- Over the past decade, soy foods have become America's
favorite health food. Newspapers, magazines, and best-selling health writers
have proclaimed the "joy of soy" and promoted the belief that
soy food is the key to disease prevention and maximum longevity.
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- The possibility that an inexpensive plant food could
prevent heart disease, fight cancer, fan away hot flashes, and build strong
bodies in far more than 12 ways is seductive. The truth, unfortunately,
is far more complex. Soy foods come in a variety of forms, including many
heavily processed modern products. Even good forms of soy foods must be
eaten sparingly-the way they have been eaten traditionally in Asia. Most
important, many respected scientists have issued warnings stating that
the possible benefits of eating soy should be weighed against the proven
risks. Indeed, thousands of studies link soy to malnutrition, digestive
distress, immune-system breakdown, thyroid dysfunction, cognitive decline,
reproductive disorders and infertility-even cancer and heart disease.
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- Americans rarely hear anything negative about soy. Thanks
to the shrewd public relations campaigns waged by Archer Daniels Midland
(ADM), Protein Technologies International (PTI), the American Soybean Association,
and other soy interests, as well as the Food and Drug Administration's
(FDA) 1999 approval of the health claim that soy protein lowers cholesterol,
soy maintains a "healthy" image.
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- This article is written for parents who need to know
the risks of feeding soy formula to infants, or soy milk and other soy
foods to growing children. It's designed for prospective mothers and fathers
who need to know the links between soy foods, infertility, and birth defects.
Finally, it will serve anyone considering soy as a preventive for menopausal
symptoms, osteoporosis, cancer, heart disease, or other ills.
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- How Much Soy Do Asians Really Eat?
- Those who dare to question the benefits of soy tend to
receive one stock answer: Soy foods couldn't possibly have a downside because
Asians eat large quantities of soy every day and consequently remain free
of most western diseases. In fact, the people of China, Japan, and other
countries in Asia eat very little soy. The soy industry's own figures show
that soy consumption in China, Indonesia, Korea, Japan, and Taiwan ranges
from 9.3 to 36 grams per day.1 That's grams of soy food, not grams of soy
protein alone. Compare this with a cup of tofu (252 grams) or soy milk
(240 grams).2 Many Americans today think nothing of consuming a cup of
tofu, a couple glasses of soy milk, handfuls of soy nuts, soy "energy
bars," and veggie burgers. Infants on soy formula receive the most
of all, both in quantity and in proportion to body weight.
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- In short, there is no historical precedent for eating
the large amounts of soy food now being consumed by infants fed soy formula
and vegetarians who favor soy as their main source of protein, or for the
large amounts of soy being recommended by Dr. Andrew Weil, Dr. Christiane
Northrup, and many other popular health experts.
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- What's more, the rural poor in China have never seen-let
alone feasted on-soy sausages, chili made with Textured Vegetable Protein
(TVP), tofu cheesecake, packaged soy milk, soy "energy bars,"
or other newfangled soy products that have infiltrated the American marketplace.
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- The Right Stuff
- The ancient Chinese honored the soybean with the name
"the yellow jewel" but used it as "green manure"-a
cover crop plowed under to enrich the soil. Soy did not become human food
until late in the Chou Dynasty (1134-246 B.C.), when the Chinese developed
a fermentation process to make soybean paste, best known today by its Japanese
name, miso.3 Soy sauce-the natural type sold under the Japanese name shoyu-began
as the liquid poured off during the production of miso. Two other popular
fermented soy foods, natto and tempeh, entered the food supply around 1000
A.D. or later in Japan and Indonesia, respectively.
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- Tofu came after miso. Legend has it that, in 164 B.C.,
Lord Liu An of Huai-nan, China-a renowned alchemist, meditator, and ruler-discovered
that a purée of cooked soybeans could be precipitated with nigari
(a form of magnesium chloride found in seawater) into solid cakes, called
tofu. In Japan, as in China, tofu was rarely served as a main course anywhere
except in monasteries. Its most popular use was-and is-as a few bland little
blocks in miso soup or fish stock.
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- The Chinese almost never ate boiled or baked soybeans
or cooked with soy flour except in times of famine. Modern soy products
such as soy protein isolate (SPI), TVP, soy-protein concentrate, and other
soy-protein products made using high-tech industrial processes, were unknown
in Asia until after World War II.4
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- Contrary to popular belief, neither soy milk nor soy
infant formula is traditional in Asia. Soy milk originated as a byproduct
of the process of making tofu; the earliest reference to it as a beverage
appeared in 1866.5 By the 1920s and 1930s, it was popular in Asia as an
occasional drink served to the elderly.6-8 The first person to manufacture
soy milk in China was actually an American-Harry Miller, a Seventh Day
Adventist physician and missionary.9
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- The first soy infant formulas in China were developed
in the 1930s and have never been widely used.10-14 Today, babies in Asia
are almost always breastfed for at least the first six months, then switched
to a dairy-based infant formula. Orphans and others who cannot be breastfed
by a wet nurse are fed from birth on dairy formulas.15
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- Claims that soybeans have been a major part of the Asian
diet for more than 3,000 years, or from "time immemorial," are
simply not true.
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- Processing Matters
- Soy in the West has been a product of the industrial
revolution-an opportunity for technologists to develop cheap meat substitutes,
to find clever new ways to hide soy in familiar food products, to formulate
soy-based pharmaceuticals, and to develop a renewable, plant-based resource
that could replace petroleum-based plastics and fuels.
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- For years, the soy protein left over from soy-oil extraction
went to animals and poultry. Now that food scientists have discovered inexpensive
ways to improve or disguise the color, flavor, "bite characteristics,"
and "mouth feel" of soy protein-based products, soy is being
aggressively marketed as a "people feed." Although the newer
refining techniques yield blander, purer soy proteins than the "beany,"
hard-to-cover-up flavors of the past, the main reason that soy foods now
taste and look better is the lavish use of unhealthy additives such as
sugar and other sweeteners, salt, artificial flavorings, colors, and monosodium
glutamate (MSG).
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- Soy now lurks in nearly 60 percent of the foods sold
in supermarkets and natural food stores. Much of this is "hidden"
in products where it wouldn't ordinarily be expected, such as fast-food
burgers and Bumblebee canned tuna. Soy is also a key ingredient in ersatz
products with names like Soysage, Not Dogs, Fakin Bakin, Sham Ham, and
TofuRella, which have been named after and made to look like the familiar
meat and diary products they are intended to replace.
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- There's nothing natural about these modern soy protein
products. Textured soy protein, for example, is made by forcing defatted
soy flour through a machine called an extruder under conditions of such
extreme heat and pressure that the very structure of the soy protein is
changed. Production differs little from the extrusion technology used to
produce starch-based packing materials, fiber-based industrial products,
and plastic toy parts, bowls, and plates.16
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- The process of making soy protein isolate (SPI) begins
with defatted soybean meal, which is mixed with a caustic alkaline solution
to remove the fiber, then washed in an acid solution to precipitate out
the protein. The protein curds are then dipped into another alkaline solution
and spray-dried at extremely high temperatures. SPI is then often spun
into protein fibers using technology borrowed from the textile industry.
These refining processes remove "off flavors," "beany"
tastes, and some of the worst flatulence-producing components. They improve
digestibility, but vitamin, mineral, and protein quality are sacrificed,
and levels of carcinogens such as nitrosamines are increased.17-22 SPIs
appear in so many products that consumers would never guess that the Federation
of American Societies for Experimental Biology (FASEB) decreed in 1979
that the only safe use for SPIs was for sealers for cardboard packages.23
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- Antinutrients and Toxins in Soy
- Scientists who have studied the use of soy protein in
animal feeds over the years have discovered a number of components in soy
that cause poor growth, digestive distress, and other health problems.24-27
To list just a few of these: Protease inhibitors interfere with protein
digestion and have caused malnutrition, poor growth, digestive distress,
and pancreatitis.28 Phytates block mineral absorption, causing zinc, iron,
and calcium deficiencies.29-34 Lectins and saponins have caused leaky gut
and other gastrointestinal and immune problems.35-36 Oxalates-surprisingly
high in soy-may cause problems for people prone to kidney stones and women
suffering from vulvodynia, a painful condition marked by burning, stinging,
and itching of the external genitalia.37, 38 Finally, oligosaccharides
give soy its notorious reputation as a gas producer. Although these are
present in all beans, soy is such a powerful "musical fruit"
that the soy industry has identified "the flatulence factor"
as a major obstacle that must be overcome for soy to achieve full consumer
acceptance.39, 40
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- Apologists for soy dismiss such claims, saying that food
processing and home cooking remove most of these antinutrients. In fact,
modern processing removes most of them, but not all. The levels of heat
and pressure needed to remove all protease inhibitors, for example, severely
damage soy protein and make it harder to digest. The trick is to eliminate
the most antinutrients while doing the least damage to the soy protein.
Success varies widely from batch to batch.41-44
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- For years, the soy industry tried to improve the quality
of animal feeds by finding better ways to get rid of these undesirable
antinutrients. Having failed, they routinely supplement animal feeds heavily
with vitamins, minerals, and methionine, a sulfur-containing amino acid
that is low in soy. Even so, makers of animal chows are still limited in
the amount of soy they can add without causing growth and fertility problems.
Food processors making soy-protein products for people may or may not add
these supplements. Generally, calcium and vitamin D are added to soy milk
so it can compete with dairy products.
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- Today, the soy industry has switched tactics-from trying
to remove unwanted antinutrients to trying to convince people that they
are actually a good thing. Protease inhibitors, saponins, and lectins are
being touted as curers of cancer or lowerers of cholesterol, while phytates
are being recommended for their ability to remove toxic minerals such as
cadmium and excess iron from the body.45-51 Although some of these uses
look promising, it is important to note that researchers are not achieving
these successes using regular soy foods. Most take carefully extracted
components and administer them in carefully measured and monitored pharmaceutical
doses. News headlines to the contrary, there is no reason to think that
just eating a lot of soy foods will do the trick.
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- Soy Allergens
- Soy is one of the top eight allergens that cause immediate
hypersensitivity reactions such as coughing, sneezing, runny nose, hives,
diarrhea, difficulty swallowing, and anaphylactic shock. Delayed allergic
responses are even more common and occur anywhere from several hours to
several days after the food is eaten. These have been linked to sleep disturbances,
bedwetting, sinus and ear infections, crankiness, joint paint, chronic
fatigue, gastrointestinal woes, and other mysterious symptoms.52, 53
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- Soy allergies are on the rise for three reasons: the
growing use of soy infant formula (now 20 to 25 percent of the formula
market), the increase in soy-containing foods in grocery stores, the possibility
of the greater allergenicity of genetically modified soybeans.54 Although
severe reactions to soy are rare compared to reactions to peanuts, tree
nuts, fish, and shellfish, soy has been underestimated as a cause of food
anaphylaxis. Recently, after a young girl in Sweden suffered an asthma
attack and died after eating a hamburger that contained only 2.2 percent
soy protein, Swedish researchers looked into a possible soybean connection.
They concluded that the soy-in-the-hamburger case was not a fluke, and
that minute amounts of soy "hidden" in regular food had caused
four of the total of five deaths caused by allergic reactions in Sweden
between 1993 and 1996. Of the children who suffered fatal attacks, all
had been able to eat soy without any adverse reactions right up until the
dinner that caused their deaths.55 According to the Swedish Ministry of
Health and Social Affairs, children at highest risk are those who suffer
from peanut allergies and asthma; parents of such children should make
every effort to eliminate all soy from their children's diets.56
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- Soy and the Thyroid: A Pain in the Neck
- More than 70 years of human, animal, and laboratory studies
show that soybeans put the thyroid at risk. The chief culprits are the
plant hormones in soy known as phytoestrogens or isoflavones.57-59 The
United Kingdom's Committee on Toxicology has identified several populations
at special risk: infants on soy formula, vegans who use soy as their principal
meat and dairy replacements, and men and women who self-medicate with soy
foods and/or isoflavone supplements in an attempt to prevent or reverse
menopausal symptoms, cancer, or heart disease.60
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- Infants with congenital hypothyroidism need 18 to 25
percent higher doses of thyroxine drug than usual if they are bottle-fed
with soy formula.61 Likewise, adults who boost their thyroid with drugs
such as Synthroid while also eating thyroid-inhibiting foods such as soy
put extreme stress on their thyroids. Toxicologist Michael Fitzpatrick,
PhD, points out that this is the way that researchers induce thyroid cancers
in laboratory animals.62
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- Soy and Reproduction: Breeding Discontent
- Scientists have known since the mid-1940s that phytoestrogens
can impair fertility. Fertility problems in cows, sheep, rabbits, cheetahs,
guinea pigs, birds, and mice have all been reported.63, 64 Although scientists
discovered only recently that soy lowers testosterone levels,65 tofu has
traditionally been used in Buddhist monasteries to decrease the libido,
and by Japanese women to punish straying husbands. Humans and animals appear
to be the most vulnerable to the effects of soy estrogens prenatally, during
infancy and puberty, during pregnancy and lactation, and during the hormonal
shifts of menopause. Of all these groups, infants on soy formula are at
the highest risk because of their small size and developmental phase, and
because formula is their main source of nutrient.66, 67
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- A crucial time for the programming of the human reproduction
system is right after birth-the very time when bottles of soy formula are
given to many non-breastfed babies. Normally during this period, the body
surges with natural estrogens, testosterones, and other hormones that are
meant to program the baby's reproductive development from infancy through
puberty and into adulthood. For infants on soy formula, this programming
may be interrupted.68-70
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- Male infants experience a testosterone surge during the
first few months of life and produce androgens in amounts equal to those
of adult men. So much testosterone at such a tender age is needed to program
the body for puberty, the time when a male's sex organs should develop
and he should begin to express male characteristics such as facial and
pubic hair and a deep voice. If receptor sites intended for the hormone
testosterone are occupied by soy estrogens, however, appropriate development
may never take place.71-74 To date, most of the evidence damning soy formula
can be found only in animal studies, because investigations in which humans'
sex hormone levels are lowered experimentally cannot ethically be done.
However, in the years since soy formula has been in the marketplace, parents
and pediatricians have reported growing numbers of boys whose physical
maturation is either delayed or does not occur at all. Breasts, underdeveloped
gonads, undescended testicles (cryptorchidism), and steroid insufficiencies
are increasingly common. Sperm counts are also falling.75-79
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- Soy formula is bad news for girls as well. Natural estrogen
levels approximately double during the first month of life, then decline
and remain at low levels until puberty. With increased estrogens in the
environment in the diet, an alarming number of girls are entering puberty
much earlier than normal.80-82 One percent of girls now show signs of puberty,
such as breast development or pubic hair, before the age of three. By the
age of eight, 14.7 percent of Caucasian girls and 48.3 percent of African
American girls had one or both of these characteristics.83 The fact that
blacks experience earlier puberties than whites is not a racial difference
but a recent phenomenon.84, 85
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- Most experts blame this epidemic of "precocious
puberty" on environmental estrogens from plastics, pesticides, commercial
meats, etc., but some pediatric endocrinologists believe that soy is a
contributor.86 Of all the estrogens found in the environment, soy is the
likeliest explanation of why African American girls reach puberty so quickly.
Since its establishment in 1974, the federal government's Women, Infants
and Children (WIC) program has provided free infant formula to teenage
and other low-income mothers while failing to encourage breastfeeding.
Because of perceived or real lactose intolerance, black babies are much
more likely to receive soy formula than Caucasian babies.
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- Early maturation in girls heralds reproductive problems
later in life, including amenorrhea (failure to menstruate), anovulatory
cycles (cycles in which no egg is released), impaired follicular development
(follicles failing to mature and develop into healthy eggs), erratic hormonal
surges, and other problems associated with infertility. Because the mammary
glands depend on estrogen for their development and functioning, the presence
of soy estrogens at a susceptible time might predispose girls to breast
cancer, another condition that is on the rise and definitively linked to
early puberty.87
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- Recently, a team of researchers headed by Brian L. Strom,
MD, studied the use of soy formula and its long-term impact on reproductive
health. They announced only one adverse finding: longer, more painful menstrual
periods among women who'd been fed soy formula in infancy.88 Dr. Strom's
conclusion that the results were "reassuring" made newspaper
headlines all over the world, though the data in the body of the report
were anything but. Indeed, data left out of the headlines and buried in
the report revealed higher incidences of allergies and asthma, and higher
rates of cervical cancer, polycystic ovarian syndrome, blocked fallopian
tubes, and pelvic inflammatory disease.89 Although thyroid damage from
soy formula has been the principal concern of critics for decades, the
researchers excluded thyroid function as a subject for study. Not surprisingly,
this study was funded in part by the infant-formula industry.
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- Most of the fears concerning soy formula have focused
on estrogens. There are other problems as well, notably much higher levels
of aluminum, fluoride, and manganese than are found in either breastmilk
or dairy formulas.90-96 All three metals have the potential to adversely
affect brain development. Although trace amounts of manganese are vital
to the development of the brain, toxic levels accrued from ingestion of
soy formula during infancy have been found in children suffering from attention-deficit
disorders, dyslexia, and other learning problems.97, 98
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- Soy apologists sometimes argue that the plant hormones
in soy formula could not possibly be harmful because Japanese women eat
a lot of soy products and so must have high levels of phytoestrogens in
their breastmilk. Researchers, however, have measured the soy isoflavones
in breastmilk and found them low even in vegetarian women who consume copious
quantities of tofu, soy milk, soy protein shakes, and other soy foods.99-101
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- Limited evidence, however, suggests that vegetarian women
who eat a lot of soy foods during pregnancy may put their infants at risk
in terms of their future reproductive health, fertility, and possibly increased
risk of breast cancer. All of the problems that have befallen infants on
soy formula, as well as estrogen-related birth defects, have occurred (in
animal studies, at least) to the offspring of mothers who were given high
doses of soy during pregnancy.102 One of these birth defects that has been
linked to vegetarian diets in humans is hypospadias, a developmental disorder
in which the opening of the penis is located on the underside of the shaft.103
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- Until soy estrogens are definitely linked to reproductive-tract
abnormalities, infertility, and other health problems in humans, most health
authorities recommend that we "wait and see." This could be a
terrible mistake.
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- In the 1940s and 1950s, another estrogen, diethylstilbestrol
(DES), was widely given to Western women early in their pregnancies in
a misguided attempt to prevent miscarriage. That fact is relevant not only
because DES bears a striking structural similarity to some plant estrogens-including
soy isoflavones-but because it took more than 20 years before the full
spectrum of harmful effects was observed.104, 105
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- DES is 100,000 times more potent than soy phytoestrogens.
However, the large quantities of phytoestrogens in soy products are more
than enough to counteract their lower potency. When the effects of isoflavones
in fetal and neonatal animals have been studied, they have paralleled those
observed in human infants exposed to DES.106, 107 Recent studies indicate
that the soy isoflavone known as genistein may be even more carcinogenic
than DES.108
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- Yet the belief persists that soy hormones are "safe"
because they are "weak" and "natural." Although the
soy industry has claimed that soy estrogens are anywhere from 10,000 to
1,000,000 times weaker than the human estrogen estradiol, the correct figure
is only 1,200 times as weak.109 Though this still sounds quite weak, it
is not-because of the quantity of these estrogens ingested by infants on
soy formula, and by children and adults who eat soy every day. These individuals
consume far more soy estrogens than were ever part of a traditional diet
in Asia. The average isoflavones intake in China is 3 milligrams, or 0.05
mg per kilogram of body weight.
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- In Japan, the figures range from 10 to 28 mg, or 0.17
to 0.47 isoflavones per kg of body weight. In contrast, infants receiving
soy formula average 38 mg of isoflavones, which comes to a shocking 6.25
mg/kg of body weight. Compare that dose to the 0.47 mg/kg per day fed to
healthy Japanese adult men and women who experienced thyroid suppression
after just three months-or to the 0.75 mg/kg of isoflavones fed to American
women who experienced hormonal changes sufficient to skew their menstrual
cycles after just one month.110 Although children and teenagers are less
vulnerable than infants, their young bodies are still developing, and highly
vulnerable to endocrine-system disruption by soy. And soy has been shown
to pass through the placentas of pregnant women to their unborn babies.
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- Meanwhile, the jury is still out on whether soy might
help alleviate menopausal symptoms or prevent osteoporosis and breast cancer.
The soy industry's top scientists, convened at the Fifth International
Symposium on the Role of Soy in the Preventing and Reversing Chronic Disease
(held in Orlando, Florida, September 21-24, 2003), conceded that the data
are confusing and contradictory, with some studies suggesting that soy
might be helpful, and others showing that soy contributes to osteoporosis
and promotes breast cancer.
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- What's certain is that the levels of soy estrogens that
might possibly have a beneficial effect on hormonally related diseases
have been proven to jeopardize the health of the thyroid. Likewise, the
25 grams of soy protein per day touted by the FDA to lower cholesterol
(see sidebar, "Boon to the Industry: The FDA's Soy Protein Health
Claim") is very likely to harm the thyroid, and thus increase one
of the risk factors for heart disease.
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- The bottom line is that the safety of soy foods has yet
to be proven, and that human beings have become guinea pigs in what Daniel
M. Sheehan, formerly senior toxicologist with the FDA's National Center
for Toxicological Research, has called a "large, uncontrolled and
basically unmonitored human experiment."111
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- http://www.mothering.com/articles/growing_child/food/soy_story.html
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