We're sick of hearing
that there are no harmful effects of phytoestrogens.
Phytoestrogens disrupt thyroid function.
(Read the British Food Standards Agencies Committee on Toxicity
Report Here)
Theodore Kay of the Kyoto University
Faculty of Medicine noted in 1988 that 'thyroid enlargement in rats
and humans, especially children and women, fed with soybeans has
been known for half a century'.
In fact, thyroid problems associated
with soy were also well known to bird-breeders,
which is how Soy Online Service first became aware of the goitrogenicity
of soy.
Well known, but that fact seemed
to escape manufacturers of the first commercially available soy
formulas. Those formulas were known to cause in goitre
in infants and one can only wonder how many other infants were
left hypothyroid or suffering from permanent thyroid damage by soy
formulas.
The iodine levels in soy formulas
were increased and instances of goitre in infants fed these products
ceased. However, there appears to have been no attempt to
isolate or remove the goitrogenic properties from soy formulas.
This is of grave concern because, although elevated iodine
levels would have helped to nullify the effects of the goitrogens,
the goitrogens would still have been actively suppressing thyroid
function in infants. Hence millions of babies (particularly
in the United States where soy formula feeding is most common) have
needlessly been exposed to goitrogenic agents; Soy Online Service
believe that infants fed soy formulas unnecessarily risk abnormal
thyroid function and a greater risk of thyroid disease in later
life.
So just what are these goitrogenic
agents? In 1997 research from the FDA's National Center for
Toxicological Research (NCTR) showed that the darling of the soy
industry, the isoflavone genistein, was a potent
inhibitor of Thyroid Peroxidase (TPO); in fact genistein is
a more powerful inhibitor of TPO than common anti-thyroid drugs!
If genistein could inhibit TPO in vitro, it follows that it could
result in an elevation of Thyroid Stimulating Hormone (TSH), and
a subsequent decrease in thyroxine (T3) in vitro; in other words
consumption of the soy isoflavone genistein might result in hypothyroidism
and goitre.
Recent research leaves little doubt
that dietary isoflavones in soy have a profound effect on thyroid
function in humans. A study by Japanese
researchers concluded that intake of soy by healthy adults for
a long duration caused enlargement of the thyroid and suppressed
thyroid function. These researchers studied the effects of feeding
30 g of soybeans per day on thyroid function and found that after
one month there was a significant increase in thyroid stimulating
hormone (TSH) levels in a group of 20 adults (group I) but no change
in thyroxine levels.
Diffuse goitre and hypothyroidism
appeared in some of these subjects and about half of another group
of 17 adults (group II) that took soybeans for 3 months. This group
also had increased TSH levels, especially in older subjects, but
once again there was no significant change in plasma thyroxine.
After three months of soy intake other relevant symptoms included
constipation (in 53% of subjects), fatigue (in 53% of subjects),
lethargy (in 41% of subjects). It should be noted that iodine intake
(via seaweed) was normal in all subjects.
The goitre was a diffuse goitre (degrees
I and II enlargement) and occurred in 3 of group 1 and 8 (47%) of
group 2. One subject in group 1 developed sub-acute thyroiditis.
Two of the 11 subjects with goitre showed no reduction in goitre
size one month after cessation of soy but goitre size was reduced
in the other 9 subjects. The two subjects received thyroxine treatment
and their goiters reduced in size after two and six months respectively.
The combination of a moderately elevated
TSH with a normal free thyroxine defines subclinical hypothyroidism,
a condition which may evolve towards overt hypothyroidism especially
in persons with anti-thyroid antibodies. The condition is defined
as the state in which a reduction in thyroid hormone secretion is
compensated for by an increased TSH production to order maintain
a clinically euthyroid status. Subclinical hypothyroidism is of
increasing importance and its prevalence appears to be growing such
that studies to define both its evolution and strategies for its
management are warranted. Thyroid experts have noted that dietary
factors may well play a major role in the development of this condition
since high goitrogen intake can increase TSH secretion.
We have already noted that isoflavones
bioaccumulate
in infants fed soy formulas. Hence, there is strong evidence
from both in vitro and in vivo studies that persistent
TPO inhibition will occur in infants subjected to soy formulas long-term
(for more than three months). The work of Ishizuki indicates that
this persistent exposure to the anti-thyroid agents in soy will
result in variable and elevated levels of TSH, even if iodine levels
are sufficient. There is a bounty of evidence showing that scenarios
such as this can result in various thyroid diseases in humans.
Soy Online Service believe that it
is utterly irresponsible for soy formula manufacturers to continue
to place infants at risk of thyroid damage by refusing to remove
isoflavones from their products. Soy Online Service also believe
that it is totally irresponsible and a sign of moral corruptness
to promote anti-cancer benefits of soy without any inference that
there may be other health risks (for example to the thyroid).
There is an epidemic
of thyroid disease in the United States. If you were fed
a soy formula and suffer from a thyroid disorder, or have any reason
to believe that soy may have caused you to develop a thyroid disorder,
please contact us.
More information on developmental
disorders caused by thyroid dysfunction is available here.
Soy
formula complicates management of congenital hypothyroidism.
Infants fed soy formula had prolonged increase of TSH when compared
to infants fed non-soy formula. These infants need close monitoring
of free thyroxine and TSH measurements, and they may need increased
levothyroxine doses to achieve normal thyroid function tests.
Actual
levels of soy phytoestrogens in children correlate with thyroid
laboratory parameters.
Even small differences in soy phytoestrogen
intake may influence thyroid function, which could be important
when iodine intake is insufficient
Soy
formulas and the effects of isoflavones on the thyroid, by Dr.
Mike Fitzpatrick (2000), published in the NZ Medical Journal Issue
113.
Leading thyroid expert, Mary Shomon
writes of dangers to the thyroid. Read more here Soy's
Thyroid Dangers: A Look at the Dangers of Soy to the Health of Your
Thyroid by Mary J. Shomon
Soy formula complicates management of congenital
hypothyroidism
S C Conrad, H Chiu and B L Silverman. Archives of Disease
in Childhood 2004;89:37-40
There was a significant
difference between the two groups in the following areas: time
to TSH normalisation, first TSH on treatment, percentage with
increased TSH at 4 months of age, percentage with increased TSH
throughout the first year of life, and in the overall trend of
TSH at each visit.
Conclusions: Infants fed
soy formula had prolonged increase of TSH when compared to infants
fed non-soy formula. These infants need close monitoring of free
thyroxine and TSH measurements, and they may need increased levothyroxine
doses to achieve normal thyroid function tests.
Full
Abstract Here
Dietary genistein inactivates
rat thyroid peroxidase in vivo without an apparent hypothyroid
effect.
Chang HC, Doerge DR. Toxicol Appl Pharmacol. 2000 Nov 1;168(3):244-52.
...substantial amounts
of TPO activity are lost concomitant to soy isoflavone consumption
by normal rats, the remaining enzymatic activity is sufficient
to maintain thyroid homeostasis in the absence of additional perturbations.I
Full Abstract Here
f the thyroid function of rats
can be compared to that of humans, then the reduction of thyroid
function (thyroid peroxidase) by the soy estrogen of up to 80%
could be highly dangerous. These researchers suggest that the
thyroid of rats can function even though 80% of its capacity is
inhibited if there is no other perturbing factor. In other research
this same FDA laboratory (link to "Anti-thyroid Isoflavones
From Soybean") has stated that any substance that inhibits
TPO is by definition a potential carcinogen in thyroid tissue
(Abstract Here).
The New York Daily News has a penetrating
article on the thyroid damage that soy can cause. Read more
Here
Do Soy Foods Negatively Affect Your Thyroid? A look at the Downside
of Soy by Mary Shomon.
This website
http://www.goddessdiet.com/Reports/thyroid.htm has the research
articles women need to present to their doctors in order to get
the right laboratory values, and antibody studies done.
Is
Soy Bad For You? New research links the 'health' food
to thyroid disorders.
"Although safety testing of
natural products, including soy products, is not required, the possibility
that widely consumed soy products may cause harm in the human population
via either or both estrogenic and goitrogenic activities is of concern."
reports Drs Doerge and Sheehan in a recent article in the journal
Environmental Health Perspectives.
Full Abstract Here.
Useful advice for sufferers of thyroid
abnormalities is at Krispin Sullivan's website
http://www.krispin.com/thyroid.html
For more information on thyroid disease,
visit Mary Shoman's thyroid
website and also read the following article by Robert
J. Thiel published on www.healthresearch.com/thyroid.htm.
Also read Jennifer
Phillips article on Thyroid Hormone Disorders.
"From 'Hippocrates Health'
the popular Australian health resource website: http://www.doctorsaredangerous.com/thyroid.htm
Read the testimonies
of people who have suffered thyroid problems because of soy/isoflavone
supplements and the shocking results of Larrian
Gillespie's "self as a guinea-pig" experiment.
Also read our Big
Ugly Bull Award to the FDA-CFSAN for endorsing the consumption
of thyroid disease causing compounds.
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