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Using Flax & Chia Seeds to Fight Breast Cancer

Using Flax & Chia Seeds to Fight Breast Cancer

What are Lignans and Where are They Found? Lignans are anti-carcinogenic chemical compounds found only in plant foods. The plant foods which contain the highest level of lignans are also very high in fiber. Flax and chia seeds in particular contain the highest levels of lignans. Although sesame seeds, nuts, whole grains, legumes, certain fruits and vegetables contain lignans, flaxseed contains up to 800 times more lignans than any other plant food. See the significant difference demonstrated here. Vegetarians have 8 times the levels of lignans circulating throughout their bodies compared to omnivores; vegans have notably the highest. Studies suggest that consuming foods containing high levels of lignans not only reduces the risk of breast cancer but also increases the survival of those who have already been diagnosed.

Can Lignans Help Prevent Breast Cancer? 

A study cited in Dr. Michael Greger's video Can Flax Seeds Help Prevent Breast Cancer? showed a 20-30% reduction in breast cancer risk in those women who consumed a teaspoon of ground flaxseeds per day for one year. "The reason why flaxseeds may play a role in preventing and treating breast cancer is due to an inflammatory molecule called IL-1. This molecule may help nourish tumors - assisting in their growth and reproduction. As a result, our body produces an IL-1 receptor antagonist which binds to the IL-1 receptor and blocks the action of IL-1. Activity of this protective inhibitor can be boosted with the drug Tamoxifen or by eating flax seeds. In premenopausal women, the pro-inflammatory profile of IL-1 could be counteracted by a dietary addition of a few spoonfuls of ground flax. One month of flax was able to increase the anti-inflammatory inhibitor levels by over 50%, even more than the drug. Lignans are not a magic bullet to prevent breast cancer—you can't just sprinkle some flax on your bacon cheeseburger—but as a part of a healthy diet and life-style they might help to reduce breast cancer risk in the general population."

Can Lignans Prolong a Cancer Patient's Survival?

Dr. Greger says that "The same diet that helps prevent breast cancer appears to be the same diet that's going to help prolong survival." Researchers discovered that "flaxseed appears to have the potential to reduce tumor growth in just a matter of weeks." Studies featured in his articles, Flax and Breast Cancer Survival and Breast Cancer Survival and Lignan Intake, revealed that lignan intake "is associated with improved survival among postmenopausal women with breast cancer. In fact, it appears to cut mortality risk in half!" The results of three studies conducted on thousands of women diagnosed with breast cancer reported a substantial risk-reduction of overall breast cancer mortality in post-menopausal women that consumed the highest level of lignans. Researchers concluded, "Those who had the most lignans in their blood lived the longest and tended to live the longest disease free." See the results of the studies here and here

Surprisingly, flaxseeds performed much like the breast cancer drug Tamoxifen. Tamoxifen works by "boosting the levels of angiogenesis inhibitors like endostatin which is a protein the body makes to try to starve tumors of their blood supply. When women are given Tamoxifen for 6 weeks, endostatin levels within the breast go up. The same thing happens when you add 3-1/2 tablespoons of ground flaxseed to their daily diet. The flaxseed wasn't as powerful as the chemo. However, the results were so exciting that researchers undertook a randomized, double-blind, placebo-controlled, clinical trial of flaxseeds in breast cancer patients." Researchers determined that "Dietary flaxseed has the potential to reduce tumor growth in patients with breast cancer. If the therapeutic index seen in this short-term study can be sustained over a long-term period, flaxseed, which is inexpensive and readily available, may be a potential dietary alternative or adjunct to currently used breast cancer drugs."

Similary, Dr. Joel Furhman adds: "Flax offers powerful protection against breast cancer. A study on flaxseed followed women for up to 10 years and found a 51% reduced risk of all-cause mortality and a 71% reduced risk of breast cancer mortality. Endometrial and ovarian cancers have not been as extensively studied, but the few studies that have been conducted suggest a protective effect."

Good Sources of Plant Lignans

"Flaxseeds are the richest source of plant lignans, having about 3 times the lignan content of chia seeds and 8 times the lignan content of sesame seeds (flaxseed oil does not contain lignans — they bind to the fiber). Other plant foods on the list have about one-tenth or less the amount of lignans as sesame seeds per serving."

  • Flaxseeds (85.5 mg/ounce)
  • Chia seeds (32 mg/ounce)
  • Sesame seeds (11.2 mg/ounce)
  • Kale (curly; 1.6 mg/cup)
  • Broccoli (1.2 mg/cup)

Lignans Reduce Circulating Sex Hormones - Reducing the Risk of Death from Hormone Sensitive Cancers

According to Dr. Fuhrman's article Foods That Fight Breast Cancer, "Lignans are phytochemicals that are structurally similar to the mammalian estrogen, estradiol. They are modified by bacteria in the digestive tract into enterolignans. Enterolignans are structurally similar to estrogen and can bind to estrogen receptors. Enterolignans inhibits aromatase and estradiol production in general, lowering serum estrogen levels. This capability allows lignans to have either a weak estrogenic activity or block the actions of estrogen in the body. For this reason, plant lignans are classified as phytoestrogens. There has been much interest in the potential contribution of lignan-rich foods to reduce the risk of hormone-related cancers.Plant lignans also increase concentration of a sex hormone binding globulin, which blunts the effects of estrogens. Women with breast cancer who began consuming flaxseed regularly showed significant tumor cell death after only one month. When 48 postmenopausal women consumed 7.5 grams/day of ground flax seeds for 6 weeks, then 15 grams for 6 weeks - a significant decrease in estradiol, estrone, and testosterone were noted. Overweight and obese women had the greatest decrease. Likewise, women eating more flaxseeds with higher levels of circulating lignans were found to have a 42% reduced risk of death from postmenopausal breast cancer and a dramatic (40 percent) reduction in all causes of death."

More information on how the American diet raises sex hormones can be found herehere, and here. To see how a high-fiber plant-based diet removes excess sex hormones from our bodies, click here and here.

Antibiotics Negatively Affects the Beneficial Properties of Lignans

Dr. Fuhrman's article, Fighting Breast Cancer with Flax and Chia Seeds explains the important relationship between antibiotic use and how it negatively affects the beneficial properties of lignans. As mentioned above, "Plant lignans are modified by bacteria in the human digestive tract into enteroligans. It is important to recognize the role of healthy bacteria in this process, because antibiotics can destroy beneficial bacteria in the gut resulting in long-term reduction in enteroligans. Eating commercial meats exposes us to antibiotics, as does the overuse and inappropriate prescribing by physicians."

Dr. Greger advises women to use antibiotics judiciously in his Flaxseeds and Breast Cancer Prevention video. "A few days on antibiotics dramatically drops our body's ability to make these anticancer compounds [enterolignans] from the plants that we eat, and it can take weeks for our gut bacteria to recover. This 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 confounding their good bacteria's ability to take full advantage of all the plants they were eating." More information on antibiotics here.

Frequently Asked Questions

Answers to your questions regarding where to buy flaxseeds, how to grind and store them, daily dosage, and many others can be found here - Answers to Common Questions about Flaxseed.


Just the Flax Ma`am - "Not only are flax seeds the richest source of lignans, they are an excellent source of iron, zinc, copper, calcium, protein, omega-3 essential fatty acids, potassium, magnesium, folate, soluble fiber (which can lower our cholesterol and triglycerides) and boron (which is a trace mineral important for optimum bone health.) It's good for men too. Flax seeds were recently compared to a leading pharmacological treatment for enlarged prostates. A new study found they both work just as well, yet flax seed didn't come with adverse side effects. Side effects from flax include: improves our cholesterol and blood sugar, controls our blood pressure and helps control hot flashes." However, Dr. Greger cautions not to use flax "during the last two trimesters of pregnancy, as preliminary data suggests flax use may increase the risk of preterm delivery."

For more information regarding the health benefits from flax and chia seed, click on the following links:

(1)  Dr. Carney's Cancer Pinterest Board

(2)  Flaxseeds for Prostate Cancer

(3)  Treating Breast Pain with Flax Seeds

Michael Greger MD Links

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