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Here’s Part 10 on my series about Iodine, a critical element for your health that most of us are severely depleted in! This week’s input includes my synopsis of some of the information provided by the Linus Pauling Institute at Oregon State University.
___ Iodine is a non-metallic trace element, and it is required by humans for the synthesis of thyroid hormones. Serious Iodine deficiency is an important health problem throughout much of the world, as most of the earth’s Iodine is found in oceans, and Iodine content in the soil varies with region. Seaweeds, sea veggies and ocean fish are the main sources of this CRITICAL element.
The older, land-locked countries or internal areas of large land masses have an old exposed soil surface, so more Iodine has been leached away by erosion and weather. In mountainous regions, (such as the Himalayas, the Andes, the Alps) and in annually-flooded river valleys, (such as the Ganges an Nile), these are among the most severely iodine-deficient areas in the world.
Severe lack of Iodine causes irreversible brain damage.
___ Iodine is an essential component of the thyroid hormones, triiodothyronine (T3) and thyroxine (T4). So, Iodine is essential for normal thyroid function, your metabolism and your ability to control your weight. Your body must also be able to convert T4 into the active form, T3 and some groups of people have problems doing this chemical conversion, so they do not have enough “energy”, and also gain weight.
To meet your body’s demand for thyroid hormones, your thyroid gland traps Iodine from the blood and then incorporates it into thyroid hormones. These are stored and released into the circulation when needed, and travel to all tissues and organ systems.
In target tissues, such as the liver and the brain, T3, the physiologically active thyroid hormone, can bind to thyroid receptors in the nuclei of cells and then regulate gene expression.
In target tissues, T4, the most abundant circulating thyroid hormone, can be converted to T3 by selenium-containing enzymes. So having enough selenium in your diet is also important, as again, most people are selenium-deficient.
This process is how thyroid hormones regulate a number of physiologic activities in your body, including: growth, development, metabolism and reproductive function.
___ The regulation of thyroid function is a complex process that involves the brain (hypothalamus) and pituitary gland, as well as the thyroid gland itself. You can read more about it at: Scientific Iodine Information
But, it is important to know that, in response to decreased blood levels of T4, the pituitary gland increases its output of TSH, and that persistently elevated TSH may lead enlargement of the thyroid gland, also known as goiter.
___ Iodine deficiency is now accepted as the most common cause of preventable brain damage in the world. According to the World Health Organization (WHO), Iodine deficiency disorders (IDD) affect 740 million people throughout the world (that’s about 10% of all humans! But 35% are in jeopardy, due to deficiency of Iodine.). Nearly 50 million people suffer from some degree of IDD-related brain damage.
IDD’s result in: mental retardation, hypothyroidism, goiter and varying degrees of other growth and developmental abnormalities.
Estimates are that over 35% of the world’s population (almost 2 billion people) has insufficient Iodine intake (as measured by urinary iodine excretion below 100 µg/L. Moreover, this analysis estimated that 36.5% of school-age children (6-12 years old) worldwide (285 million total children) has insufficient Iodine intake, and are therefore at risk for brain damage.
Since the 1990’s, major international efforts have produced dramatic improvements in the correction of Iodine deficiency, mainly through the use of iodized salt and iodized vegetable oil in iodine-deficient countries.
Adequate Iodine intake will usually reduce the size of goiters, but the reversibility of the other effects of hypothyroidism depends on an individual’s stage of development. Iodine deficiency has adverse effects in all stages of human development, but is most damaging to the developing brain of fetuses and infants.
In addition to regulating many aspects of growth and development, thyroid hormone is critical for the myelination of your central nervous system, which is most active before and shortly after birth. The myelin sheath covers nerves, the way insulating rubber or plastic does for electrical wires, and it prevents the short-circuiting and disruption of our nerves’ messages. MS, Multiple Sclerosis, is a dis-ease where the nerves have been deprived of their myelin sheath; it is presently increasing in incidence.
The effects of Iodine deficiency by developmental stage
Fetal Iodine deficiency is caused by Iodine deficiency in the mother, and one of the most devastating effects of that deficiency is congenital hypothyroidism, (referred to as cretinism). It results in irreversible mental retardation.
Newborns and infants
Infant mortality is increased in areas of Iodine deficiency. When Iodine deficiency is corrected, there is an increase in childhood survival. Infancy is also a period of rapid brain growth and development and normal brain growth depends on Iodine intake. Deficiency results in impaired intellectual development.
Children and adolescents
Iodine deficiency in children and adolescents is often associated with goiter, and goiter peaks in adolescence. It is more common in girls, as the female thyroid is twice the size of the male’s gland; so girls automatically need more Iodine. Any Iodine deficient child can show lower IQs and a higher incidence of learning disabilities than matched groups from Iodine-sufficient children. A meta-analysis of 18 studies concluded that Iodine deficiency alone lowered mean IQ scores in children by 13.5 points. That’s HUGE!
When I taught school, I had two children in one year’s class who had IQ’s of 70 (as well as others in the same class with IQ’s above 135); it was a teaching night-mare with such disparate needs (but I enjoyed the challenge of teaching the brightest to excel). However, teaching the two at IQ 70 was nearly impossible. It is heart-breaking to know that if it was Iodine related, it could have been eliminated by proper pre-natal and post-natal care for those kids. It’s another reason why I am trying to hammer this lesson home so hard!
Inadequate Iodine intake can still result in goiter and hypothyroidism in adults, during any part of their life. The effects of hypothyroidism are more subtle in adult brains, but research suggests that low-functioning thyroid due to Iodine deficiency results in slower response times and impaired mental function.
Pregnancy and Lactation
Daily Iodine requirements are increased in pregnant and breast-feeding women. And, Iodine deficiency during pregnancy has been associated with increased incidence of miscarriage, stillbirth and birth defects, as well as decreased intelligence for the child.
Moreover, severe Iodine deficiency during pregnancy and lactation affects the fetus, infant and child. Iodine-deficient women who are breast-feeding cannot provide sufficient Iodine to their infants (who are particularly vulnerable to the effects of Iodine deficiency).
A daily prenatal supplement providing the Recommended Dietary Allowance (RDA) of Iodine will help to ensure that pregnant and breast-feeding women consume sufficient Iodine during these critical periods. Check if you can get this! Not all pre-natal vitamins include Iodine and Selenium.
Increased Cancer Risk
Because Iodine deficiency results in increased Iodine trapping by the thyroid, Iodine-deficient individuals of all ages are more susceptible to radiation-induced thyroid cancer from the radio-active Iodine produced from the environment due to human activity (nuclear energy industry and above-ground atomic testing). If you are eating seaweeds, in sufficient quantity, your thyroid will first take up the healthy Iodine 127 isotope, and reject the radio-active, toxic Iodine 131 version, (which will otherwise hog your Iodine receptors in deficiency disease states causing ill health for you and disturbed metabolism).
Selenium deficiency can also exacerbate the effects of Iodine deficiency, as selenium-dependent enzymes are also required for the conversion of thyroxine (T4) to the biologically active thyroid hormone (T3). Additionally, deficiencies of vitamin A or iron may also exacerbate the effects of Iodine deficiency.
Goitrogens – Substances Causing Thyroid Damage
Some foods interfere with Iodine utilization or thyroid hormone production; culprit substances in these foods are called goitrogens.
Cassava, which contains a compound that is metabolized to thiocyanate and that blocks thyroidal uptake of Iodine. Some species of millet and cruciferous vegetables (cabbages, broccoli, cauliflower, Brussels sprouts, mustard greens) also contain goitrogens. Further, the ever-touted soybean isoflavones, genistein and daidzein, have been found to inhibit thyroid hormone synthesis. Most of these goitrogens are not of clinical importance unless they are consumed in large amounts or there is coexisting Iodine deficiency (which exists in most Americans).
Results also indicate that tobacco smoking may be associated with an increased risk of goiter, in iodine-deficient areas.
Individuals at risk of Iodine deficiency
Vegetarian, vegan and meat-eating diets that exclude iodized salt, fish and seaweed have been found to contain very little Iodine.
Urinary Iodine excretion studies suggest that Iodine intakes have also declined in Switzerland, New Zealand, as well as in the U.S. (but recently the US was showing progress, as was Switzerland) . This lack may be happening due to dietary recommendations to eat less salt, so iodized salt intake needs to be replaced with use of ocean fish and / or use of seaweeds and sea veggies.
The Recommended Dietary Allowance (RDA)
Dr. Guy Abraham, MD, world-expert in Iodine says the RDA is set way too low. Read about this in the early part of my series.
The RDA for Iodine was reevaluated by the Food and Nutrition Board (FNB) of the Institute of Medicine in 2001, and it was slightly increased. These are the currents RDA’s.
I apologize for the formatting here. I’ll try to make a table when time permits. Meanwhile, please just persist to read it.
Minimal RDA Intake: double-click on the image to enlarge it
Tolerable Upper Intake Level (UL) for Iodine
Age Group UL (mg/day)
Infants 0-12 months Not possible to establish*
Children 1-3 years 200 mcg/day
Children 4-8 years 300 mcg/day
Children 9-13 years 600 mcg/day
Adolescents 14-18 years 900 mcg/day
Adults 19 years and older 1,100 mcg/day (1.1 mg/day)
*Source of intake should be from mother’s milk, food and formula only.
___ Children with cystic fibrosis may also be more sensitive to the adverse effects of excess Iodine.
___ Individuals with Iodine deficiency, nodular goiter or autoimmune thyroid disease may be sensitive to these intake levels which are considered safe for the general population.
You can get too much Iodine and that is detrimental, just like too little is, but it’s almost impossible to get too much if you get you just get your Iodine from normal portions of food. It is rare for diets of natural foods to supply more than 2,000 mcg of Iodine/day, and most diets supply less than 1,000 mcg of Iodine/day.
The exception is people living in the northern coastal regions of Japan, whose diets contain large amounts of seaweed. They have been found to have Iodine intakes ranging from 50,000 to 80,000 mcg (50-80 mg) of iodine/day, and are healthy! But, they built-up those tolerances over a life-time of use. For you, use just a small serving of seaweed daily or a nori wrap or some seaweed stock or ocean fish a few times a week to get a reasonable quota.
The Iodine in most foods depends on the Iodine soil content. Seafood is rich in Iodine because marine animals can concentrate the Iodine from seawater. Certain types of seaweed (e.g. brown kelps like wakame and kombu) are also very rich in Iodine, for the same reason.
Processed foods may contain slightly higher levels of Iodine due to the use of Iodized salt or food additives, such as calcium iodate and potassium iodate.
Dairy products are relatively good sources of Iodine because Iodine is used to clean cow’s udders before milking and it is commonly added to animal feed in America. But, be aware that in the U.K. and northern Europe, Iodine levels in dairy products tend to be lower in summer when cattle are allowed to graze in pastures with low soil Iodine content.
The table below lists the Iodine content of some foods in micrograms (mcg); 1000 mcg = 1 gram. These values should be considered approximate. See how they affect your Optimal Iodine goal. Double-click on the image to enlarge it.
*A three-ounce serving of meat is about the size of a deck of cards.
** may be greater than 4,500 mcg !!!
I’ll continue next week.
Best to all — Em
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