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From
www.LDAAmerica.org; taken in part
from “Disrupting a Delicate Balance” by Valerie Brown, published in
Environmental Health Perspectives Vol. 111, Number 12, September 2003. For
more information, visit The Healthy Children Project online at
www.healthychildrenproject.org or call 1.888.300.6710.
There are 90
known compounds that can disrupt thyroid hormone production and 12
different ways it can be disrupted. Even a small disruption in a mother’s
hormone level at critical stages in brain development can have devastating
effects. Children of mothers with low circulating thyroid hormone have
been shown to have trouble with motor coordination, balance and other
psychomotor skills. ADHD has been linked to hypothyroidal mothers as well
as a higher than average incidence of difficulties with special relations,
perception, memory and language.
Iodine deficiency is the most common preventable cause of thyroid
disease and developmental disabilities in the world.
Why? THE THYROID GLAND
The thyroid is crucial to human brain development in the womb, in children
and even into one’s twenties. In adults, it plays a role in many functions
of our basic systems. Researchers have recently turned an eye toward the
thyroid to examine it in light of environmental effects.
Just what is this thing called the thyroid anyway?
The thyroid is a small gland that is located near the brain at the base of
the neck. It is part of the endocrine system.
The thyroid requires iodine in order to make its two primary hormones T3
and T4.
Iodine deficiency can result in hypothyroidism (too little hormone).
Symptoms include weight gain, fatigue, dry skin, mood swings and goiter.
Hyperthyroidism (hormone overproduction) may cause anxiety heart
palpitations, insomnia, hair loss, weight loss, and goiter.
…And just what does this gland do?
Thyroid hormone is critical to fetal brain development. It controls
synapse development, neuron formation, and the growth of myelin (the outer
sheath of neurons). It also tells the neurons where they belong once
formed in the brain. In adults, it regulates many systems such as
metabolism, heart rate, blood pressure, and body temperature.
Our brains would not grow without it!
Brain formation begins in the fetus as soon as the first few weeks of
gestation. It is the thyroid hormone, produced by the mother, which
triggers such brain growth. This is true for all vertebrates. In humans,
our own thyroid system is not mature until the third trimester, so it is
necessary for the mother’s hormone to be in constant supply until birth.
In adults, the thyroid works in conjunction with the pituitary gland to
form a self-regulating system, which maintains a constant supply of
hormone in the blood stream.
Even a small disruption in a mother’s hormone level at critical stages in
brain development can have devastating effects. Children of mothers with
low circulating thyroid hormone have been shown to have trouble with motor
coordination, balance and other psychomotor skills. One study shows a 5 to
6 IQ point deficit in these children. ADHD has been linked to
hypothyroidal mothers as well as a higher than average incidence of
difficulties with special relations, perception, memory and language. It
is for these reasons that the thyroid deserves - and has gained –
researchers’ close attention.
Thyroid and the Environment
Research around the thyroid is a difficult endeavor indeed. There are 90
known compounds that can disrupt thyroid hormone production and 12
different ways it can be disrupted. One of the most common types of
offenders are chemicals.
Chemicals affect the thyroid’s delicate balance by inhibiting iodine
intake, or increasing liver metabolism of the hormone, by interrupting to
reception in cells, causing tumors, or suppressing hormone production. It
is important to realize that each family of chemicals comprises many
similar, but not identical, compounds that may or may not cause the same
types of reactions in the thyroid. Many chemicals known to interrupt
reproductive hormones are suspected to harm thyroid production as well.
These are the usual suspects: PCBs, PBDEs (flame retardants), EBDCs
(fungicides), dioxins (paper production etc.) and percholorate (in rocket
fuel).
Research on rats show that environmental chemicals definitely affect the
thyroid.
Like other research on environmental hazards, it is difficult to isolate
one chemical culprit.
Researchers deduce that there are chemicals effecting human thyroid
function by noting iodine deficiencies in iodine-rich areas.
What YOU can
do to prevent thyroid problems and their effects:
Make sure there is a sufficient amount of iodized salt in your daily diet.
Iodine deficiency is one of the four major deficiency diseases in the
world, yet it is the easiest to control. In 1924 salt producers in the
United States cooperated with public health authorities by providing
iodized salt to American consumers significantly limiting iodine
deficiency. Although these deficiencies are now uncommon in Western
societies, the U.S. population has shown a trend of significantly
decreasing iodine intake from 1988–1994. If this trend continues, iodine
deficiency diseases may become more common in the U.S.
Eat an adequate amount of seafood. Foods that are rich sources of iodine
include seafood and kelp.
Include a variety of dairy products in your diet. Dairy products may
contain iodine if the animal giving milk is fed iodine-rich foods.
If you are a strict vegetarian who avoids salt, consider supplementing
your diet with 150 mcg iodine per day. This amount is adequate to prevent
a deficiency and higher amounts may not be necessary
If you are a woman of child-bearing age who anticipates becoming pregnant
anytime in your lifetime, consider having a simple thyroid test.
Thyroid problems affect an estimated 25 million Americans, the vast
majority of them women. Few women, however, are aware of the critical
relationship between the thyroid gland - our master gland of metabolism -
and nearly every aspect of child-bearing – most especially during the
critical period of fetal brain development.
Some doctors recommend routine thyroid testing during a woman’s
pre-pregnancy consult or add it to the routine prenatal diagnostic
testing.
There are also inexpensive at-home thyroid tests which consist of a
laboratory analysis that measures a chemical substance in the blood called
thyroid stimulating hormone (TSH). The test provides you with an accurate,
convenient, and inexpensive way to discover your own TSH level in the
privacy of your own home. One can find information on these tests on the
web.
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