How Iodine Deficiency May Affect Your Child's Brain Function and IQ

Story at-a-glance -

  • Iodine is used by your thyroid gland to help regulate metabolism and development of both skeleton and brain, among other things. Lack of iodine may severely affect your child’s brain function and IQ
  • Iodine deficiency can also cause hypothyroidism, goiter, mental retardation, cretinism, and certain forms of cancer
  • While US RDA for iodine may be insufficient for optimal health and brain function, recent research also casts doubt on high-dose iodine supplementation, as researchers found a dose-dependent relationship between daily intake of 800 mcg of total iodine and higher, with onset of subclinical hypothyroidism
  • Three additional factors that play an important role in the development of proper brain function and high IQ in children are: the animal-based omega-3 fat DHA, vitamin D, avoiding fluoride, and optimizing gut flora

By Dr. Mercola

In this fascinating video, taped at last year's Restorative Medicine Conference in Portland, Oregon, Dr. Jorge Flechas, MD discusses the importance of total body iodine sufficiency, and how lack of iodine might severely affect your child's brain and intellectual prowess. Iodine is an essential trace element required for the synthesis of hormones, and the lack of it can also cause or contribute to the development of:

  • Hypothyroidism
  • Goiter
  • Mental retardation
  • Cretinism (severely stunted physical and mental growth and deafness due to untreated congenital hypothyroidism)
  • Certain forms of cancer

Iodine is used by your thyroid gland to help regulate metabolism and development of both your skeleton and brain, among other things. But how much iodine do you need, really? There's quite a bit of contention on this issue.

Some, like Dr. Flechas insists severe iodine deficiency is rampant, while others claim this is not the case at all, and that taking higher doses of iodine can be harmful. I don't proclaim to have the answer to this question... There's no doubt you need iodine. But it's difficult to say precisely how much.

I suspect the dosages recommended by Dr. Flechas, Dr. Brownstein, and others, may be too high, so I would encourage you to do your own research, and adopt a sensible, middle-of-the-road approach when it comes to iodine.

I also want to clarify the difference between Iodine and Iodide. Iodine is the molecule that is taken up by cells in the body. However, Iodine is a gas and is not very available in food and supplements. Instead, it is the iodide form that is more stable and can be consumed. In the body, Iodide converted into Iodine which is the active form.

Why Is Hypothyroidism More Prevalent in Women than Men?

There is simply no question that optimizing your iodine levels is essential for thyroid health. Hypothyroidism disproportionately affects women at a rate of about 9 to 1 in the US. The reason for this is that the female hormone estrogen inhibits the absorption of iodine.

According to Dr. Flechas, hypothyroidism is associated with up to 80-90 percent free estrogen levels, compared to the normal value of 40-60 percent free estrogen. Hyperthyroidism is associated with only 20 percent free estrogen levels, and low iodine intake can lead to a hyperestrogenic state. In his lecture, Dr. Flechas explains the interplaying dynamics of estrogen, thyroid hormones, and iodine at greater depth, so for more information, please set aside 40 minutes to watch the video above.

Your Body Needs Iodine for More than Just Your Thyroid

Dr. Flechas presents a number of interesting facts about iodine that is not widely known. For example, did you know that thyroid hormones are created not just in your thyroid, but also in a woman's ovaries (thyroid T2), and in the white blood cells of your bone marrow? Furthermore, iodine is not only required for proper function of your thyroid. Other tissues that absorb and use large amounts of iodine include:

Breasts Salivary glands Pancreas Cerebral spinal fluid
Skin Stomach Brain Thymus

Iodine deficiency, or insufficiency, in any of these tissues will lead to dysfunction of that tissue. Hence the following symptoms could provide clues that you're not getting enough iodine in your diet. For example, iodine deficiency in:

  • Salivary glands = inability to produce saliva, producing dry mouth
  • Skin = dry skin, and lack of sweating. Three to four weeks of iodine supplementation will typically reverse this symptom, allowing your body to sweat normally again
  • Brain = reduced alertness, and lowered IQ
  • Muscles = nodules, scar tissue, pain, fibrosis, fibromyalgia
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How Much Iodine Does Your Body Need?

According to Dr. Flechas, researchers have determined that the average dietary intake of iodine for Japanese women is 13.8 milligrams (mg) per day. He recommends 12.5 mg/day, especially for his pregnant patients to optimize their child's intelligence. He shares a couple of success stories in his lecture, where iodine supplementation at higher doses resulted in children with remarkably advanced intelligence.

Hypothyroidism, which is one of the first ailments to develop in response to iodine deficiency, is indeed particularly troublesome during pregnancy. One 1999 study found that thyroid deficiency during pregnancy can lower your child's IQ by about seven points. The researchers noted that for the first 12 weeks of pregnancy, before the unborn child's thyroid becomes active, the mother is the sole source of thyroid hormones. Studies suggest that these hormones play an important role in brain development. Overall, compared with other children, the offspring of thyroid-deficient mothers had impaired school performance and lower scores on tests of attention, language, and visual-motor performance.

But pregnant women aren't the only ones who need to be concerned with the iodine content of their diet. According to Dr. Flechas, your thyroid alone needs about 6 mg of iodine per day; the breasts of a 110-pound woman will need about 5 mg/day (larger women or women with larger breasts need more); and other body tissues, such as your adrenals, thymus, ovaries, hypothalamus, and pituitary gland, need about 2 mg/day.

Here are a few more interesting facts:

  • In total, the human body can hold 1,500 mg of iodine
  • Your thyroid can hold a maximum of 50 mg of iodine
  • 20 percent of the iodine in your body is held in your skin (if your skin is depleted of iodine, you will not be able to sweat)
  • 32 percent of your body's iodine stores are in your muscles (if muscles are depleted, pain and other fibromyalgia symptoms can develop)

Although he makes a compelling argument, I am not yet convinced that such large amounts may be necessary. Dr. Brownstein and others would label this as iodinophobia, but I believe caution may be appropriate here before swallowing mg amounts of iodine on a regular basis. Personally, I am not yet convinced and do not take such high doses in supplemental form.

The US RDA May Be Insufficient for Many

It is important to realize that the current US daily recommended allowance (RDA) for iodine are not in milligram doses but in micrograms:

  • 150 micrograms (mcg) per day for adult men and women
  • 220 mcg for pregnant women
  • 290 mcg for lactating/breastfeeding women

However, this RDA was set with the intention to prevent goiter only. Dr. Flechas makes a compelling argument for it being completely insufficient for overall physical health and prevention of diseases such as thyroid disease, fibromyalgia, and cancer. Iodine actually induces apoptosis, meaning it causes cancer cells to self destruct. Dr. Flechas is adamant that absence of iodine in a cell is what causes cancer, and statistics tend to support this view. In his lecture, he shows the results of a number of NHANES surveys.

For example, between 1971 and 2000, the average iodine levels declined by 50 percent in the US. During that same time, cancers specifically associated with iodine deficiency—such as cancer of the breast, prostate, endometrium, and ovaries—increased.  He also points out that the RDA completely ignores the presence of increasing amounts of goitrogens in the environment. The following halides compete for the same receptors used in your thyroid gland and elsewhere to capture iodine, so if you're exposed to too many of these, your thyroid hormone production can be severely disrupted, resulting in a low thyroid state:

  • Bromide / bromine (Bromide can be found in several forms. Methyl bromide is a pesticide used mainly on strawberries, found predominantly in the California areas. Brominated vegetable oil (BVO) is added to citrus drinks to help suspend the flavoring in the liquid. Potassium bromate is a dough conditioner found in commercial bakery products and some flours)
  • Chlorine
  • Fluoride

Could High-Dose Iodine Be Dangerous?

As I mentioned at the beginning, while Dr. Flechas provides very compelling arguments for using doses as high as 12.5 milligrams (mg) per day, which is a far cry from the RDA of 150 micrograms (mcg), I'm hesitant to make such a recommendation. I think the jury is still out, and we need more research to determine the health effects of too much iodine.

As reported by Reuters at the beginning of this year1, a recently published study has cast some doubts on high-dose iodine supplementation. The study, published December 28, 2011 in the American Journal of Clinical Nutrition2, randomly assigned one of 12 different dosages of iodine (ranging from 0 to 2,000 mcg/day) to healthy adults for four weeks.

When diet was factored in, those taking 400 mcg/day were receiving a total of about 800 mcg of iodine per day.

At doses at and above 400 mcg of supplemented iodine per day, some of the study participants developed subclinical hypothyroidism, which appeared to be dose dependent. At 400 mcg/day, five percent developed subclinical hypothyroidism; at the highest dose—2,000 mcg/day—47 percent of participants were thus affected. Subclinical hypothyroidism refers to a reduction in thyroid hormone levels that is not sufficient to produce obvious symptoms of hypothyroidism (such as fatigue, dry skin, depression or weight gain, just to mention a few common tell-tale signs).

So, these findings suggest it might not be wise to get more than about 800 mcg of iodine per day, and supplementing with as much as 12-13 mg (12,000-13,000 mcg's) could potentially have some adverse health effects.

Four Other Essentials that Promote Higher IQ

While iodine is clearly needed for health brain development and function, it's by no means the only factor that determines your child's mental capacity. The list could get exceedingly long were I to include everything currently known to contribute to decreased or increased IQ, but there are four additional factors that I believe are of particular importance that affects a majority of people:

  1. DHA
  2. Vitamin D
  3. Avoiding fluoride
  4. Optimizing gut flora

DHA—An Essential Fat for Brain Function and IQ

Docosahexaenoic acid, or DHA, is an essential structural component of both your brain and retina. Approximately 60 percent of your brain is composed of fats—25 percent of which is DHA. DHA is also an essential structural ingredient of breast milk, which is believed to be a major reason why breastfed babies consistently score higher on IQ tests than formula-fed babies.

Omega-3 fats such as DHA are considered essential because your body cannot produce it, and must get it from your daily diet. DHA-rich foods include fish, liver, and brain—all of which are no longer consumed in great amounts by most Americans. To compensate for our inherently low omega-3 diet, a high quality animal-based omega-3 supplement is something that I recommend for virtually everyone, especially if you're pregnant. I prefer krill oil to fish oil, as there's compelling evidence demonstrating its superiority.

Most of the DHA needed for brain and nervous system development is transferred from the mother to the fetus during the last trimester. The DHA content in the mother's diet reflects in the amount of DHA passed on to the baby. DHA levels of premature infants are especially low since they miss much of that last trimester. Preemies are also more likely to be bottle-fed, hence missing out on valuable DHA from their mother's breast milk. While you can now find infant formula that contains added DHA, I don't believe it's anywhere near comparable to the DHA found in breast milk.

Studies show that low DHA intake in infancy can lead or contribute to Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD). Low DHA levels have also been linked to increased risk of suicide and dementia.

Why Animal-Based Omega-3?

While there are both plant and animal sources for omega-3 fats, there are differences between them, and when it comes to protecting brain function, you need the animal-based version. There are three important omega-3 fatty acids—ALA, EPA and DHA. DHA is the most important for your brain. EPA is also required by your brain, but in smaller amounts.

Plant-based omega-3 sources like flax, hemp and chia seeds are high in ALA, but low in EPA and DHA. Although ALA is an essential nutrient, the key point to remember is that the conversion of ALA to the far more essential EPA and DHA is typically quite inhibited by impaired delta 6 desaturase, an enzyme necessary for you to convert the ALA into the longer chain EPA and DHA. Because of this, it is important to include animal-based sources of omega-3 fats, such as krill oil, in your diet.

Vitamin D Deficiency May Be a Primary Culprit in Skyrocketing Autism Rates

In more recent years, rampant vitamin D deficiency has been linked to a proportionate jump in autism. While the connection may not be obvious, it's important to realize that vitamin D receptors appears in a wide variety of brain tissue during early fetal development, and activated vitamin D receptors increase nerve growth in your brain. Researchers have also located metabolic pathways for vitamin D in the hippocampus and cerebellum of the brain, areas that are involved in planning, processing of information, and the formation of new memories.

The National Institutes of Mental Health recently concluded that it is vital that the mother get enough vitamin D while pregnant in order for the baby's brain to develop properly. The child must also get enough vitamin D after birth for "normal" brain functioning. Appropriate sun exposure would take care of these issues, as the sun is irreplaceable when it comes to the body's ability to produce adequate amounts of vitamin D.

Vitamin D deficiency is also associated with depression. In 2006, scientists evaluated the effects of vitamin D on the mental health of 80 elderly patients and found those with the lowest levels of vitamin D were 11 times more prone to be depressed than those who received healthy doses. More recently, researchers found that intake of more than 400 IU of vitamin D from food sources was associated with a 20 percent lower risk of depressive symptoms compared with intake of less than 100 IU. This was a significant benefit from a very small amount of vitamin D -- as 400 IU is far too low to benefit most people.

It now appears as though most adults need about 8,000 IU's of vitamin D a day in order to get their serum levels above 40 ng/ml, which is the lowest they should be. Ideally your serum levels should be between 50-70 ng/ml, and up to 100 ng/ml to treat cancer and heart disease. However, it's important to realize that there's no magic dosage when it comes to vitamin D. What's important is your serum level, so you need to get your vitamin D levels tested to make sure you're staying within the optimal and therapeutic ranges as indicated below.

vitamin d levels

Fluoride Found to Harm Brain Function and Lower IQ in Children

Fluoride is known to interfere with basic functions of nerve cells in your brain3, and numerous animal and human studies demonstrate the damage fluoride inflicts on your brain, including your pineal gland. Shockingly—considering the fact that 70 percent of the US is still fluoridating their water supplies—there are more than 25 human studies and 100 animal studies4 linking fluoride to brain damage and reduced IQ in children. This includes such effects as:

Reduction in nicotinic acetylcholine receptors Damage to the hippocampus Formation of beta-amyloid plaques (the classic brain abnormality in Alzheimer's disease)
Reduction in lipid content Damage to the purkinje cells Exacerbation of lesions induced by iodine deficiency
Impaired antioxidant defense systems Increased uptake of aluminum Accumulation of fluoride in the pineal gland

Fluoride can also increase manganese absorption, compounding problems since manganese in drinking water has also been linked to lower IQ in children.

One of the most recent studies into the effects of water fluoridation on intellectual performance, published in December 20105, found that about 28 percent of children in the low-fluoride study area scored as "bright, normal or higher intelligence" compared to only 8 percent in the high-fluoride area. Further, 15 percent of children in the high-fluoride city had signs of mental retardation, compared with only 6 percent in the low-fluoride city. Most alarmingly, some of these brain-damaging effects have been observed even at low levels of exposure, such as 1 part per million (ppm) of fluoride in water, which is right around the levels used in US water fluoridation programs, which range from 0.7-1.2 ppm.

Optimizing Gut Flora Strengthens Natural Detoxification Pathways

The presence of, and continual exposure to, toxins is another important factor that can have profound influence on your child's IQ—both in utero and after birth. According to Dr. Natasha Campbell-McBride, neurological problems such as autism and learning disorders are caused by toxic overload, stemming from abnormal gut flora.

Children use all of their sensory organs to collect information from their environment, which is then passed to the brain for processing. This is a fundamental part of learning. However, in children with Gut and Psychology Syndrome (GAPS), the toxicity flowing from their gut throughout their bodies and into their brains, clogs the brain with toxicity, preventing it from performing its normal function and process sensory information. GAPS may manifest as a conglomerate of symptoms that can fit the diagnosis of autism, attention deficit hyperactivity disorder (ADHD), attention deficit disorder (ADD) without hyperactivity, dyslexia, dyspraxia, or obsessive-compulsive disorder, just to name a few possibilities.

The treatment she developed is called the GAPS Nutritional Program, which covers both diet and detoxification. Fermented foods are a staple of the GAPS diet. The beneficial bacteria in these foods are very potent detoxifiers, capable of drawing a wide range of toxins and heavy metals out of your body. According to Dr. McBride, the GAPS Nutritional Protocol restores the natural detoxification system in about 90 percent of people, and the fermented/cultured foods are instrumental in this self-healing process.

"The cell wall [of the bacteria] have chelators; molecules that grab hold of mercury, lead, aluminum, arsenate, and anything else toxic," Dr. McBride explains. "They hold them until they're removed through stool."

You don't need to consume huge amounts. About a quarter to a half a cup of fermented vegetables, or cultured food such as raw yoghurt, per day, is sufficient. The key is variety. The greater the variety of fermented and cultured foods you include in your diet, the better, as each food will inoculate your gut with a variety of different microorganisms.

Planning for a Bright and Healthy Baby...

As you can see, there are many factors contributing to making a healthy, happy, and bright baby—and there are many more that I did not expound on in this article, such as:

  • Phosphatidylserine (PS), a phospholipid that is an essential part of the membranes that surround all your body's cells. PS enables cells to move nutrients into and cellular waste out of each living cell in your body. Abundant in your brain and in the membranes of your brain cells, PS is important for brain functions such as memory, judgment, and reasoning. Cow brain, mackerel, herring, and organ meats are some of the foods that contain higher levels of PS
  • GPC (Glycerophosphocholine), the bioactive form of choline. Unlike the other forms of choline, GPC is the form that has substantial clinical evidence behind it for its direct effect on healthy brain functions. It occurs naturally in limited quantities in eggs, milk, nuts, fish, certain vegetables, organ meats, and human breast milk
  • Magnesium is another important element needed for optimal brain function and IQ. Stress has been shown to have a detrimental impact on magnesium levels, which in turn can result in lower IQ levels in school-age children, according to some research.6

Fortunately, most of these factors are largely, or entirely, within your control. For even more healthy pregnancy tips, please see this previous article.