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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.
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
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