Thyroid Deficiency Linked to Iodine Deficiency and Fluoridated Water

Written by Dr. Joseph Mercola

You can skip this video in  seconds
Skip Ad

Visit the Mercola Video Library

Story at-a-glance -

  • People who have moderate-to-severe iodine deficiencies and higher fluoride levels may be at an increased risk for underactive thyroid gland activity
  • Pregnant women living in communities with fluoridated drinking water have two times the amount of fluoride in their urine as women living in nonfluoridated communities
  • Research has previously revealed that women with higher levels of fluoride in their urine during pregnancy were more likely to have children with lower intelligence
  • Higher levels of fluoride exposure during pregnancy were associated with higher measures of ADHD, including more symptoms of inattention, in the children at ages 6 to 12 years

More than 66 percent of the U.S. population drinks water with added fluoride,1 despite the fact that studies continue to question its safety and usefulness for its stated purpose: preventing cavities. A number of countries — including Germany, Sweden, Japan, the Netherlands, Finland and Israel — have already stopped this hazardous practice, but many Americans are still at risk.

In Canada, nearly 39 percent of the population also receives fluoridated drinking water (compared with only about 3 percent of Europeans).2 It's been known for years that fluoridated water consumption is linked to thyroid dysfunction and behavioral problems like attention deficit hyperactivity disorder (ADHD), and two new studies have added to the already apparent associations.

Exposure to Fluoridated Water May Disrupt Thyroid Functioning

Your thyroid gland, located in the front of your neck, influences almost every cell in your body. Thyroid hormones regulate your metabolism and are required for growth and development in children and nearly every physiological process in your body.

When your thyroid levels are unbalanced, it can lead to a cascade of problems throughout your body. In hypothyroidism, the most common thyroid disorder, your thyroid gland activity is suppressed.

Also known as underactive thyroid, many with this condition are unaware they have it, and another 4 to 10 percent of the U.S. population may suffer from subclinical hypothyroidism that is missed by testing yet associated with miscarriage, preterm birth and altered growth and neurodevelopment in babies.

Even moderately imbalanced thyroid levels may be associated with increased risk of metabolic syndrome, researchers noted in the journal Environment International, which is why "studying factors that contribute to low thyroid function, even at the subclinical level, is of high public health importance."3

Notably, subclinical hypothyroidism is diagnosed by high serum thyroid-stimulating hormone (TSH) concentrations, and "fluoride in drinking water, even at levels as low as 0.3–0.5 mg/L, have predicted elevated TSH concentrations," the researchers added. "Higher water fluoride concentrations have also predicted an increased likelihood of a hypothyroidism diagnosis among adults."4

The latest study, which involved data from nearly 7 million Canadian adults not taking any thyroid-related medication, found that higher fluoride levels were not associated with higher TSH levels in the general population; however, when iodine status was accounted for, the results shifted.

Iodine Deficiency May Heighten the Risks of Fluoridated Water

Your body uses iodine across several organ systems, but it is most commonly known to synthesize thyroid hormones. Clinically low levels of iodine are associated with visible symptoms, such as a goiter (swelling of the thyroid gland), hypothyroidism or pregnancy-related problems. However, subclinical iodine deficiency can also interfere with your thyroid function.

Meanwhile, the Canadian study revealed that adults in Canada who have moderate-to-severe iodine deficiencies and higher fluoride levels tend to have higher TSH levels, which indicates they may be at an increased risk for underactive thyroid gland activity.5

It's a startling finding, considering nearly 2 billion people worldwide don't get enough iodine in their diet.6 As the researchers of the featured study noted, this means that those with iodine deficiency may be at an even greater increased risk from drinking fluoridated water:7

"Iodine deficiency can contribute to decreased thyroid hormone production and exacerbate the thyroid-disrupting effects of certain chemicals, as well as fluoride …

Fluoride exposures of 0.05 to 0.13 mg/kg/day have been associated with adverse thyroid effects among iodine sufficient people, while lower fluoride exposures of 0.01 to 0.03 mg/kg/day have been associated with these effects among iodine deficient people."

The effects were so worrying that lead study author Ashley Malin, a researcher at the department of environmental medicine and public health, Icahn School of Medicine at Mount Sinai, told Environmental Health News:8

"I have grave concerns about the health effects of fluoride exposure … And not just from my study but the other studies that have come out in recent years … We're talking about potentially [more than] a million people at risk of an underactive thyroid due to fluoride exposure."

In 2015, for instance, British researchers warned that 15,000 people may be afflicted with hypothyroidism in the U.K. as a result of drinking fluoridated water.9 In areas where fluoride levels in the water registered above 0.3 mg/l, the risk of having a high rate of hypothyroidism was 37 percent greater compared to areas that do not fluoridate.

Pregnant Women Drinking Fluoridated Water Have Higher Fluoride Levels

Fluoride exposure can occur from multiple sources, ranging from tea and processed foods to dental products, pharmaceuticals and fluoride-containing pesticides. However, research continues to show that drinking water remains a primary route of exposure, including in pregnant women.

In a study of more than 1,500 pregnant women living in Canada, those living in communities with fluoridated drinking water have two times the amount of fluoride in their urine as women living in nonfluoridated communities.10

"Research is urgently needed to determine whether prenatal exposure to fluoride contributes to neurodevelopmental outcomes in the offspring of these women," researchers explained.11 In fact, research has previously revealed that women with higher levels of fluoride in their urine during pregnancy were more likely to have children with lower intelligence.

Specifically, each 0.5 milligram per liter increase in pregnant women's fluoride levels was associated with a reduction of 3.15 and 2.5 points on the children's General Cognitive Index (GCI) of the McCarthy Scales of Children's Abilities and Wechsler Abbreviated Scale of Intelligence (WASI) scores, respectively.

Lead researcher Dr. Howard Hu, of the Dalla Lana School of Public Health at the University of Toronto in Canada, said in a news release:12

"Our study shows that the growing fetal nervous system may be adversely affected by higher levels of fluoride exposure. It also suggests that the prenatal nervous system may be more sensitive to fluoride compared to that of school-aged children."

The findings were groundbreaking, as the study, which spanned 12 years and received funding from the U.S. National Institutes of Health (NIH), was one of the first and largest studies looking into this topic.

Prenatal Fluoride Exposure Is Linked to ADHD

The Canadian study on pregnant women living in fluoridated communities revealed levels of fluoride similar to those found in a study of pregnant women living in Mexico City, where the chemical is added to table salt. The same Mexican sample population has now been featured in another study, linking fluoride exposure to ADHD.13

The study, which involved more than 200 mother-children pairs, found that higher levels of fluoride exposure during pregnancy were associated with higher measures of ADHD, including more symptoms of inattention, in the children at ages 6 to 12 years. "[The f]indings are consistent with the growing body of evidence suggesting neurotoxicity of early-life exposure to fluoride," researchers explained.14

It's also possible that fluoride may contribute to or exacerbate behavioral problems such as ADHD by way of pineal gland calcification. Despite its diminutive size, your pineal gland tends to accumulate significant amounts of fluoride, which eventually causes it to calcify.

Besides ADHD-like symptoms, pineal calcification may also play a role in Alzheimer's and bipolar disease. According to Frank Granett, director of clinical pharmacy operations at Behavioral Center of Michigan Psychiatric Hospital:15

"Located deep within the brain below the corpus callosum, which is the circuit connector for the right and left brain hemispheres, the pineal gland is responsible for the secretion of melatonin, the human body's biological time-clock hormone regulating normal sleep patterns.

More importantly, the pineal gland plays a critical role in the enzyme pathway for the production of brain neurotransmitters including serotonin and norepinephrine. Additionally, the body's antioxidant defense system is optimized by healthy pineal tissue, which helps eliminate free-radical toxin accumulation in the body."

A review in Lancet Neurology also classified fluoride as one of only 11 chemicals "known to cause developmental neurotoxicity in human beings,"16 alongside other known neurotoxins such as lead, methylmercury, arsenic and toluene. Among the proposed mechanisms of harm, studies have shown fluoride can:17

Interfere with basic functions of nerve cells in the brain

Reduce nicotinic acetylcholine receptors

Reduce lipid content in the brain

Damage the pineal gland through fluoride accumulation

Impair antioxidant defense systems

Damage the hippocampus

Damage Purkinje cells

Increase uptake of aluminum, which has neurotoxic effects

Encourage formation of beta-amyloid plaques (the classic brain abnormality in Alzheimer's disease)

Exacerbate lesions induced by iodine deficiency

Increase manganese absorption, which has also been linked lower IQ in children

Impair thyroid function, which can also affect brain development

Can Fluoride Be Removed From Drinking Water?

Effective 2015, the level of fluoride in U.S. drinking water was reduced to 0.7 mg/L from a previously recommended range of between 0.7 and 1.2 mg/L. If you live in the U.S. and want to know fluoride levels in your water, the Environmental Working Group's (EWG) Tap Water Database can help.18 This is important for everyone, but pregnant women and households mixing formula for babies should take extra care to consume fluoride-free water. EWG notes:

"Even fluoride levels of 0.7 ppm, the amount of fluoride in drinking water recommended by the U.S. Public Health Service, can result in too much fluoride for bottle-fed babies.

EWG recommends that caregivers mix baby formula with fluoride-free water. The National Toxicology Program is investigating the potential for low doses of fluoride to alter thyroid function and childhood brain development."19

Unfortunately, fluoride is a very small molecule, making it tremendously difficult to filter out once added to your water supply. Any simple countertop carbon filter, like Brita, will not remove it.

If you have a house water carbon filtration system that has a large volume of carbon, then it may reduce the fluoride as fluoride removal is in direct proportion to the amount of fluoride and the time it's in contact with the media. It's just not going to get it all. Among the more effective filtering systems for fluoride removal are:

  • Reverse osmosis (RO). The drawback is that it will remove many valuable minerals and trace elements as well. RO systems also need frequent cleaning to avoid bacterial growth. So, use a tankless RO system with a compressor
  • Water distillation, which, like RO, gets everything out, including beneficial minerals. You then need to restructure the water
  • Bone char filters and biochar with activated charcoal

The simplest, most effective, most cost-effective strategy is to not put fluoride in the water to begin with.

Help End the Practice of Fluoridation

There's no doubt about it: Fluoride should not be ingested. Even scientists from the EPA's National Health and Environmental Effects Research Laboratory have classified fluoride as a "chemical having substantial evidence of developmental neurotoxicity."

Furthermore, according to the CDC, 41 percent of American adolescents now have dental fluorosis — unattractive discoloration and mottling of the teeth that indicate overexposure to fluoride. Clearly, children are being overexposed, and their health and development put in jeopardy. Why? The only real solution is to stop the archaic practice of water fluoridation in the first place.

Fortunately, the Fluoride Action Network has a game plan to END water fluoridation worldwide. Clean pure water is a prerequisite to optimal health. Industrial chemicals, drugs, and other toxic additives really have no place in our water supplies. So, please, protect your drinking water and support the fluoride-free movement by making a tax-deductible donation to the Fluoride Action Network today.

Internet Resources Where You Can Learn More

I encourage you to visit the website of the Fluoride Action Network (FAN) and visit the links below:

Together, Let's Help FAN Get the Funding They Deserve

In my opinion, there are very few NGOs that are as effective and efficient as FAN. Its small team has led the charge to end fluoridation and will continue to do so with our help! Please make a donation today to help FAN end the absurdity of fluoridation.