Fwd: Do Soy Foods Negatively Affect Your Thyroid?

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Neil Jensen

Wed, 24 Dec 2003 22:32:14 -0700

Do Soy Foods Negatively Affect Your Thyroid?

 

Latest Update from Thyroid-Info: December 24, 2003

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Do Soy Foods Negatively Affect Your Thyroid?

A Look at the Downsides of Soy

 

by Mary Shomon

 

It seems that there's isn't a newspaper, magazine or news program that hasn't

recently featured a story on the amazing health benefits of soy food products

and soy/isoflavone supplements. Soy is promoted as a healthy alternative to

estrogen replacement for some women, as a possibly way to reduce the risk of

breast cancer, as a way to minimize menopause symptoms, and as a healthier,

low-fat protein alternative for meats and poultry. But what all the positive

stories fail to mention is that there is a very real -- but very overlooked --

downside to the heavy or long-term use of soy products.

 

Soy products increase the risk of thyroid disease. And this danger is

particularly great for infants on soy formula.

 

This is not information that the powerful and profitable U.S. soy industry wants

you to know. The sale of soy products is big business, and the increasing demand

for soy protein products, soy powders and soy isoflavone supplements is making

that an even more profitable business than ever before.

 

In researching my book, Living Well With Hypothyroidism, which covers the issue

of soy products and the thyroid in great depth, I talked to Dr. Mike

Fitzpatrick, an environmental scientist and phytoestrogen researcher who has

conducted in-depth studies on soy, particularly the use of soy formulas. Dr.

Fitzpatrick makes it clear that soy products can have a detrimental affect on

both adults and infants. In particular, he firmly believe that soy formula

manufacturers should remove the isoflavones -- that part of the soy products

that act as anti-thyroid agents -- from their products.

 

Researchers have identified that the isoflavones act as potent anti-thyroid

agents, and are capable of suppressing thyroid function, and causing or

worsening hypothyroidism. Soy is a phytoestrogen, and therefore acts in the body

much like a hormone, so it's no surprise that it interacts with the delicate

balance of the thyroid's hormonal systems. High consumption of soy products are

also proven to cause goiter, (Anti-thyroid isoflavones from soybean: isolation,

characterization, and mechanisms of action,Divi RL; Chang HC; Doerge DR,

National Center for Toxicological Research, Jefferson, AR 72079, USA, Biochem

Pharmacol, 1997 Nov, 54:10, 1087-96)

 

Note: The best source of information on soy and its negative impact on health

can be found at the Soy Online Service, and in particular, its page on

phytoestrogenic effects of soy, and impact on the thyroid.

 

Isoflavones belong to the flavonoid or bioflavonoid family of chemicals, and are

considered endocrine disrupters -- plants or other products that act as

hormones, disrupting the endocrine system, and in some cases, this disruption

involves acting as an anti-thyroid agent. (The grain millet, for example,

contains high levels of flavonoids, and is commonly known as problematic for

thyroid function). Flavonoids inhibit thyroid peroxidase (TPO), which disturbs

proper thyroid function.

 

The March 1999 issue of Natural Health magazine has a feature on soy that quotes

Daniel R. Doerge, Ph.D., a researcher at the Food and Drug Aministration's

National Center for Toxicological Research. Dr. Doerge has researched soy's

anti-thyroid properties, and has said " ...I see substantial risks from taking

soy supplements or eating huge amounts of soy foods for their putative disease

preventive value. There is definitely potential for interaction with the

thyroid. "

 

One UK study of premenopausal women gave 60 grams of soy protein per day for one

month. This was found to disrupt the menstrual cycle, with the effects of the

isoflavones continuing for a full three months after stopping the soy in the

diet. Isoflavones are also known to modify fertility and change sex hormone

status. Isoflavones have been shown to have serious health effects -- including

infertility, thyroid disease or liver disease -- on a number of mammals.

 

Dr. Fitzpatrick believes that people with hypothyroidism should avoid soy

products, because, " any inhibition of TPO will clearly work against anyone

trying to correct an hypothyroid state. " In addition, he believes that the

current promotion of soy as a health food will result in an increase in thyroid

disorders.

 

The Dangers of Soy Formulas

 

Since the late 1950's, it has been known that soy formulas contain anti-thyroid

agents. Infants on soy formula are particularly vulnerable to developing

autoimmune thyroid disease when exposed to high exposure of isoflavones over

time. ( Breast and soy-formula feedings in early infancy and the prevalence of

autoimmune thyroid disease in children. Fort P; Moses N; Fasano M; Goldberg T;

Lifshitz F Department of Pediatrics, North Shore University Hospital-Cornell

University Medical College, Manhasset, New York 11030. J Am Coll Nutr, 1990 Apr,

9:2, 164-7) This study found that the frequency of feedings with soy-based milk

formulas in early life was noticeably higher in children with autoimmune thyroid

disease, and thyroid problems were almost triple in those soy formula-fed

children compared to their siblings and healthy unrelated children. Dr.

Fitzpatrick even believes that long-term feeding with soy formulas inhibits TPO

to such an extent that long-term elevated TSH levels can also

raise the risk of thyroid cancer.

 

Not much is being done in the U.S. to make parents aware of the thyroid-related

dangers of soy formulas, or to alert the public that heavy soy consumption may

be a danger to thyroid function. Other countries, however, are far ahead of the

U.S. In July of 1996, the British Department of Health issued a warning that the

phytoestrogens found in soy-based infant formulas could adversely affect infant

health. The warning was clear, indicating that soy formula should only be given

to babies on the advice of a health professional. They advised that babies who

cannot be breastfed or who have allergies to other formulas be given

alternatives to soy-based formulas.

 

Why more information is not available about these concerns is probably a

function of the tremendous strength of the large agricultural companies that

dominate America's soy market. One thing is clear, however. At the same time

that health experts, and nearly every radio and television health program in the

nation touts soy as the miracle health food of the new millenium, the United

States pediatric and medical community needs to get more on top of this issue,

and begin to counsel their patients regarding the serious impact use of soy

products can have on thyroid function.

 

How Much Soy is Safe?

 

According to the Soy Online Service, for infants, any soy is too much. For

adults, just 30 mg of soy isoflavones per day is the amount found to have a

negative impact on thyroid function. This amount of soy isoflavones is found in

just 5-8 ounces of soy milk, or 1.5 ounces of miso. For more information on how

much soy is too much, see the Soy Online Service guidance page.

 

The USDA has launched a website that is promoting the health benefits of use of

soy and soy foods. The USDA site lists the isoflavone content of a total of 128

foods, including foods such as vegetarian hot dogs soybeans, chickpeas and tofu.

This can help you in deciding how much soy to include in your diet

--

Neil Jensen: neil

The WWW VL: Sumeria http://www.sumeria.net/

" ...but I know I have to beat time

when I learn music. " -- Alice

 

 

 

 

 

 

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