Among many fluoride dangers, the toxic effects of high amounts of fluoride on the thyroid gland have been known for decades. But what about lower amounts, like the levels commonly found in fluoridated drinking water? Despite the lack of research in the area of chronic, low-dose fluoride exposure, researchers and health organizations have asserted for decades that these lower doses do not disrupt thyroid function. This widely accepted stance may change, however, now that results of a new, first-of-its-kind study have been released. The study’s findings indicate that artificial fluoride added to your drinking water may be toxic to your thyroid and increase your risk for hypothyroidism.[1]

Higher levels of fluoride in drinking water are associated with an increased risk for hypothyroidism

The UK-based study is the first population-level study to investigate the association between fluoride levels in drinking water and hypothyroidism. Drinking water is the most significant source of ingested fluoride in the United Kingdom, and likely in the United States as well. The British researchers analyzed differences in rates of hypothyroidism between areas where water is fluoridated and where it is not.

Almost 8,000 general medical practices covering around 98% of the English population provided information on rates of hypothyroidism, and fluoride levels across England were mapped against these practice areas. The analysis aimed to determine whether prevalence of hypothyroidism was affected by practice populations being situated in fluoridated areas, defined as 0.7 mg/L (0.7 ppm) or more, or in those areas with lower levels of fluoride, 0.3 mg/L or less.

Hypothyroidism risk nearly doubles with fluoridated drinking water

After the researchers accounted for the major known predictors of thyroid function, including age, sex, iodine intake, and perchlorate exposure, they found the odds of high levels of hypothyroidism were 1.6 times higher in high-fluoride areas (those with fluoridated water) than it was in areas with low fluoride (no fluoride added to drinking water). West Midlands, a completely fluoridated area (0.7 mg/L or more), had nearly twice the risk for hypothyroidism then Greater Manchester, a nonfluoridated area (0.3 mg/L or less).

“On the whole, we think there’s a 9% elevated or excess hypothyroidism prevalence across England due to fluoridation of drinking water,” said the study’s lead author, Stephen Peckham, Professor of Health Policy and Director at the Center for Health Services Studies at the University of Kent in the United Kingdom.[2] Given that the researchers were only able to look at diagnosed hypothyroidism, there are likely other cases of impaired thyroid function that have not yet been diagnosed, so fluoride dangers to the thyroid may actually be higher than this study found.

Professor Peckham and his colleagues believe the study “raises questions about the safety of community fluoridation.” Harvard’s Philippe Grandjean, MD, from the School of Public Health, agreed in a recent interview, suggesting that the study’s results should prompt a rethinking of the whole practice of adding fluoride to drinking water.[2]

Other fluoride dangers

The current study results only add to the growing list of concerns about fluoride dangers. In addition to hypothyroidism, chronic fluoride ingestion has been linked with cancer, cognitive impairment, and derangements of certain cellular enzymes and electrolytes.[3] In addition, fluoride replaces calcium in teeth and bone, causing dental and skeletal fluorosis. While dental fluorosis is considered to be merely a cosmetic issue—it causes white and brown stains and pitted tooth enamel—skeletal fluorosis is a chronic bone disorder causing joint pain, back pain, and numbness and tingling in the extremities. The prevalence of skeletal fluorosis is unknown, but about 41% of children in the United States, where water has been fluoridated at an average level of 1 ppm, have varying degrees of dental fluorosis, and the rates are increasing.[3] That’s likely because in addition to fluoridated water, fluoride is ingested through dental care products, processed foods, and commercial beverages.

What about topical fluoride?

In addition to reducing your fluoridated water intake, avoid the use of toothpaste, mouthwash, and home-based topical treatments that contain fluoride, particularly in children as they tend to ingest more and are more susceptible to the toxic effects.[4] Evidence shows that fluoride from toothpaste and especially mouthwash stays in the saliva and gets absorbed.[5] If you want your child to receive potential fluoride benefits for prevention of tooth decay, topical treatments at the dentist’s office are a safer option than other methods.

What you can do to minimize fluoride dangers

Unfortunately, most faucet, refrigerator, and carafe filters do not remove fluoride. Therefore, even though your water may taste better by using these filters, they will leave you and your family vulnerable to fluoride dangers. Your best bet for protection is to use more efficient water filtration. Our article here discusses the different types of filters for different price levels.

Another thing you can do is make sure you are getting plenty of iodine, calcium, magnesium in your diet. Fluoride unfortunately substitutes itself for iodine in thyroid hormone production, and replaces calcium and magnesium in bones and teeth. The more deficient you are in these essential minerals, the more likely fluoride replaces them, causing harm.[3] Lastly, preliminary studies indicate that increasing your phytonutrient intake by eating plenty of plant-based foods can help protect your thyroid against fluoride-induced toxicity. Both resveratrol (a phytonutrient from grapes) and spirulina  (a nutrient-rich algae), for instance, have been shown to protect the thyroid against fluoride toxicity, restoring the thyroid’s structure and ability to produce thyroid hormones.[6,7] In addition to drinking red wine and grape juice, you can get resveratrol by taking a supplement. The typical supplemental dose is 200 mg of trans-resveratrol per day. Spirulina is best taken as a powder rather than as capsules or tablets. A typical spirulina dose is 3 grams per day.

[1] J Epidemiol Community Health. 2015 Feb 24.

[2] Medscape Medical News. March 4, 2015.

[3] ScientificWorldJournal. 2014; 2014: 293019.

[4] Neurologia. 2011 Jun;26(5):297-300.

[5] Biol Trace Elem Res. 2010 Nov;137(2):159-67.

[6] Biol Trace Elem Res. 2014 Dec;162(1-3):278-87.

[7] Food Chem. 2013 Sep 1;140(1-2):321-31.