By Kaayla T. Daniel
Issue 124: May/June 2004
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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
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
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.
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.
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).
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.
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
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
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
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
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.
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.
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
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
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
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
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
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
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
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
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.
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
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.
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
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
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
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.
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
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
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. 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.
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.
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.
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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