Water Fluoridation Linked to Diabetes and Low IQ

Story at-a-glance

  • New research found drinking fluoridated water may be associated with an increased risk of diabetes
  • The data revealed a 1 milligram (mg) increase in added fluoride to drinking water was associated with a 0.17 percent increase in diabetes prevalence
  • Watch professor Paul Connett, director of the Fluoride Action Network (FAN), debate professor Mike Berridge of the Malaghan Institute of Medical Research in New Zealand on the topic of water fluoridation


This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.

By Dr. Mercola

In the video above, you can watch professor Paul Connett, Ph.D., director of the Fluoride Action Network (FAN), debate professor Mike Berridge, Ph.D., of the Malaghan Institute of Medical Research in New Zealand on the topic of water fluoridation.

This debate was 12 years in the making; it's taken that long to find someone willing to debate Connett and defend the controversial practice of water fluoridation. It's a pressing issue in the U.S. as well as in New Zealand, one of the few countries in the world where water fluoridation is still practiced.

At present, only about 52 percent of New Zealand's population receives fluoridated water, but proposed legislation could change this and essentially require mandatory water fluoridation for all of New Zealand.1

In order to support this introduction of mandatory water fluoridation, the New Zealand Ministry of Health recently called on an expert panel to review the data surrounding water fluoridation, and the panel, not surprisingly, concluded it is safe.

However, information provided by Connett in the debate should easily undermine the fluoridation mandate, as the practice has been linked to a number of health harms, including lowered IQ.

Fluoride Proponents Make Error in Reviewing IQ Study, Inaccurately Claim Fluoridation Is Safe

In 2014 Lancet Neurology released a study, authored by a Harvard doctor, among others, that classified fluoride as a developmental neurotoxin.2 It wasn't the first time.

In 2012, a meta-analysis, also by Harvard researchers, clearly showed that children exposed to fluoride in drinking water had lower IQ, by an average of seven points, in areas with raised concentrations.3

This study was used by the New Zealand fluoride panel to support fluoride safety, because the researchers mistakenly said the meta-analysis found the average lowering of IQ was less than one point.

Even after they corrected their mistake, they did not make it clear that the correction meant fluoride was harmful to children's neurodevelopment. According to FAN:4

"It was not a drop of half an IQ point but a drop of half of one standard deviation, which is the equivalent of [seven] IQ points. That is a very big difference!

The [Sir Peter] Gluckman [Prime minister's chief scientific adviser] and [Sir David] Skegg [president of the Royal Society of New Zealand] team [who headed up the expert panel] 'corrected' this mistake in an updated version of their report.

But they corrected their mistake in a way that would not be clear to the layperson but worse still made this change without changing the conclusion derived from the mistake.

This conclusion — for anyone knowledgeable on the subject — is ridiculous, but unfortunately many will be deceived by this manipulation and conclude there is no problem with fluoride's neurotoxicity — and specifically its ability to lower IQ in children.

So we are left with a very uncomfortable question, did Gluckman and Skegg and their advisers simply make a clumsy mistake, or was this a deliberate attempt to deceive the public?"

Cherry-Picked Data and Another Flawed Review

Another issue with the panel's "expert" report had to do with their reliance on a 2015 study that found no IQ difference between a fluoridated and non-fluoridated community.5 This study was also cited by Berridge in support of fluoridation in the video above.

However, here, too, is a case of a flawed review, intentional or otherwise. As FAN reported, the study had virtually no controls.

It compared a fluoridated community of 900 children with a non-fluoridated community of less than 90, about half of which took fluoride supplements. So there was no way to accurately gauge any fluoride-related IQ differences.

The panel focused only on the aforementioned Harvard meta-analysis and this flawed IQ study — completely ignoring the more than 300 animal and human studies previously published that point to fluoride's role as a neurotoxin.6

New Study Looks Into Fluoride-Diabetes Connection

More than 9 percent of the U.S. population suffers from diabetes, more than a quarter of which remain undiagnosed.7 Diabetes rates have nearly quadrupled over the last three decades and they continue to rise.

While dietary factors and inactivity certainly play a role in the U.S. diabetes epidemic, research conducted by Kyle Fluegge, Ph.D., a health economist for New York City's health department who completed the research as a post-doctoral fellow at Case Western Reserve University in Cleveland, Ohio, tested the hypothesis that water fluoridation may be involved.

Drinking Fluoridated Water May Increase Diabetes Risk

Fluegge's study used mathematical models to analyze data on fluoride levels in water and rates of diabetes in 22 U.S. states.8

The data revealed a 1 milligram (mg) increase in added fluoride was associated with a 0.17 percent increase in age-adjusted diabetes prevalence, even after adjusting for other diabetes risk factors like obesity and physical inactivity. There were also differences noted depending on which type of fluoride was found in the water.

Sodium fluoride was the first of the fluoride waste materials to be used for fluoridation, but now it is rarely used.

It's the most well known, as this is the compound used as pharmaceutical grade in toxicology studies and other research into the potential health dangers of fluoride. In the recent study, sodium fluoride was linked to an increased risk of diabetes, as was sodium fluorosilicate.

Is Arsenic Contamination in Fluoride to Blame?

For reasons that are unclear, another fluoride type, fluorosilicic acid, was associated with decreases in diabetes, as was naturally occurring fluoride. As noted by Fluoride Action Network (FAN), each of these fluoride varieties is a byproduct of the fertilizer industry and subject to contamination with arsenic.9

"In the process of converting phosphate rock into soluble fertilizer, two very toxic fluoride gases are released: hydrogen fluoride and silicon tetrafluoride … Eventually, as a result of both litigation and regulation, the phosphate industry installed 'wet scrubbers' to trap the fluoride gases.

The collected liquid in these scrubbers (hydrofluoroslicic acid) is entered into storage tanks and shipped to water departments throughout the country … After being captured in the scrubbing system, the fluorosilicic acid is either shipped as is (an acidic liquid), or is converted into dry powders (sodium fluorosilicate and sodium fluoride).

Whether shipped in its original liquid form, or converted into powder, the fluorosilicic acid does not undergo purification procedures. As a result, fluorosilicic acid has been found to contain various contaminants, particularly arsenic."

Although this is speculative, it's worth noting that chronic arsenic exposure may be linked to an increased risk of diabetes.10 FAN continued:11

"The level of arsenic found in fluoridation chemicals is not trivial. According to a review in the American Water Works Association's publication Opflow, the amount of arsenic that fluoridation adds to finished water 'is hardly a minimal amount.' The arsenic problem is unique to fluoridation chemicals as no other water treatment chemical has a problem with arsenic contamination."

Tooth Decay Rampant in Low-Income Children Despite Widespread Fluoridation

African American and Mexican American children have significantly higher rates of dental fluorosis, and many low-income urban communities also have severe oral health crises, despite decades of water fluoridation.

The New York State Coalition Opposed to Fluoridation, Inc. (NYSCOF) reported that rates of tooth decay among low-income children are on the rise even though record numbers of these children are exposed to fluoridated water (as well as fluoride from other sources, including dental products and medications).

Data set to be presented at an American Public Health Association (APHA) Meeting in November 2016 revealed 40 percent of 3- to 5-year-olds living 100 percent below the federal poverty level have tooth decay, along with 69 percent of 6- to 9-year-olds and 74 percent of 13- to 15-year-olds.

Rates of dental fluorosis also rose among this population, with 58 percent of low-income children affected by this condition.12 Paul Beeber, NYSCOF president, said in a news release:13

"Claims that poor children need fluoride are without merit or evidence … It's the dental care delivery system that needs fixing. Low-income Americans need dental care not fluoride."

The Risks of Water Fluoridation Are Scientifically Proven

In 2015, the Cochrane Collaboration released a comprehensive review with points that are nearly impossible to dispute. Fluoride doesn't work to prevent cavities and it's proven to cause harm in the form of dental fluorosis.

The Cochrane Collaboration is considered to be the gold standard in evidence-based reviews, and only three studies conducted since 1975 had enough merit to be included. None showed that swallowing fluoride prevents cavities while it was clear that it causes harm (dental fluorosis).

Dental fluorosis, a condition referring to changes in the appearance of tooth enamel caused by long-term ingestion of fluoride, is not purely aesthetic. It can lead to crumbling of tooth enamel in its advanced stages, and consuming excess fluoride is also linked to learning problems, thyroid disease and bone problems.

Worse still, even the "best" studies identified by the Cochrane Collaboration were not considered to be high-quality and nearly all were flawed, for instance, failing to control for other contributing factors, such as dietary sources of fluoride aside from tap water, diet and ethnicity.

Fluoride's Toxic Effects Are Cumulative

It's important to understand that the effects of fluoride are cumulative, which means consuming it via your tap water, daily for a lifetime, may lead to increasingly worsening symptoms of fluoride poisoning (although children are also at an increased risk of harm).

Research, for instance, has linked fluoridated water consumption to thyroid dysfunction, weight gain, and depression. Your pineal gland also tends to accumulate significant amounts of fluoride, which eventually causes it to calcify. This may lead to ADHD-like symptoms and may also play a role in Alzheimer's and bipolar disease. Considering its effect on neurotransmitters, it's also quite conceivable that it might promote depression and other neurological disorders.14

Further, according to one 500-page scientific review, fluoride is an endocrine disruptor that can also affect your bones, brain and even your blood sugar levels.15 There are more than 100 published studies illustrating fluoride's harm to the brain alone, plus 43 more that directly link fluoride exposure to reduced IQ in children. Studies have also demonstrated that fluoride toxicity, caused by overexposure, can lead to:

Increased lead absorption

Disrupted synthesis of collagen

Hyperactivity and/or lethargy

Muscle disorders

Bone cancer (osteosarcoma)

Increased tumor and cancer rate


Skeletal fluorosis and bone fractures

Genetic damage and cell death

Damaged sperm and increased infertility

Inactivation of 62 enzymes and inhibition of more than 100

Inhibited formation of antibodies, and immune system disruptions


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