Over the years, I‘ve heard a bit about the anti-breast cancer benefits of flaxseed, but never really researched it. When today’s guest writer approached me about doing a post on just this subject, I welcomed the idea of sharing what she has learned from several studies.
Harriet Sugar Miller, guest writer, is a freelance health journalist and erst while lawyer living in Montreal. After a recurrence seven years ago of a rare, estrogen-sensitive ovarian cancer, she started devouring the research on nutrition and cancer and now shares her knowledge on Huff Post Canada and on her own site, www.eatandbeatcancer.com. Look for her digital book, coming in late fall, on dietary strategies for preventing and fighting cancer.
Know anyone who has breast cancer? Doing your best to avoid it? Then consider this: Studies are showing that flaxseed can protect against breast cancer and prolong survival in women who have it.
For more than 20 years, the grande dame of flaxseed research, Dr. Lilian Thompson of the University of Toronto, has been studying the effects of flaxseed on cancer, especially in the breast.
How does it work?
Flaxseed is rich in an omega 3 fatty acid called alpha-linolenic acid (ALA), which inhibits inflammatory chemicals that stimulate the growth of malignant cells. It’s also, of all foods, the best source of lignans, compounds that have been shown to reduce the growth and spread of cancer cells.
Lignans, in fact, are phytoestrogens–that is, estrogens from plants–and contrary to what many of us have been led to believe, plant estrogens may protect us from the stronger estrogens our bodies produce and the xenoestrogens found in environmental chemicals. How’s that?
“Phytoestrogens have been estimated to be 500-1,000 times weaker than human estrogen, says Dr. Jeanne Wallace, a PhD in nutrition who counsels cancer patients on diet and supplements. “By docking on estrogen receptors in the body, phytoestrogens may prevent activation of these receptors by our own estrogen and xenoestrogens.”
Plus, flaxseed increases Sex Hormone Binding Globulin, a compound that binds estrogen, thus potentially reducing the amount of freely circulating estrogen that can act on breast tissue.
“All estrogen, in fact, is not created equal. The liver metabolizes estrogen and changes it into different daughter compounds, which have differing effects on breast tissue. 2-OH estrogens are favorable, offering protective effects, whereas 16-OH estrogens are unfavorable, and a preponderance of 16-OH estrogen is linked with an increased risk of breast cancer,” says Wallace.
Cruciferous veggies, soy foods and fish oil shift the balance toward the good 2-OH estrogens, according to Wallace.
“So does flaxseed,” Thompson says.
“Flaxseed (10 to 25 g/daily) has been shown to increase the ratio (of 2 to 16 estrogens) in pre- and post-menopausal women, indicating a protective effect,” explains Thompson, in a chapter she wrote recently for “The Encyclopedia of Dietary Supplements.”
Other mechanisms are also possibly at work here, she adds, and include reducing the activity of enzymes such as aromatase that are involved in estrogen synthesis and the expression of some genes, proteins, hormones and other growth factors that stimulate tumors.
Let’s look at the studies thus far.
The animal studies: Several studies indicate that flaxseed has anti-cancer effects and does not promote breast tumor growth, Thompson writes, in article published this year by the US Flax Institute.
The epidemiological studies (studies of human populations with and without disease) suggest that lignans can reduce the risk of breast cancer and prolong survival of those living with it, including pre and especially postmenopausal women, she points out. High lignan intake has been associated with tumors with more favorable prognostic factors. And while lignans appear to be effective on both estrogen positive and estrogen negative tumors, one study showed they have a stronger effect on ER-PR- than on ER+PR+ ones, she says.
It’s the clinical studies in humans that are considered the gold standard, however, assuming they’re conducted at their best (i.e., subjects include a control group, are randomly allocated and double-blinded so that nobody knows if she’s taking the flaxseed or placebo.)
Several years ago, Thompson conducted the first clinical trial of flaxseed–on postmenopausal women with breast cancer. She fed 25 g flaxseed or placebo for approximately 5 weeks to women awaiting surgery. The results were promising, showing significant changes for the better in the tumors of those who ate flaxseed.
“Clinical studies on breast cancer patients or pre-menopausal women with high risk of getting breast cancer are very limited,” says Thompson, “but those that have been conducted suggest that flaxseed is able to reduce the growth of breast tumors in postmenopausal women and that SDG (the main lignan) may also reduce the risk of getting breast cancer.”
Today, several clinical trials continue to investigate the almighty seed.
For more on how you might benefit from flaxseed, read the entire article at http://eatandbeatcancer.wordpress.com/2012/08/03/anti-cancer-recipes-can-flaxseed-stave-off-breast-cancer/.
Editor’s note: If you are in active treatment for breast cancer, speak with your oncologist before adding a dietary supplement to your diet.
