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Thyroid dysfunction

“Iodine is the key that turns on the thyroid’s energy engine, but fluoride intake causes thyroid cells to pick up fluoride instead, causing the thyroid to become more sluggish. Studies show that ingesting only 2.2 mg fluoride daily, as from drinking 2 liters of fluoridated water daily (3 liters at .7 ppm), can slow thyroid function.”
Jacob Teitelbaum
MD, board certified internist, Director of the the Practitioners Alliance Network (PAN) and author of numerous books on fibromyalgia and chronic fatigue syndrome .
Several studies reviewed by the NRC (Fluoride in Drinking Water 2006) reported associations between dental fluorosis and increased risk of adverse health effects, including thyroid disease, lowered IQ, and bone fracture.”
For an overview of fluoride’s effect on the endocrine system and especially the thyroid gland, including three recent and highly-relevant studies, please refer to our article: 
Fluoride and the endocrine system
“In humans, effects on thyroid function were associated with fluoride exposures of 0.05-0.13 mg/kg/day when iodine intake was adequate and 0.01-0.03 mg/kg/day when iodine intake was inadequate.” p.262-3
US National Research Council
2006 Review: Fluoride in Drinking Water
More thyroid quotes
More thyroid studies
Recent studies

(Not in chronological order)

Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water
“We found that higher levels of fluoride in drinking water provide a useful contribution for predicting prevalence of hypothyroidism. We found that practices located in the West Midlands (a wholly fluoridated area) are nearly twice as likely to report high hypothyroidism prevalence in comparison to Greater Manchester (non-fluoridated area). In many areas of the world, hypothyroidism is a major health concern and in addition to other factors—such as iodine deficiency—fluoride exposure should be considered as a contributing factor. The findings of the study raise particular concerns about the validity of community fluoridation as a safe public health measure.”
Journal of Epidemiology and Community Health: July 2015

Fluoride exposure and thyroid function among adults living in Canada: Effect modification by iodine status
“Adults living in Canada who have moderate-to-severe iodine deficiencies and higher levels of urinary fluoride may be at an increased risk for underactive thyroid gland activity.”
“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,” said lead author Ashley Malin.
Environment International: December 2018

Fluoride-induced developmental disorders and iodine deficiency disorders as examples of developmental disorders due to disturbed thyroid hormone metabolism
“Both exposure to fluoride and iodine deficiency during early development can lead to disturbed thyroid hormone metabolism and produce the same spectrum of developmental disorders including short stature, bone deformities, cognitive impairment, delayed dental eruption, and dental fluorosis.”
Fluoride Research:  October-December 2018

Fluoride thyroid hormone derangements and its correlation with tooth eruption pattern among the pediatric population from endemic and non-endemic fluorosis areas 
“Positive correlation exists between fluorosis and thyroid functional.”
The Journal of Contemporary Dental Practice: December 2018

A systematic analysis on possibility of water fluoridation causing hypothyroidism
“The present systematic review suggests a positive correlation between excess fluoride and hypothyroidism. This calls the need for further well-controlled studies in this otherwise emerging alarming issue.”
Indian Journal of Dental Research: June 2018

Impact of drinking water fluoride on human thyroid hormones: A case-control study
“The major finding of this study is that TSH values are higher with a higher fluoride concentration in the drinking water, even for generally low fluoride concentrations. This is seen both in cases of untreated hypothyroidism and in controls. Controls, with normal thyroid function, also have higher TSH values with higher fluoride concentrations, even though their TSH values are still within the normal range. TSH values are higher (in both cases and controls) with higher levels of water consumption. This is consistent with an association between increased fluoride intake (due to increased water consumption) and increased TSH. It was found that F impacts human thyroid hormones, especially TSH and T3 even in the standard concentration of less than 0.5 mg/L.
Scientific Reports: February 2018

Dental fluorosis, nutritional status, kidney damage, and thyroid function along with bone metabolic indicators in school-going children living in fluoride-affected hilly areas of Doda district, Jammu and Kashmir, India
“There was a significant decrease in thyroid-stimulating hormone (TSH) in the affected area school children compared to control. In conclusion, fluorotic area school children were more affected with dental fluorosis, kidney damage, along and some bone indicators as compared to control school children.”
Environmental Monitoring and Assessment: November 2017

Relevant quotes on fluoride and the thyroid gland
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“It is unsafe for many people; it can harm babies that are bottle fed and it can make it worse for individuals with impaired thyroid function. Toxins are very abundant in our environment and we need to reduce them whenever it is possible, so adding a known toxin to water makes no sense.”
Eve-Marie Arcand
DDS
“The impact on the thyroid is probably the reason for lowered IQ and ADHD. Lowered thyroid function is also well known to cause weight gain, lethargy and depression. Our children should not be subjected to a toxin, unbeknown to them, via their drinking water. Also, if I bathe in it, my skin breaks out in painful, weeping eczema, which feels like a bad case of sunburn.”
Michael Brathwaite
MA
“Many of the children in the study group showed a marked delay in the eruption of deciduous teeth…. in many cases by as much as a year from accepted eruption dates….. Delay in dentition, as described, is in accord with the work of De Eds, Baume and Becks, and Orban, who suggested that fluoride inhibited thyroid function which in turn delayed the eruption of the teeth.”
R. Feltman & G. Kosel
Prenatal and postnatal ingestion of fluorides - fourteen years of investigation - Final Report. 1961; J. dent. Med., 16: 190-199.
“Right now we have 1 in 6 children in the U.S. with neurodevelopmental brain disease, including ADHD, Autism Spectrum Disorders, low IQ and behavioral disorders, and 1 in 8 women who will develop thyroid disease. These two epidemics tell us that chemicals like fluoride and lead, both developmental neurotoxins and endocrine disruptors, have no place in our public water."
Angela Hind
MD
“There are numerous mechanisms by which uncontrolled dosing of fluorides through water fluoridation can potentially harm thyroid function, the body and the brain… I support federal investigative hearings looking into why our cities and towns are allowed to continue to add fluoride to public water sources.”
Mark Hyman
MD, NIH scholar, medical correspondent and author
“I recently served on a city council appointed by the mayor to study the issue of fluoridation. Based on 2 years of studying the literature and closely examining the 2006 NAS/NRC report, the council persuaded the Assembly members of Juneau (Alaska) to remove fluoride from the city water. My particular interest was the effect of fluoride on IQ. Recent Chinese studies show a significant reduction of IQ in children drinking water with high natural fluoride levels (compared to children in low fluoride communities). Fluoride is also very bad for thyroid function; hyperthyroidism (Graves disease) used to be treated with fluoride, but this treatment was abandoned because of it being too toxic.”
Emily Kane
ND, LAc, Author, Managing Menopause Naturally, Member of mayoral commission to re-examine risk/benefit of fluoridation, Juneau, AK
“It was found that F impacts human thyroid hormones, especially TSH and T3 even in the standard concentration of less than 0.5 mg/L.”
Z. Kheradpisheh et al.
Impact of Drinking Water Fluoride on Human Thyroid Hormones: A Case- Control Study (2018)
“The health risks from fluoridation to the brain, bones, thyroid, and kidneys far outweigh any benefits to teeth. It is unethical to force exposure to fluoridation chemicals on entire populations without consent.”
Kristie Lavelle
OTR/L, CHT
“Fluoridation causes dental fluorosis, which is associated with lowered IQ and thyroid gland interference. Fluoridation chemicals are contaminated with arsenic and trace radionuclides, which contribute to the carcinogenic potential of tap water. The benefit is only about one tooth saved per person from dental decay after a lifetime of fluoridation so the benefits are miniscule compared to the known harm fluoridation causes.”
Hardy Limeback
DDS, Ph.D.
“We found that practices located in the West Midlands (a wholly fluoridated area) are nearly twice as likely to report high hypothyroidism prevalence in comparison to Greater Manchester (non-fluoridated area).”
Professor Stephen Peckham et al.
Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water (2015)
“As practitioners helping people with hormone balance for 30 years, it is our strong feeling that fluoridation is a contributing factor to the massive epidemic of low thyroid function affecting tens of millions of Americans. We consider fluoridation to be one of the greatest hoaxes perpetrated upon the American public, up there with estrogen supplementation for all women. Shame on the ADA and the CDC! As we say in our recent book, FEELING FAT, FUZZY OR FRAZZLED,” ‘Fluoridation is simply a bad idea whose time has passed.’”
Karilee H. Shames
PhD, RN, Advance Practice Holistic Nurse and Richard L. Shames, MD, 35 years GP experience, co-authors ”Feeling Fat, Fuzzy or Frazzled?” and “Thyroid Power”.
“Fluoride ingestion increases the risk for thyroid disease, among many health concerns. Given the epidemic of thyroid problems, as a patient advocate, I’m convinced that our health is far better served by minimizing the intake of this unnecessary toxin.”
Mary Shomon
Leading thyroid patient advocate and best-selling author of the “Thyroid Diet”
“Among the many health-damaging effects of Fluoride, is its harmful effect on the thyroid. It is no surprise Hashimoto's thyroiditis and hypothyroidism is at epidemic levels, which dramatically impacts a person's quality of life and ability to function effectively.”
Robban Sica
MD
“Several papers reviewed by the NRC (2006a) have reported associations between dental fluorosis and increased risk of adverse health effects, including thyroid disease, lowered IQ, and bone fracture.”
Kathleen Theissen
PhD
“I write books about oral/systemic medicine and it is unbelievable to me that we still think fluoridation is a great idea due to all the unforeseen consequences of adding fluoride as a "medication" to water. Even a popular biology lecturer came to Austin and lectured hygienists here of her turn around on the issue after she nearly died from hypothyroidism and took a closer look.”
Carol Vander Stoep,
RDH, BSDH
“Fluoride has detrimental effects on the health of pets that are supplied with fluoridated water. Fluoride affects the functionality of their thyroid gland and subsequently hormonal status. Our renal patients are negatively affected by this addition. I am concerned about fluoride uptake into bone. There is scant pet animal research in this area, however I suspect similar levels of fluoride in dog and cat joints is contributing to pain, inflammation and disease. Many pet owners are unaware of the impact this unnecessary addition to their pets vital water supply is having on their pets overall health. It must end.”
Heidi Ward- McGrath
BVSc
“Iodine is the key that turns on the thyroid’s energy engine, but fluoride intake causes thyroid cells to pick up fluoride instead, causing the thyroid to become more sluggish. Studies show that ingesting only 2.2 mg fluoride daily, as from drinking 2 liters of fluoridated water daily (3 liters at .7 ppm), can slow thyroid function.”
Jacob Teitelbaum
MD
Other studies and references
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Bachinskii PP et al. 1985. Action of the body fluorine of healthy persons and thyroidopathy patients on the function of hypophyseal-thyroid the system. Probl Endokrinol (Mosk) 31(6):25-9.

Burgi H, et al. (1984). Fluorine and the Thyroid Gland: A Review of the Literature. Klin Wochenschr. 1984 Jun 15;62(12):564-9.

Caldwell KL, et al. (2008). Iodine status of the U.S. population, National Health and Nutrition Examination Survey 2003-2004. Thyroid 18(11):1207-14.

Choi AL, et al. (2012). Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis. Environmental Health Perspectives 2012 Jul 20.

Galletti P, Joyet G. (1958). Effect of fluorine on thyroidal iodine metabolism in hyperthyroidism. Journal of Clinical Endocrinology 18(10):1102-1110.

Gas’kov A, et al. (2005). The specific features of the development of iodine deficiencies in children living under environmental pollution with fluorine compounds. Gig Sanit. Nov-Dec;(6):53-5.

Gencer B, et al. (2012). Subclinical thyroid dysfunction and the risk of heart failure events: An individual participant data analysis from six prospective cohorts. Circulation 2012 Jul 19.

Guan ZZ, et al. (1988). Synergistic action of iodine-deficiency and fluorine-intoxication on rat thyroid. Chinese Medical Journal 101(9):679-84.

Hong F, et al. (2001). Research on the effects of fluoride on child intellectual development under different environmental conditions. Chinese Primary Health Care 15: 56-57.

Hosur MB, et al. (2012). Study of thyroid hormones free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) in subjects with dental fluorosis. European Journal of Dentistry 6:184-90.

Klein RZ, et al. (2010). Relation of severity of maternal hypothyroidism to cognitive development of offspring. Journal of Medical Screening 8(1):18-20.

Haddow JE, et al. (1999). Maternal thyroid deficiency during pregnancy and subsequent neuropsychological development of the child. New England Journal of Medicine 341(8):549-55.

Lin F, et al (1991). The relationship of a low-iodine and high-fluoride environment to subclinical cretinism in Xinjiang. Endemic Disease Bulletin 6(2):62-67 (republished in Iodine Deficiency Disorder Newsletter Vol. 7(3):24-25).

Lin F, et al. (1986). A preliminary approach to the relationship of both endemic goiter and fluorosis in the valley of Manasi River, Xin-Jiang to environmental geochemistry. Chinese Journal of Endemiology 5(1):53-55.

Maumené E. (1854). Experiencé pour déterminer l’action des fluores sur l’economie animale. Compt Rend Acad Sci (Paris) 39:538-539.

Mikhailets ND, et al. (1996). Functional state of thyroid under extended exposure to fluorides. Probl Endokrinol (Mosk) 42:6-9.

National Research Council. (2006). Fluoride in drinking water: a scientific review of EPA’s standards. National Academies Press, Washington D.C.

Peckham S, et al. (2015). Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water. Journal of Community Health & Epidemiology.

Pontigo-Loyola A, et al. (2008). Dental fluorosis in 12- and 15-year-olds at high altitudes in above-optimal fluoridated communities in Mexico. Journal of Public Health Dentistry 68(3):163-66.

Ren D, et al. (1989). A study of the intellectual ability of 8-14 year-old children in high fluoride, low iodine areas. Chinese Journal of Control of Endemic Diseases 4:251.

Rodondi N, et al. (2010). Subclinical hypothyroidism and the risk of coronary heart disease and mortality. JAMA 304(12):1365-74.

Susheela AK, et al. (2005). Excess fluoride ingestion and thyroid hormone derangements in children living in New Delhi, India. Fluoride 38:98-108.

Wang X, et al. (2001). Effects of high iodine and high fluorine on children’s intelligence and thyroid function. Chinese Journal of Endemiology 20(4):288-90.

Xu Y, et al. (1994). The effect of fluorine on the level of intelligence in children. Endemic Diseases Bulletin 9(2):83-84.

Yang Y, et al. (1994). The effects of high levels of fluoride and iodine on intellectual ability and the metabolism of fluoride and iodine. Chinese Journal of Epidemiology 15(4):296-98 (republished in Fluoride 2008; 41:336-339).

Yao Y, et al. (1996). Analysis on TSH and intelligence level of children with dental Fluorosis in a high fluoride area. Literature and Information on Preventive Medicine 2(1):26-27.

Yu Y. (1985). Study on serum T4, T3, and TSH levels in patients with chronic skeletal fluorosis. Chinese Journal of Endemiology 4(3):242-43.

Zhao W, Zhu H, Yu Z, Aoki K, Misumi J, Zhang X. 1998. Long-term effects of various iodine and fluorine doses on the thyroid and fluorosis in mice. Endocrine Regulation 32(2):63-70.