From Nutrition Science News
By Jack Challem
Ask women about their greatest health fears, and many will rank
breast cancer close to the top, even though they're five times
more likely to die from heart disease. Yet conventional medicine,
in the quest to prevent breast cancer, has accomplished little
more than a dog chasing its own tail. The drug tamoxifen, for
instance, helps many women with breast cancer, but they pay the
price of an increased risk of endometrial cancer. 
Medicine would do much better concentrating on genuine
prevention--especially through nutrition.
For the past several years, researchers have been trying to
unravel the mysteries of the so-called breast cancer genes, named
BRCA1 and BRCA2. Women who inherit either of these genes run a 90
percent risk of developing breast cancer. But having these genes
isn't necessarily bad. BRCA1 and BRCA2 also control milk
production and can be highly advantageous to nursing mothers
(e.g., by enabling women to lactate during famines). 
Furthermore, there's some evidence that properly functioning
BRCA1 and BRCA2 genes actually prevent cancer. One study found
that normal BRCA1 genes can inhibit tumor growth. [3,4]
Despite all the attention being given to the BRCA1 and BRCA2
genes, only 10 percent of all breast cancers can be linked to
them, according to Donald C. Malins, Ph.D., D.Sc., director of
molecular epidemiology at the Pacific Northwest Research
Foundation in Seattle. Malins, a highly respected researcher,
blames most breast cancers on generic free-radical damage to
breast cell DNA. Such DNA damage, he says, is likely what makes
the BRCA1 and BRCA2 genes turn bad as well.
But, Malins points out, women don't have to passively wait for
the damage to occur.  "Diets rich in antioxidants that
neutralize free radicals may well be helpful at early stages of
DNA damage," he says. Later, more powerful and concentrated
antioxidants may be necessary to repair the damage, he adds.
One interesting though little-considered marker for
breast cancer is catalase. If a person's body fails to produce
enough of this important enzyme, the risk of breast cancer--for
both males and females--can skyrocket. But the medical profession
fails to routinely screen people for it.
Catalase converts hydrogen peroxide into water and oxygen.
Without sufficient catalase (or another enzyme called glutathione
peroxidase), hydrogen peroxide spins off large numbers of
hydroxyl radicals--considered the most dangerous type of free
According to Kunihiko Ishii, M.D., of the Okayama University
Medical School, Japan, an estimated 3 million Japanese men and
women carry a genetic defect that prevents them from making
adequate amounts of catalase. If a comparable (0.23) percent of
Americans shared this genetic trait, more than 6 million people
in this country would also suffer from low-catalase production.
People with insufficient catalase have serious trouble quenching
the free radicals that damage their DNA.
In recent experiments, Ishii and his colleagues showed that micewith low or no catalase were especially prone to cancer. He then
fed a strain of zero-catalase mice diets either enriched or
deficient in vitamin E. He used vitamin E because it is a
well-known antioxidant, and some studies have found it protective
against breast cancer. 
Without vitamin E, the zero-catalase mice had an 82 percent
incidence of breast cancer. With vitamin E supplementation, the
incidence was only 47 percent. Vitamin E also delayed the onset
of breast cancer from 9 to 14 months, or by 35 percent. Aside
from demonstrating the protective role of vitamin E in breast
cancer, Ishii also showed that serious genetic defects may be
partially overcome with supplements.
Unlike many scientists who hesitate to extrapolate animal
research to people, Ishii took a very clear stand. He wrote that
"vitamin E intrinsically has a protective effect against the
development of mammary tumors, and this may apply not only to the
... mouse, but also to humans."  So based on Ishii's
comments, there is definitely hope for the future.
The Antitumor Vitamin
There's more good news about vitamin E and breast cancer. A
common type of vitamin E supplement, known as vitamin E
succinate, has been shown in cell-culture studies and animal
experiments to inhibit the growth of various types of cancer.
This trait appears unique to vitamin E succinate, which can be
identified on bottles by its chemical name "d-alpha tocopherylxx
Several cell-culture experiments have shown that vitamin E
succinate halts the growth of cancerous cells, including breast
cancer cells. This form of vitamin E seems to halt cancer cell
proliferation by protecting "transforming growth factor-b" that
regulates cell growth. 
But vitamin E succinate works in other ways as well. In a recent
paper, researchers from NCI reported that vitamin E succinate
prompts apoptosis (programmed cell death) in breast cancer cells.
"An advantage for using vitamin E and/or vitamin E derivatives in
human cancer therapy is its low level of toxicity in vivo," wrote
Maria C. Birchenall-Roberts, Ph.D., of NCI. 
Of course, cell-culture studies are a long way from human trials.
But Gerald Shklar, D.D.S., of the Harvard University Dental
School, has taken the next step. He used a toxic chemical to
induce oral cancer in hamsters, then fed them vitamin E
succinate. The vitamin E prevented cancer growth, and its
mechanism was particularly surprising. It inhibited angiogenesis
(the growth of tumor-feeding blood vessels), thus suggesting yet
another way vitamin E may help treat breast cancer. 
Citrus and Genistein Lower Breast Cancer Risk
Fresh fruit juices have occasionally been used as alternative
cancer treatments, and a recent series of cell-culture and animal
experiments confirms their value. Kenneth K. Carroll, Ph.D., a
biochemist at the University of Western Ontario, London, Canada,
investigated the effect of orange and grapefruit juices--and some
of the nutritional flavonoids they contain--on breast cancer.
He exposed laboratory rats to a cancer-causing chemical, then fed
them large amounts of orange and grapefruit juice. The juices
slowed the development of breast cancer in the rats. Next,
Carroll gave similar rats the flavonoids naringin or naringenin,
found in grapefruit juice, and these also slowed the development
of breast cancers. Orange juice, containing the flavonoid
hesperetin, had a similar beneficial effect.
Carroll also found that hesperetin and naringenin inhibited the
proliferation of breast cancer cells in cell-culture experiments.
Furthermore, when each of the citrus flavonoids were combined
with quercetin, another flavonoid, the combination had a
synergistic effect and "suppressed the proliferation of the cells
at much lower concentrations than either compound
On another note, researchers have long known that Asian women,
who eat large amounts of soy foods, have a relatively low risk of
breast cancer. Their risk of breast cancer, however, increases
when they move to the United States and begin eating low-soy
Soy foods contain a particular group of flavonoids, called
isoflavones, that have very weak estrogenic activity. One of
these isoflavones, genistein, has only 1/1000th the hormonal
activity of true estrogen. What happens, researchers believe, is
that genistein competes directly against estrogen for cell
receptors and can block the more powerful estrogen, which is
known to increase cancer risk.
Based on animal experiments, a woman who begins eating soy foods
as a child might have a lower risk of breast cancer as an adult.
Coral A. Lamartiniere, Ph.D., a researcher at the University of
Alabama, Birmingham, added either genistein or a placebo to the
diets of prepubescent laboratory rats. Later, she exposed all of
the rats to a cancer-causing chemical.
The animals given genistein developed almost 50 percent fewer
mammary tumors during their lifetimes compared with those given
the placebo, according to Lamartiniere's article in
Carcinogenesis. They also had slightly longer menstrual
cycles, a factor which is also associated with lower breast
cancer risk in women. 
Although genistein modulates the effects of estrogen, it may
reduce the risk of breast cancers in still other ways. For
example, genistein inhibits tyrosine protein kinase, an enzyme
that promotes cancer cell proliferation. It also blocks
angiogenesis and induces cancer cell death. 
Genistein is a potent antioxidant--more powerful than other
isoflavones--and, as discussed above, dietary antioxidants are
strongly associated with cancer prevention.  In
addition, genistein stimulates the body's production of its own
antioxidant enzymes, including glutathione peroxidase, catalase
and superoxide dismutase (SOD). 
What all of this research shows is that common nutrients, in
concentrated form, can prevent many types of DNA damage that lead
to cancer.  In practical terms, this means women
don't have to wait in fear of breast cancer, or hope for the
distant promise of high-tech and high-priced gene therapy.
Nutritional supplements qualify as a form of natural gene therapy
that women can use today to protect the genes they were
Jack Challem, based in Aloha, Ore., has been writing about
vitamin research for more than 20 years and publishes The
Nutrition Reporter newsletter.
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