START A PETITION 27,000,000 members: the world's largest community for good

Flaxseeds for Breast Cancer Prevention

Just a teaspoon of ground flaxseeds a day may protect against breast cancer.

In 1980 a new compound was discovered in human urine. Researchers called it compound X. Originally it was thought to be a new human hormone, but it was soon identified as part of a large group of fiber-associated compounds widely distributed in edible plants known as lignans.†Vegetarians have about twice the level of lignans circulating within their bodies given their greater intake of plant foods. Since population studies suggested that high intake of lignans reduces breast cancer risk, perhaps lignans are one of the reasons those eating plant-based diets have lower cancer rates.

Where are lignans found most in the diet? Seeds, whole grains, vegetables, fruits and berries. Since these are all really healthy foods in their own right, though, maybe lignan intake is just acting as a surrogate marker for whole plant food intake? (Like the fiber story I detail in Fiber vs. Breast Cancer). Well, in a petri dish lignans do directly suppress the proliferation of breast cancer cells but only after the plant lignans are converted into human lignans by the bacteria in our gut. (More detail in Flax and Fecal Flora).

That’s why we want to use antibiotics judiciously. A few days on antibiotics dramatically drops our body’s ability to make these anticancer compounds from the plants that we eat, and it can take weeks for our gut bacteria to recover. That may be why women with urinary tract infections have been found to be at higher risk for breast cancer. Every time they took a course of antibiotics they may have been stymying their good bacteria’s ability to take full advantage of all the plants they were eating.

In the above video I profile the National Cancer Institute study that provides the strongest evidence to date that there might indeed be something special about this class of phytonutrients for breast cancer prevention. They took a bunch of young women at high risk for breast cancer, meaning they had a suspicious breast biopsy showing either atypical hyperplasia or carcinoma in situ, or already had breast cancer in the other breast. They gave them a teaspoon of ground flaxseeds every day for a year before getting a repeat needle biopsy to see if there was any change.

Yes, there are lignans in sesame seeds, nuts, whole grains, legumes, certain fruits, and veggies, but they’re most concentrated in flax seeds. They could have instead asked women to eat ten cups of strawberries a day for a year, but they’d probably get better compliance with just a teaspoon of flax.

So what happened by the end of the year? The primary end point was the expression of a proliferation biomarker associated with cancer called ki-67. In 9 of the 45 women it went up, pictured in red in the video, but in the other 80% of the women it went down. And, indeed, on average they found less cellular proliferation in their breast tissue and fewer precancerous changes.

For those that don’t like the taste of flaxseeds, sesame seeds are also high in lignans. Even though flaxseeds have significantly more lignans than sesame, you appear to produce about the same amount of lignans from them. This was, however, comparing them whole. When people are fed whole flaxseeds, some may not be chewed up and can pass right through you. So ground flaxseed may be best overall. As I note in the Flaxseeds For Sensitive Skin video, ground flax stays fresh even at room temperature for at least a month.

What if you or a loved one has already been diagnosed with breast cancer? See my follow-up videos:

In health,
Michael Greger, M.D.

PS: If you havenít yet, you can subscribe to my videos here and watch my full 2012 year-in-review presentation†Uprooting the Leading Causes of Death.

Image credit: mimitalks, married w/children / Flickr

What Should Women Eat to Live Longest?
Prevent Breast Cancer by Any Greens Necessary
Mushrooms For Breast Cancer Prevention

Read more: Health, Cancer, Diet & Nutrition, Eating for Health, General Health, Videos, Women's Health, , , , ,

have you shared this story yet?

go ahead, give it a little love

Dr. Michael Greger

A founding member of the American College of Lifestyle Medicine, Michael Greger, M.D., is a physician, author, and internationally recognized speaker on nutrition, food safety, and public health issues. Currently Dr. Greger serves as the Director of Public Health and Animal Agriculture at The Humane Society of the United States. Hundreds of his nutrition videos are freely available at


+ add your own
7:50AM PDT on May 30, 2013

I take it for my Lupus.

12:25AM PDT on May 27, 2013

Thanks for sharing!

9:49PM PDT on May 21, 2013

Good in bread, too.

3:40PM PDT on May 19, 2013

Well, time to search for that jar of flax seeds I've put away and forgot about.

12:54PM PDT on May 19, 2013

I love Flaxseed and have it in my oatmeal every morning. I actually got my sister eating it too; she was diagnosed with breast cancer this past year. I keep my ground flax in the freezer and it stays nice and fresh. There is a cookbook out I want to recommend to others, called “Kicking Cancer in the Kitchen” by Annette Ramke & Kendall Scott. Their website has some more great info as well. I bought it for my sister when she was diagnosed, and there are some really great and healthy recipes in there. I'm going to have to look again to see if there are any using Flaxseed.

12:44PM PDT on May 19, 2013

Thank-you. I used to take flaxseed oil, but have switched to ground flaxseed, a couple of months ago. Good stuff!

12:29AM PDT on May 19, 2013

Flax seeds are in my diet on a daily basis. However, it's good to hear that ground flax remains fresh for at least a month.....

9:31PM PDT on May 18, 2013


6:49PM PDT on May 18, 2013

We must be careful about claims like this

5:58PM PDT on May 18, 2013


add your comment

Disclaimer: The views expressed above are solely those of the author and may not reflect those of
Care2, Inc., its employees or advertisers.

people are talking

All OK as a diet supplemented treat.

Exercise is good, but it involves a whole lot more than "muscle-building." At least this article em…

very useful information. thanks!

Kefir is delicious, thank you.


Select names from your address book   |   Help

We hate spam. We do not sell or share the email addresses you provide.