Does Soy Have a DARK SIDE - Natural Health

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Does Soy Have a DARK SIDE - Natural Health

 

 

> Natural Health: Does Soy Have a DARK SIDE?-

> http://www.findarticles.com/cf_0/m0NAH/2_29/53929987/p1/article.jhtml -

>

> Does Soy Have a DARK SIDE?

> Author/s: Sally Eauclaire Osborne

> Issue: March, 1999

>

> You've heard about the research touting soy's benefits, but some experts

say

> you haven't heard the whole story.

> ON THE LAND OF HEALTH FOODS, SOY IS KING. It's considered a near-perfect

> protein, one that's packed with compounds that can fight disease and

promote

> health. Soy's plant estrogens--isoflavones--are said to prevent cancer,

cut

> cholesterol, reverse osteoporosis, and wipe out menopausal symptoms. Earl

> Mindell, Ph.D., a registered pharmacist and author of Earl Mindell's Soy

> Miracle (Simon & Schuster, 1995), joins many nutritionists and doctors

when

> he says, " Anyone who wants to live longer should be eating this food. "

> Yet a few scientists think the coronation of soy as a miracle food is

> premature. They claim that while some soyfoods offer distinct health

> benefits, others pose health risks, particularly to people who consume

large

> amounts of soy. Critics cite four main potential dangers associated with

> eating too much soy or too much of certain kinds of soyfoods: One,

soyfoods

> can disrupt the functioning of the thyroid gland: two, soyfoods can

> interfere with the digestion of proteins: three, they contain substances

> that rob the body of minerals: and four, soy's isoflavones may upset

hormone

> balance.

> How the Controversy Began

> As early as 1917 researchers noted that soybeans had to be heat-treated in

> order for soy-fed rats to grow--presumably because soy contains a

substance

> that inhibits digestion. Over the years, scientists have reported other

> potential problems with soy In this decade two women--Mary G. Enig, Ph.D.,

a

> fellow at the American College of Nutrition and a nutritional biochemist

in

> Silver Spring, Md., and Sally W. Fallon, editor of the Price-Pottenger

> Nutrition Foundation Journal, which reports on the dietary habits of

> indigenous peoples--sought to make sense of these studies.

> In 1995, Enig and Fallon believed they had found enough research to

support

> certain charges against soy, particularly the concerns over thyroid

> inhibition, protein digestion, and mineral absorption. They wrote an

article

> for the September 1995 issue of Health Freedom News--a publication of the

> nonprofit health advocacy group called National Health Federation in

> Monrovia, Calif.--in which they detailed these charges and cited dozens of

> scientific studies.

> Enig and Fallon do not believe all soy products are equally suspect. " Some

> beneficial factors may appear in soyfoods prepared by traditional

> fermentation methods, such as miso, tempeh, and natto, " Fallon says.

> Fermentation involves a slow chemical change triggered by bacteria, molds,

> or yeast. Enig and Fallon state that this process eliminates soy's

problems

> by making it more digestible and deactivating potentially harmful

> substances. They see more problems with nonfermented soyfoods: tofu,

> soymilk, texturized soy protein, and soy protein isolate. (For

definitions,

> see " Soy Glossary " on the next page.)

> Since the 1995 article, other researchers have reported that soy may

> adversely affect hormones and have questioned the claims that soy fights

> cancer (see " Genistein and Cancer: Enemies or Allies? "

>

> After reviewing a few of the studies on the adverse effects of soy, Alan

R.

> Gaby, M.D., a nutrition professor at Bastyr University in Kenmore, Wash.,

> says, " I certainly think caution is reasonable. Soy is probably beneficial

> in moderate amounts, possibly harmful in larger amounts. "

>

> Meanwhile, as researchers debate these charges, some nutritional

counselors

> have begun to suspect that soy may be to blame for the low energy,

digestive

> disturbances, hypothyroidism, infertility, and other ailments they see in

> clients.

>

> Brian R. Clement, director of the Hippocrates Health Institute, a raw

foods,

> vegan clinic in West Palm Beach, Fla., says, " People come to us

unshakeable

> in their belief that tofu, soy burgers, soy this, soy that are all good

for

> you. They're not. " Clement says his clinic staff has found it three times

> more difficult to bring the blood chemistry of people on a heavy soy diet

to

> optimal levels than to improve the blood chemistry of people who eat

little

> or no soyfoods. (Blood chemistry, according to Clement, includes

everything

> from iron levels to pH balance.)

>

> A number of scientists disagree with Clement. Mark Messina, Ph.D., a

former

> program director in the diet and cancer branch of the National Cancer

> Institute and co-author of The Simple Soybean and Your Health (Avery,

1994),

> responds, " I'm not saying those stories are poppycock, but it bothers me

as

> a scientist when anecdotal data is given too much credence. The problems

> might not be from soy. What else were those people consuming? The way to

> know is to look at published scientific studies. Researchers who have

looked

> hard for adverse effects haven't found many. "

>

> Below we take a look at the research and at what some experts think about

> the charges lodged against soy.

>

> Does Soy Disrupt the Thyroid?

>

> The thyroid gland in the front of the neck secretes thyroid hormones and

> controls metabolism. Several scientists have linked soy consumption to

> suppressed thyroid function, including hypothyroidism (in which the gland

> produces not enough hormones). Researchers at the North Shore University

> Hospital-Cornell University Medical College in Manhasset, N.Y., found that

> children with autoimmune thyroid disease had consumed significantly more

> soy-based milk formulas than had their healthy siblings and other healthy

> children. These findings were published in the Journal of the American

> College of Nutrition in 1990. One year later, a 1991 Japanese study

> published in the Japanese journal Nippon Naibunpi gakkai Zasshi showed

that

> soybeans could trigger goiters (an enlargement of the thyroid) and

> hypothyroidism. Half of the 17 healthy adult participants who ate 30 g of

> pickled roasted soybeans a day for three months developed a small goiter

> and/or experienced hypothyroidism. One month after the study was

completed,

> all thyroids had returned to normal size and hypothyroidism symptoms such

as

> constipation and fatigue had disappeared.

>

> Some experts, however, believe that only certain people are apt to develop

> hypothyroidism from eating soy. " For soy to actually cause hypothyroidism,

> you'd have to be bordering on hypothyroidism to begin with, " says

naturopath

> Martin Milner, N.D., president of the Center for Natural Medicine in

> Portland, Ore., and developer of a new treatment for hypothyroidism.

>

> And the amount of soy a person eats may also determine whether this food

> interferes with thyroid function. " I don't think you can get into trouble

if

> you eat a few soyfoods within the bounds of a balanced diet, " as long as

you

> don't have a compromised thyroid system, says Daniel R. Doerge, Ph.D., a

> researcher at the Food and Drug Administration's (FDA) National Center for

> Toxicological Research in Jefferson, Ark., who has isolated and studied

the

> " anti-thyroid " components of soy. " But I see substantial risks from taking

> soy supplements or eating huge amounts of soyfoods for their putative

> disease-preventive value. There is definitely potential for interaction

with

> the thyroid. "

>

> Does Soy Contain Digestion Blockers?

>

> Some researchers consider soy difficult to digest because it inhibits the

> functioning of the pancreatic enzyme called trypsin. The body needs

trypsin

> to properly digest protein. But all legumes have substances called trypsin

> inhibitors that interfere with the work of this enzyme. (Soy is thought to

> have more of these inhibitors than other beans.) When there is less

trypsin,

> more undigested and partially digested protein molecules move through the

> digestive tract.

>

> Mindell acknowledges that mw soybeans do contain trypsin inhibitors. " But

> who's eating raw soybeans? No one, " he says. " Processing and cooking

> deactivates all the trypsin inhibitors. "

>

> Biochemist Irvin E. Liener, Ph.D., professor emeritus at the University of

> Minnesota, reviewed the studies done on trypsin inhibitors and concluded

> that most soyfoods on the market retain 5 to 20 percent of the

> trypsin-inhibitor activity of raw soybeans. His findings appeared in the

> Journal of Nutrition in 1995. In that same issue, researchers Robert L.

> Anderson, Ph.D., and Walter J. Wolf, Ph.D., of the U.S. Department of

> Agriculture's (USDA) National Center for Agricultural Utilization Research

> in Peoria, Ill., reported that fermented soyfoods such as miso and soy

sauce

> generally have lower levels of trypsin inhibitors than soyfoods that are

> processed and cooked but not fermented.

>

> Some researchers point out that eliminating all trypsin inhibitors may not

> be ideal. While high levels of these inhibitors have triggered what appear

> to be premalignant lesions in the pancreases of animals, low levels may

have

> cancer-fighting and cancer-preventing abilities. What's unknown is the

level

> to consume for optimal health. Liener wrote: " If soybean trypsin

inhibitors

> are to be recommended for their anticarcinogenic effects, it becomes

> important to establish the upper limit of exposure at which one can expect

> this preventive effect against cancer but beyond which one runs the risk

of

> incurring adverse effects that have been generally ascribed to the

protease

> inhibitors [which include trypsin inhibitors]. "

>

> Does Soy Prevent the Absorption of Minerals?

>

> The bran or hulls of seeds, found in beans, grains, nuts, and other plant

> foods, contain phytates (or phytic acids). These phytates bind to

essential

> minerals such as calcium, iron, and zinc in the digestive tract and

prevent

> them from being absorbed.

> Soybeans possess a lot of phytates; some researchers say more than other

> beans. Additionally, soy's phytates are so strong that many survive

> phytate-reducing techniques such as cooking. (The phytates in whole grains

> can be deactivated by some soaking or fermenting techniques.)

>

> Fallon and Enig say only long periods of soaking and fermenting--as are

used

> in making miso, natto, shoyu, tamari, and tempeh (but not tofu, soymilk,

> texturized soy protein, or soy protein isolate)--significantly reduce the

> phytate content of soybeans. Anderson and Wolf, in their article in the

> Journal of Nutrition in 1995, also report that tempeh has lower phytate

> levels than unfermented soyfoods. Fallon believes that eating more than 12

g

> of these unfermented foods a day (equal to about a tablespoon) can lead to

a

> shortage of crucial minerals.

>

> But not everyone agrees that phytates are a bad thing. They can move

excess

> minerals out of the body. Stephen Holt, M.D., a gastroenterologist and

> author of The Soy Revolution: The Food of the Next Millennium (M. Evans

and

> Company, 1998), says phytates shield us from dangerously high levels of

> minerals such as iron. And some animal studies have suggested that

phytates

> stop the growth of cancerous tumors. In Earl Mindell's Soy Miracle,

Mindell

> writes that phytates can bind with minerals that may feed tumors.

>

> Does Soy Cause Hormone Havoc?

>

> The plant estrogens (phytoestrogens) found in soy, including isoflavones,

> resemble the natural estrogens in our body. This could be why soy

> consumption promises relief from menopausal symptoms, among other

benefits.

> Yet critics of soy say these isoflavones could cause two specific

problems.

>

> First, some researchers speculate that an isoflavone-rich diet could

> interfere with our ability to reproduce. Scientists have linked

infertility

> to the soy diet of animals such as cheetah and quail. For example,

> researchers at the Children's Hospital Medical Center in Cincinnati, Ohio,

> analyzed the diet of cheetahs living in zoos to figure out why the animals

> experienced infertility. In the journal Gastroenterology in 1987, the

> researchers theorized that the cheetahs' phytoestrogenrich soy diet was

> probably a major factor.

>

> Messina says it's possible but unlikely that soy could affect fertility,

> " but as far as I know there's no problem with reproduction and fertility

in

> the Japanese population or in the American vegetarian population [two

groups

> that eat soy]. "

>

> (According to Soyatech, Inc., a soy research firm in Bar Harbor, Maine,

the

> estimated daily soybean consumption was 9 g per capita in China and 30 g

per

> capita in Japan in 1991. In the United States, the estimated daily

> consumption was 7.5 g per capita in 1991; it rose to 11.2 g in 1996. One

cup

> of cooked soybeans equals 180 g.)

>

> Second, a few researchers question if isoflavones could interfere with the

> hormonal and sexual development of children. Cliff Irvine, D.Sc., a

> reproductive endocrinologist at Lincoln University in Canterbury, New

> Zealand, studied the isoflavone levels in soy infant foods and found that

> the daily recommended intake of soy formula provides 3 mg of isoflavones

per

> kilogram of body weight--a level he says is more than four times the level

> found to change reproductive hormones in women. His findings were

published

> in Proceedings of the Society for Experimental Biology and Medicine in

March

> 1998.

>

> The findings of Irvine and other researchers led some New Zealand

residents

> to lobby for a ban on the sale of soy infant formula except by

prescription.

> The New Zealand government recently decided not to ban the formulas but

> rather to accelerate studies of possible adverse effects.

>

> In America, the infant formula concern has received much less publicity,

but

> Daniel M. Sheehan, Ph.D., a researcher at the FDA's National Center for

> Toxicological Research in Jefferson, Ark., expresses caution. " Infants fed

> soy-based formulas are part of a large, uncontrolled, and basically

> unmonitored human infant experiment, with uncertain risks and benefits, "

he

> says.

>

> " There does exist a theoretical basis for raising concerns, " Messina says

in

> response to the formula charges. But, he adds, soy formula has been used

in

> the United States for at least 30 years, without any apparent harm to

> infants. " To my knowledge there are no letters or case studies published

in

> scientific journals citing problems in soy-fed infants that might be

> attributed to estrogenic effects. Furthermore, many short-term studies

that

> have evaluated infants and children fed soy infant formula have concluded

> that soy formula promotes normal growth and development. "

>

> RELATED ARTICLE: SOY GLOSSARY

>

> ISOFLAVONE a plant-based estrogen (also called phytoestrogen) that

> interrupts the function of hormonal estrogen. Two well-known isoflavones

are

> daidzein and genistein.

>

> MISO a condiment (similar in texture to peanut butter) made with soybeans,

> rice or barley, and salt, and fermented with microorganisms for one to

three

> years. " Quick " miso is pasteurized and aged for only a few days and has a

> less complex taste.

>

> NATTO cooked whole soybeans fermented with microorganisms. With its strong

> flavor, some call natto the Asian answer to blue cheese.

>

> SHOYU traditional Asian soy sauce made from the liquid pressed from miso

> paste. Most soy sauce sold in the United States is unfermented and made

from

> defatted soybean meal (mashed soybeans that have had the fat removed from

> them).

>

> SOYMILK unfermented liquid made from soaked, ground, and cooked whole

> soybeans and water (also available as low-fat soymilk, which may contain

soy

> protein isolate).

>

> SOY PROTEIN ISOLATE an unfermented, highly refined soy protein used to

make

> soy burgers, soy shakes, baked goods, and other foods.

>

> TAMARI another name for traditional soy sauce (or shoyu).

>

> TEMPEH cooked and fermented whole soybean cake. Can be eaten whole or

> crumbled into dishes.

>

> TEXTURIZED SOY PROTEIN unfermented, highly refined meat-textured granules

> made with defatted soy flour (made from soybeans that have been hulled,

> cracked, and heat-treated) that is compressed until the structure of the

> protein changes. Often used to replace ground beef in recipes.

>

> TOFU unfermented soybean curd, made by curdling fresh hot soymilk with a

> coagulant, usually salt. --Clare Horn

>

> RELATED ARTICLE: GENISTEIN AND CANCER: ENEMIES OR ALLIES?

>

> THERE IS MUCH TALK, and hope, in the soy research community that soy

> genistein, one of the isoflavones, can prevent and even cure cancer.

Because

> genistein's molecular structure resembles the hormone estrogen, it is said

> to occupy estrogen-receptor sites on cells and block the growth of

> hormonally induced tumors such as breast cancer tumors. Human and animal

> studies have shown that isoflavones can reduce tumors. There is also

> evidence that genistein might foil the formation of the new blood vessels

> needed to feed a growing tumor, as well as induce " immortal " cancer cells

to

> die.

>

> However, some studies have contradicted these findings. William G.

> Helferich, Ph.D., a researcher at the University of Illinois, found that

> human estrogen-dependent breast cancer cells injected into mice multiply

if

> the mice are fed genistein. His findings were published in Cancer Research

> in September 1998.

>

> " We've seen a lot of good research that suggests that genistein is a

cancer

> preventer, but it is dangerous to people who already have cancer, "

Helferich

> says. " Caution is warranted. "

>

> There is no solid explanation why the research is contradictory. One

theory

> is that the full complement of isoflavones and other components as they

> occur naturally in soyfoods is needed to produce positive results, not

just

> one isolated substance such as genistein.

>

> " The jury is still out as to whether soy or genistein reduces cancer

risk, "

> says Mark Messina, Ph.D., co-author of The Simple Soybean and Your Health

> (Avery, 1994). " The most solid research is that soy lowers cholesterol.

> Almost everything else is speculative, though very encouraging.... My

> opinion is that the isoflavones are safe as long as you take an amount

that

> you could reasonably get from soyfoods. "

>

> --S.E.O.

>

> Sally Eauclaire Osborne is a freelance writer in Santa Fe, N.M.

>

> COPYRIGHT 1999 Weider Publications

>

> COPYRIGHT 2000 Gale Group

>

>

>