Breast health in general, and breast malignancy in particular, are major concerns for
modern women living in Western industrialized nations. Although there are no preventive
interventions, natural or conventional, that can absolutely guarantee that a particular
woman will never manifest breast cancer, there are a number of choices women can make to
dramatically reduce breast cancer risk. Each option has its own protective effects, and
combinations of mutually-reinforcing options can offer significant protection.
Omega-3s and Breast Health
As mentioned elsewhere on this website, modern cell biology is revealing the profound
influence that cell membranes and their communication with cell nuclei have on the
expression of genes in chromosomal DNA. This influence is modulated by the epigenome, the
protein structures surrounding DNA that, in effect, turn genes "on" and "off." Moreover,
this control seems to include cancer genes (oncogenes). Cell membranes are made of dietary
fatty acids. By changing the fatty acid building blocks of cell membranes, we can change the
kind of signals sent from the cell membranes to nuclei to reduce the risk of turning on
undesirable genes. This influence of membrane fatty acids on gene expression indicates the
potential benefit of essential fatty acid nutrition in controlling tendency toward
Each type of fatty acid has its own influence on health and disease. From laboratory and
clinical evidence amassed to date, researchers are concluding that in general, omega-6 fatty
acids (found in grain fed livestock and common vegetable oils, such as corn, safflower, and
soy) have a tumor-promoting effect, while omega-3 fatty acids (as in flaxseed oil and fish
oil) seem to have a tumor-inhibiting effect.
Multi-centered clinical trials in which levels of fatty acids in fat tissue (an indicator
of long-term intake) were measured, have determined that the ratio of omega-6s to omega-3s is critical to
breast cancer risk. The lower the ratio, the higher the risk; and the higher the ratio, the
lower the risk. The benefit of omega-3s is strongly influenced by the background levels of
omega-6s. Investigators are drawing the conclusions that in general, omega-6s seem to
promote tumor growth, while omega-3s seen to inhibit tumor growth. This research supports
findings over the last twenty years that we cannot derive the full benefit of omega-3 fatty
acids until we reduce the daily intake of omega-6 fats.
Flaxseed oil for breast health
Alpha-linolenic acid (ALA), the omega-3 fatty acid in flaxseed oil, has been shown to
suppress the expression of a key breast cancer gene (oncogene HER2). Furthermore, a low
level of ALA in breast fat (adipose) tissue is associated with positive axillary (arm-pit)
lymph node status and with presence of vascular invasion. This finding suggests that ALA
may reduce the risk of metastasis in breast cancer.
How much flaxseed oil do you need to take to get the protective effects? To maximize the
benefits of whatever amount of flaxseed oil you decide to use, you must reduce the omega-6
sources and other non-omega-3 sources in your eating routine. In consultation with your
health professionals, consider taking one tablespoon of organic flaxseed oil per 100 pounds
of body weight.
Fish oil for breast health
In laboratory experiments, EPA (a major omega-3 in fish oil) reduces breast cancer tumor
cell growth and metastasis. Other experiments have demonstrated that diets containing fish oil also significantly decrease primary breast tumor growth and metastasis.
How much fish oil is sufficiently protective against malignancy? That question has not
been definitively answered as yet. However, a good place to start is the recommended level
for cardiovascular protection. That amount is sufficient fish oil to provide 1,000 mg of
combined EPA/DHA daily as you reduce disruptive omega-6 sources in your diet. If you are
suffering from chronic inflammation, the dosage should be sufficient fish oil to provide
daily 3,000 mg of combined EPA/DHA.
Flaxseed, Lignans, and Breast Health
Flaxseed and DNA
Since nuclear chromosomal DNA is where our genes reside, it is imperative that
chromosomal DNA be protected from damage that can turn on undesirable genes (e.g., cancer
genes or oncogenes) or trigger harmful mutations. Spontaneous genetic damage can arise from
replication errors, oxidative damage, background radiation, and chemical exposure.
Because whole grains, fruits, and vegetables are associated with lower rates of cancer,
scientists have compared a wide range of whole foods to discover which is most protective
against chromosomal DNA damage. Of the wide range of foods tested, researchers discovered
that flaxseed is the most protective in reducing chromosomal damage in laboratory
experiments. Investigators suggest that this dietary anti-carcinogenic effect by flaxseed
may have beneficial influence on human cancer rates.
Phyto-Estrogens: Flaxseed Lignans, and Estrogens
Today many women are aware of the link between long-term exposure to estrogens (from first
menses at puberty to menopause) and risk for breast malignancy. The reason for this
connection is the fact that the function of estrogens is to stimulate tissue to grow in
expectation of pregnancy – rebuilding the inner lining of the uterus after menses and
building up breast tissue in anticipation of the need for nursing after delivery. However,
if cancer genes have been turned on inadvertently in the affected tissue, the risk for
malignancy increases in the uterus and the breast.
It has been a concept of naturopathic doctors, nutritionists, and medical herbalists that
phyto-estrogens (plant-based compounds with very mild estrogenic effects) may be protective
against these adverse secondary influences of estrogens. The reason is the fact that
phyto-estrogens have only 2% of the potency of a woman’s own human estrogens; therefore,
these plant compounds may be able to block some of the adverse effects of human hormones
without increasing risk for malignancy.
Plant foods provide two major categories of phyto-estrogens:
- Iso-flavones (as in soybeans)
- Lignans (found in oily seeds of which flaxseed is most abundant and thoroughly researched)
Flaxseed and its lignan phyto-estrogens have the ability to reduce serum levels of steroid
hormones, such as estrogens. The effect seems to be most pronounced in obese and overweight
Estrogen Metabolism: Flaxseed Lignans vs. Soy Isoflavones
In addition to all the other work the liver has to do, one of its responsibilities is the
processing (metabolism) of steroid hormones (e.g., estrogens and testosterone) for removal
from the body. There are two biochemical pathways the liver can use to dispose of estrogens –
one produces benign, non-toxic by-products (metabolites) and the other produces metabolites
that increase breast cancer risk. It has been shown in clinical studies that, compared to
soy isoflavones, flaxseed lignans are superior in their ability to shunt the metabolism of
estrogens in the direction of the more benign pathway., This observation elevates flaxseed
to preferred status over soy as a source of phyto-estrogens for breast health.
Lignans and breast cancer risk
The relationship between serum levels of lignans and breast cancer risk is so strong that
some clinical investigators, after following high-risk women for years, have concluded that
serum levels of lignans provide an accurate indicator of breast cancer risk. That means
that the lower the long-term blood levels of lignans, the higher the breast cancer risk; and
the higher the blood levels of lignans, the lower the risk for breast malignancy.
Obesity and Breast Cancer
Obesity is being linked to increased risk for a wide range of malignancies. One of the
reasons for this adverse influence of fat tissue is the fact that fat tissue produces its
own estrogens, beyond what is produced in the ovaries and completely outside of the control
of the Endocrine System (including the hypothalamus and the pituitary gland). Fat (adipose)
cells contain an enzyme (estrogen synthase) that coverts whatever male hormones (androgens)
are circulating into female hormones (estrogens) and dumps them into the bloodstream. This
effect of fat tissue increases estrogen influence in a woman’s body over time, and thereby
increases her risk for breast cancer.
Flaxseed lignans have a protective effect against these undesirable actions of fat
tissue. Researchers believe that phyto-estrogens interact with estrogen receptors on breast
and uterine tissue in a way that blocks some of the adverse effects of estrogens, be they
human, animal, or foreign environmental chemicals (xeno-estrogens). Because plant compounds,
such as lignans, have only a small fraction of the estrogenic effect on breast and uterine
tissue that human estrogens do, the risk for malignancy is dramatically reduced. In addition,
flaxseed lignans have the ability to inhibit the activity of the fat tissue enzyme estrogen
synthase,, thereby reducing the manufacture and release of undesirable excess estrogens.
Flaxseed, Flaxseed Lignans, and Breast Malignancy
Investigators who have explored in laboratory experiments the tumor inhibiting properties
of flaxseed, as well as that of flaxseed oil and the flaxseed lignan SDG
(secoisolariciresinol diglycoside) have concluded that the anti-cancer benefits of flaxseed
arise from both the oil and lignan components.
Blood supply to tumors. In military science, it is understood that an army can move
forward in a military campaign only as far and as fast as their supply and logistical
support can keep up. The same concept applies to tumors: they can only progress to the
extent that they have new blood vessels formed to supply tumor tissues with oxygen and
nutrients. This is the reason why limiting the generation of new blood vessels
(angiogenesis) is so critical to the treatment of tumors. Vascular endothelial growth factor
(VEGF) is the compound, found outside of cells, that is believed to stimulate the growth of
new blood vessels. In laboratory experiments, it has been found that flaxseed lignans
inhibit the growth and metastasis of human breast cancer tumors, while concurrently reducing
levels of VEGF. Researchers believe that the restriction of the activity of VEGF may be one
of the mechanisms by which flaxseed lignans provide breast protective effects.
Estradiol, the potent human estrogen, has been demonstrated to stimulate the growth of
tumor cells with estrogen receptors and to increase VEGF in breast cancer. In laboratory
experiments, flaxseed lignans inhibit the growth-promoting influence of estradiol on tumor
cells and the production of VEGF.
Tumor growth. In clinical trials involving post-menopausal women with newly diagnosed
breast cancer, milled flaxseed (25 gm daily in a muffin) was able to reduce the
proliferation rate for tumor cells and increase the rate of cancer cell suicide (apoptosis).
Based on this evidence, researchers concluded that flaxseed has the potential to reduce
tumor growth in patients with breast cancer.
Laboratory experiments have revealed some very encouraging effects of flaxseed lignans with
respect to development and growth of tumors. Investigators have concluded that the flaxseed
lignan SDG has an anti-tumor effect when provided at the early promotion stage of tumor
development. Other research indicates that flaxseed and the lignan SDG may delay
progression of carcinogen-induced mammary tumor formation.
How many lignan sources do you need to get real protection?
The modern Western diet is woefully deficient in whole organic sources of lignans and
other fiber compounds. In fact, the serum concentration of lignans found to have a permanent
positive effect on breast cancer growth is greater than 10 times the serum concentrations
found in the general human population in Western industrialized nations.
Flaxseed lignans and tamoxifen
Tamoxifen is a pharmaceutical agent used to prevent breast cancer by inhibiting the
growth and development of malignant breast tissue. It has been demonstrated in laboratory
experiments that flaxseed lignans work harmoniously with tamoxifen. In fact, investigators
have concluded that lignans reinforce the inhibitory effect of tamoxifen.
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