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Nutrient Spotlight—Fluoride

Author: Kimberly Day

Tuesday, 30 September 2014

There are strange dichotomies we experience every day in the natural world. For example, sunlight provides you with natural vitamin D that you need to protect virtually every single body system. However, too much sunlight can also increase your risk for wrinkles, premature aging and even skin cancer.

Similarly, simply being “natural” doesn’t always equate with healthy. Think poppies and opium, arsenic and mercury.

And now, something that we’ve been conditioned and even preached to believe is not only good for us, but actually critical for oral health is, in fact, quite toxic, especially when use in excess.

We are talking about fluoride.

What is Fluoride?

Fluoride is a component of the element fluorine. It is often found is salt form and is considered a halide, along with bromide, chlorine and iodine. As such, it often competes with these elements in the body. This can lead to iodine deficiency.

For years, fluoride was heralded for its use in oral and dental health. In fact, the Centers for Disease Control and Prevention (CDC) have even gone so far as to call the fluoridation of public water (to prevent tooth decay), “One of 10 great public health achievements of the 20th century.”1 However, as you’ll read below, many question the health and safety of this practice.

Beyond its inclusion in drinking water, fluoride is found naturally, in small quantities, in several foods and beverages, including seafood, gelatin, black tea, raisins, wine, baked potatoes, lamb and carrots.

The USDA lists the RDA of fluoride to be 10 mg per day for adults and 0.7-2.2 mg a day for infants and small children.2 In three liters of fluorinated water (about 12.7 cups), there are 2.4 mg of fluoride. Add in brushing twice a day with fluoride toothpaste and you can start to up those numbers pretty quickly.

Then there’s the fact that most natural health practitioners believe that fluoride itself is downright toxic.

Conditions Affected by Fluoride

- Brain health
- Dental health
- Thyroid health
- What Does the Research Say?

Brain Health

Fluoride’s effect on brain health lies mainly in its negative interaction with iodine.

One study found that fluoride competes with iodine in the body and is a cause of iodine deficiency. Iodine is critical when it comes to providing energy metabolism in brain cells.3

It can be particularly problematic for women who choose to formula feed their babies. While many pediatricians advocate for using fluorinated water to mix with the formula, natural health practitioners advise to steer clear.

A review of the medical literature published in October 2012 found that children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas.4 This led the researchers to conclude, “The results support the possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment.”

Dental Health

Research into fluoride began in 1901, but it wasn’t until 1944 that the first large-scale study of fluoridated water and its effect on tooth decay began in Grand Rapids, Michigan. During that 15-year study, researchers found that the cavities among children born after the city added fluoride to the water supply dropped by more than 60 percent.5

Even today, fluoride continues to be dental medicine’s main weapon in the battle against tooth decay. Almost every toothpaste on the market contains fluoride, and more than 200 million Americans drink fluoridated water.5

Interestingly, the fluoride that is added to the water supply is not a natural substance. It is the byproduct of fluorine gas used by the aluminum and nuclear industries.6

However, the safety of fluoride remains hotly debated, mainly because, in addition to preventing cavities, it also potentially causes a whole slew of negative problems. In fact, further research even challenges the notion that fluoride prevents tooth decay,7 and links it to oral, bone, liver and thyroid cancers,6 as well as infertility.8-9

Fluoride has direct antibacterial properties at high levels and it binds to enamel to protect the teeth from acid produced by oral bacteria. However, new research is now showing that it doesn’t always kill the bacteria.10 This is because bacteria can overcome the effects of fluoride and become resistant to it.

In the study, Yale researchers report that bacteria have the ability to monitor levels of fluoride. When these levels increase, fluoride riboswitches are activated. Riboswitches are messenger RNA structures that sense specific metabolites such as fluoride, while rejecting other similar molecules such as chloride, and subsequently modulate gene expression.

The riboswitches promote expression of genes that encode presumed fluoride transporters, enzymes that fluoride is known to inhibit, as well as additional proteins of unknown function.

The study authors suggest that understanding the mechanism in which organisms resist the toxic effects of fluoride may have future application to oral health.

A good alternative to fluoride is to look for toothpastes that contain the natural sweetener xylitol or chew xylitol gum or mints, as shown in several studies. For example, in February 2012, researchers reported that xylitol chewing gum and tablets improved dental health in mothers and children.11

Sixty mother and child pairs with elevated levels of salivary mutans streptococcus—a common bacteria found in the mouth and associated with dental cavities—received either xylitol supplements or fluoride varnish (a yellowish coating painted over teeth to prevent cavities).

In the xylitol group, the mothers chewed xylitol gum and the children received chewable tablets three times per day for three months. All subjects received oral hygiene instructions, dietary counseling and restorative treatment. The investigators performed dental examinations at six, 12 and 18 months to assess cavities, dental plaque and salivary mutans streptococcus levels.

After 18 months, the number of subjects with elevated salivary mutans streptococcus decreased in the xylitol group compared to levels at the beginning of the study. At six and 12 months, the children demonstrated significantly decreased levels of plaque in the xylitol group compared to the control group. At 18 months, the plaque levels in the mothers receiving xylitol decreased compared to levels at the beginning of the study. In the control group, the number of dental cavities increased throughout the experiment.

The study authors stated, “The use of xylitol chewing gum by mother and chewable tablets by children showed significant reduction of mutans streptococcus count, plaque score as well as caries [cavities] experience.”

Thyroid Health

Because of water fluorination and the widespread use of fluoride toothpaste, a massive number of people are exposed to fluoride, which spells trouble for the thyroid gland. In fact, according to the National Research Council (NRC), consuming 0.01 to 0.03 mg/kg/day of fluoride can severely inhibit proper thyroid function.6

To this point, in one study, researchers evaluated thyroid function in rats consuming a diet with added fluoride. The rats were evaluated for serum levels of the thyroid hormones T3, free T3, T4 and free T4. The results of the study showed that the rats fed the diet with added fluoride had significantly decreased levels of all four thyroid hormone measurements.12

But what about in humans? Turns out similar effects occurred in a study of 123 subjects evaluated for thyroid hormone levels. Prolonged consumption of drinking water with elevated levels of fluoride caused an increase in thyroid stimulating hormone (TSH) released from the pituitary, decreased levels of T3 and a more intense absorption of radioactive iodine by the thyroid as compared to healthy individuals who consumed drinking water with the normal fluorine concentration.13

Another study evaluated thyroid and immune function in individuals exposed to fluoride at work. The researchers showed that in the workers with subclinical hypothyroidism (low thyroid), T3 was reduced in 51 percent of subjects exposed to the fluoride. Furthermore, alterations in immune system function were more pronounced in these workers, causing increased numbers of T-lymphocytes (white blood cells), but decreased functional activity of these cells.14

How to Use Fluoride

It is perhaps no coincidence that many of the healthiest countries of the world do not fluoridate their water. Of the top 10 healthiest countries—Japan, Australia, France, Sweden, Italy, Spain, Greece, Switzerland, Monaco and Andorra—the majority do not fluoridate their water.

Australia is the only one of these countries to have instituted a widespread water fluoridation program, providing fluoridated water to 70 percent or more of its population. Switzerland and France don’t practice artificial water fluoridation, but they do add fluoride to their salt. In Spain, only 10 percent of the population receives fluoridated water (although salt is fluoridated) and less than one percent of Japan practices water fluoridation. Italy, Greece and Sweden don’t practice water fluoridation.

Given this, you would do well to avoid drinking fluorinated water, opting instead for distilled or filtered water.

Similarly, you may want to swap your fluoride toothpaste for one that contains xylitol. Depending on where you live, fluoride-free toothpaste can be hard to come by. One readily available brand is Tom’s of Maine. Just be sure to read the box carefully, as they make both fluoride and fluoride-free options.


Bourre JM. J Nutr Health Aging. 2006 Sep-Oct;10(5):377-85.
Morales E, et al. Epidemiology. 2012;23:64-71.
National Institute of Dental and Craniofacial Research. www.nidcr.nih.gov/oralhealth/topics/fluoride/thestoryoffluoridation.htm.
Kumar N, et al. Toxicol Int. 2012 May-Aug;19(2):182-7.
Izquierdo-Vega JA, et al. J Appl Toxicol. 2010 Nov 19. doi:10.1002/jat.1600.
Baker JL, et al. Science. 2011 Dec 22. [Epub ahead of print.]
Alamoudi NM, et al. Saudi Med J. 2012;2:186-92.
Wang H, et al. Toxicol Ind Health. 2009 Feb;25(1):49-57.
Bachinskii PP, et al. Probl Endokrinol (Mosk). 1985 Nov-Dec;31(6):25-9.
Balabolkin MI, et al. Ter Arkh. 1995;67(1):41-2.

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