Flax Seeds & Breast Cancer Prevention

Flax Seeds & Breast Cancer Prevention
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Young women at high risk for breast cancer given just a teaspoon of ground flax seeds a day showed fewer precancerous changes.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

A quarter-century ago, a theory was put forth as to why those eating plant-based diets have lower cancer rates. Vegetarians appeared to have up to three times the level of lignans circulating within their bodies, thanks to the grains and other plant foods they were eating, these anticancer compounds.

Back in 1980, a new compound was described in human urine, a compound X—originally thought to be a new human hormone, but later identified to be from a large group of fiber-associated compounds, widely distributed in edible plants, known as lignans.

Population studies suggest that high intake reduces breast cancer risk. But, where’s it found? Seeds, whole grains, vegetables, fruits, berries. With that kind of list of healthy foods, why isn’t this just like the fiber story, where, you know, lignan intake is maybe just a surrogate marker for healthy plant food intake?

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 good bacteria in our gut. That’s why we want to use antibiotics judiciously, because a few days on antibiotics dramatically drops your body’s ability to make these anticancer compounds from the plants we eat. And, it can take weeks for our good bacteria to recover.

That’s why women with urinary tract infections may be at higher risk for breast cancer, because every time they took a course of antibiotics, they may be stymying their good bacteria’s ability to take full advantage of all the plants they were eating—though this remains little more than a hypothesis, or educated guess, at this point.

This is the National Cancer Institute study that provided the strongest evidence to date that there may indeed be something special about the lignan 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 precancerous changes, or carcinoma in situ), or already had breast cancer in the other breast—and gave them a teaspoon of ground flax seeds every day for a year, before getting repeat needle biopsies to see if there were any changes.

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 their teaspoon of ground flax seeds.

So, what happened by the end of the year? The primary endpoint was the expression of a proliferation biomarker associated with cancer, called Ki-67. In 9 of the 45 women it went up (those in red), but in the other 80% of the women, it went down. And, overall, they found less cellular proliferation in their breast tissue, and fewer precancerous changes.

For those who don’t like the taste of flax seeds, sesame seeds may work just as well. Even though flax seeds have significantly more lignans than sesame, you appear to produce about the same amount of lignans from them—though this was comparing them whole. And, when you feed people whole flax seeds, some may not get chewed up, and may pass right through you. So, ground flax seed may be the best source, overall.

Please consider volunteering to help out on the site.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

A quarter-century ago, a theory was put forth as to why those eating plant-based diets have lower cancer rates. Vegetarians appeared to have up to three times the level of lignans circulating within their bodies, thanks to the grains and other plant foods they were eating, these anticancer compounds.

Back in 1980, a new compound was described in human urine, a compound X—originally thought to be a new human hormone, but later identified to be from a large group of fiber-associated compounds, widely distributed in edible plants, known as lignans.

Population studies suggest that high intake reduces breast cancer risk. But, where’s it found? Seeds, whole grains, vegetables, fruits, berries. With that kind of list of healthy foods, why isn’t this just like the fiber story, where, you know, lignan intake is maybe just a surrogate marker for healthy plant food intake?

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 good bacteria in our gut. That’s why we want to use antibiotics judiciously, because a few days on antibiotics dramatically drops your body’s ability to make these anticancer compounds from the plants we eat. And, it can take weeks for our good bacteria to recover.

That’s why women with urinary tract infections may be at higher risk for breast cancer, because every time they took a course of antibiotics, they may be stymying their good bacteria’s ability to take full advantage of all the plants they were eating—though this remains little more than a hypothesis, or educated guess, at this point.

This is the National Cancer Institute study that provided the strongest evidence to date that there may indeed be something special about the lignan 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 precancerous changes, or carcinoma in situ), or already had breast cancer in the other breast—and gave them a teaspoon of ground flax seeds every day for a year, before getting repeat needle biopsies to see if there were any changes.

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 their teaspoon of ground flax seeds.

So, what happened by the end of the year? The primary endpoint was the expression of a proliferation biomarker associated with cancer, called Ki-67. In 9 of the 45 women it went up (those in red), but in the other 80% of the women, it went down. And, overall, they found less cellular proliferation in their breast tissue, and fewer precancerous changes.

For those who don’t like the taste of flax seeds, sesame seeds may work just as well. Even though flax seeds have significantly more lignans than sesame, you appear to produce about the same amount of lignans from them—though this was comparing them whole. And, when you feed people whole flax seeds, some may not get chewed up, and may pass right through you. So, ground flax seed may be the best source, overall.

Please consider volunteering to help out on the site.

Images thanks to mimitalks, married w/children via flickr

Doctor's Note

Today begins my three-part video series on the role flax seeds may play in the prevention and treatment of breast cancer. I covered their role in prostate cancer in Flax Seeds vs. Prostate Cancer, and Was It the Flax Seeds, Fat Restriction, or Both?. Then, I looked at their impact upon blood sugar control (Flax Seeds vs. Diabetes) and skin health (Flax Seeds for Sensitive Skin).

When I say “why isn’t it just like the fiber story,” I’m referring to my previous video, Fiber vs. Breast Cancer. The graph comparing the lignan contents of various foods is from my video, Breast Cancer Survival and Lignan Intake. Sorry if I covered the UTI-breast cancer connection a little fast—more background on the role our good bacteria play in Flax and Fecal Flora. As I note in the Flax Seeds 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, though? I hope you’ll find my next two videos useful: Flax Seeds & Breast Cancer Survival: Epidemiological Evidence, and Flax Seeds & Breast Cancer Survival: Clinical Evidence.

For further context, also check out my associated blog posts: Treating Sensitive Skin From the Inside OutFlax and Breast Cancer Prevention; and Flax and Breast Cancer Survival.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

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