THE LIGHT AND DARK SIDES OF SOY
Excerpted from What Your Doctor May Not Tell You about Breast Cancer by John R. Lee, M.D., Dr. David Zava and Virginia Hopkins
How to eat soy so that it helps.
Today, it's all but impossible to find a health-related magazine or TV
show that doesn't shout out the benefits of soy foods for the prevention of
menopause symptoms, breast and other cancers, heart disease and osteoporosis.
In the past decade, the soy industry has poured hundreds of millions of dollars
into the research, marketing and advertising of soy foods, and it has been
well rewarded for its efforts. However, while we agree that certain soy foods,
eaten in moderation, can be a healthy addition to the diet, we believe that
women who are eating soy with every meal, or even every day, may be damaging
their health. Soy has its good side, but it also has its bad side, which has
been largely ignored by those rushing to cash in on this nutritional fad.
Traditional Asian soy foods such as tofu, tempeh, and miso have been a dietary
staple in that part of the world for centuries, and they are increasingly found
in Western diets. Western food manufacturers have also developed a slew of
new soy foods, using these little beige beans as an ingredient in protein powders,
hot dogs, burgers, cheese, cereals, sports bars, and other convenience foods.
Soy milk, texturized soy protein, and soy cheese have been touted as nutritious
alternatives to cow's milk products and meat. Supplement companies create pills
from soy phytochemicals and advertise them as natural medicines for relief
of menopause symptoms, or as protection against cancer, heart disease, or osteoporosis.
Soy powders are sold as supposedly healthy meal alternatives. Some of these
products are good for you, and some are best avoided. In this chapter you'll
find out how to eat soy foods so they enhance your health….
SOY AND MENOPAUSE
With all that we know about the pitfalls of conventional medicine's treatment
of women in menopause, it makes sense that women are turning to natural approaches
to relieve menopausal discomforts. The beneficial effects of estrogen on these
discomforts are indisputable, but as women become more informed they see that
the risks especially of breast cancer may be too great to justify its use.
Others stop using conventional HRT because of side effects, and look to natural
remedies to help them control their menopause symptoms.
This growing interest in natural solutions for treating menopausal symptoms
has prompted the food and supplement industries to develop alternatives to
conventional pharmaceutical estrogens such as Premarin. The soy foods industry
has been poised to benefit most from this search for natural remedies for menopause
because of soy's high phytoestrogen content.
The lay press and the soy industry have widely promoted the message that soy
phytoestrogens act, in effect, as surrogate estrogens. Such a message gives
women the impression that they can use soy to naturally relieve symptoms of
falling estrogen levels at menopause. While the research does show that isoflavones
behave like estrogens in the body the conclusion that they are all the medicine
a woman needs to help her through menopause is not borne out by recent clinical
studies on soy and menopausal symptoms.
Soy phytoestrogens have very little effect on vasomotor symptoms such as hot
flashes, night sweats and vaginal dryness. In one comprehensive study from
the Bowman Gray School of Medicine in North Carolina, researchers looked at
the effects of soy phytoestrogens on women aged 45 to 55 with menopausal symptoms.
This study was big news because the women who took a phytoestrogen-rich soy
supplement reported a 50 percent decrease in the severity of their hot flashes.
What most news stories didn't mention, however, is that the placebo group reported
a 35 percent reduction. Furthermore, this study showed small reductions in
the severity of hot flashes, but none on their frequency. In
other words, these women were having just as many hot flashes as they did before
they added soy foods or supplements, but the intensity of those hot flashes
were diminished. While decreased intensity is certainly a good thing when it
comes to hot flashes, soy estrogens are clearly not as potent as many forms
of conventional estrogen replacement which often eliminate hot flashes quickly
A recent study of women with vasomotor symptoms at the Mayo Clinic showed
no benefits from soy protein isolates, which have high levels of phytoestrogens.
This has also been Dr. Zava's experience in analyzing saliva hormone level
results accompanied by detailed questionnaires; soy phytoestrogens simply don't
work well to control vasomotor symptoms. The isoflavones in soy are aromatase
inhibitors which lower the levels of estrogens made by the body, which is counter-productive
to controlling vasomotor symptoms.
Soy phytoestrogens do have the estrogenic effect of stimulating the
growth of breast cancer cells in tissue cultures. Several studies presented
at a recent soy symposium showed that soy protein isolates stimulate the growth
of normal breast cells much the way that natural estrogens do, and of course
this would add to breast cancer risk if progesterone is not present.
To read more about how to eat soy so that it helps not hurts, please read the book, What Your Doctor May Not Tell You About Breast Cancer by John R. Lee, M.D., David Zava Ph.D., and Virginia Hopkins.