoestrogens.” So, if you have estrogen receptor-positive breast cancer, speak with your doctor before using flaxseed.

Speaking with Your Doctor

Flaxseed has the potential to be a great complementary therapy in breast cancer treatment. It may even help prevent the disease in the first place. However, the seeds alone will not shrink tumors, stop cancer from spreading, or eliminate your symptoms. More research needs to be done on humans to assess its full health benefits and potential to prevent and treat breast cancer.

It’s important you speak with your doctor before using flaxseed in combination with your current treatment plan. At this stage, studies on cancer are more focused on animals than on humans. Additional work needs to be done to assess the true effectiveness of flaxseed and how safe it is for humans.

Flaxseed can slow the absorption of prescription and nonprescription medications you may be taking. You’ll also want to speak with your doctor if you take fish oil or anticoagulants like aspirin, Plavix, or Coumadin. Tell your doctor about your use of flaxseed if you’re undergoing any radiological procedures. It may affect your results for certain tests.