Fluoride: Understanding Its Effects on Health

Key takeaways:
~ Fluoride may help your teeth resist decay through increasing the resistance to acid produced by bacteria.
~ Too much fluoride is linked to skeletal and dental fluorosis, decreased IQ levels, and problems with thyroid hormone production.
~ Genetic variants impact your resilience to the negative effects of chronic fluoride consumption. Some people are more likely to be affected at lower levels, while others may not notice problems until fluoride exposure reaches higher levels.
~ There are many ways to reduce your exposure to systemic fluoride if you want to concentrate the fluoride on your teeth.

Members will see their genotype report below, plus additional solutions in the Lifehacks section. Consider joining today.  

Understanding Fluoride Health Effects: Dental Benefits and Potential Risks

Is fluoride good for you or bad for you? Should you avoid it in your drinking water? Filter it from your shower? Or should you get as much as you can for your dental health?

Like many health questions, whether fluoride is ‘good’ or ‘bad’ is not simple to answer. Instead, you’ll need to understand how fluoride is absorbed in the bones and teeth, how much is required, at what levels it is toxic, and how fluoride is eliminated from the body.

Some areas of the world have a lot more fluoride in the water than others, and diet (especially tea drinking) also plays a big role.

Additionally, genetic variants impact how well you detoxify fluoride.

Thus, the answer to the question – is fluoride good or bad – depends on many different elements.

Let’s dive into the science so that you can make informed decisions for yourself.

What is fluoride? Where does it come from?

Fluorine (chemical symbol F) is an element commonly found in minerals in the Earth’s crust. It is strongly reactive, so elemental fluorine is rarely found in nature. Instead, fluorine is incorporated into minerals or other compounds.

Fluoride (F⁻) is an ionic form of fluorine, and the name can commonly refer to several compounds that contain fluoride. For example, sodium fluoride, an ingredient in many kinds of toothpaste, is often referred to simply as fluoride.

How Does Fluoride Stop Tooth Decay?

According to the CDC: “Fluoride works by stopping or even reversing the tooth decay process—it keeps tooth enamel strong and solid. Certain bacteria in the mouth cause tooth decay. When a person eats sugar and other refined carbohydrates, these bacteria produce acid that removes minerals from the tooth’s surface. Fluoride helps to remineralize tooth surfaces and prevents cavities from forming.”[ref]

No offense to the CDC, but that didn’t really explain how fluoride stops tooth decay. Let’s dig into it further…

Fluoride ions are taken up by bone tissue and other supporting tissue, including the teeth, skin, and hair.[ref]

In tooth enamel, fluoride can do an ion exchange with hydroxyapatite, a calcium-containing compound that makes up part of your bones and tooth enamel.[ref]

Fluoride incorporates into the hydroxyapatite, forming fluorapatite, which is more resistant to the acidic pH caused by certain bacteria in the mouth. This facilitates enamel remineralization, preventing cavities from forming when acidity is high.

Toxicity of Fluoride: Health Effects and Concerns

Fluoride is toxic in higher amounts. The saying “the dose makes the poison” definitely applies to fluoride. The question is: At what level is fluoride OK, and at what level does it cause harm?

While sources on this vary just a little bit, the symptoms of acute fluoride poisoning may appear with as little as 1mg/kg of body weight. Thus, fluoride can be a problem for infants and small children at much lower levels than for adults.

According to Mt. Sinai hospital, symptoms of acute fluoride toxicity include:

• Abdominal pain, diarrhea, nausea and vomiting
• Abnormal taste in the mouth (salty or soapy taste), drooling
• Headache
• Irregular or slow heartbeat, heart attack (severe cases)
• Shallow breathing
• Tremors

Acute fluoride poisoning is fairly uncommon. One notorious case back in the 1940s was at the Oregon State Hospital. A patient at the mental hospital mistakenly brought cockroach poison made of sodium fluoride for the cooks to use in the kitchen instead of powdered milk. This caused acute fluoride poisoning in the Oregon State Hospital patients who ate the fluoride-laced food, with 47 resulting fatalities.[ref]

High fluoride in groundwater supplies:

Fluoride levels in the soil and water vary quite a bit. Most areas have natural fluoride levels in the water in the 10s to 100s of PPM (parts per million). However, in some areas of the world, fluorine concentrations in the water are high enough to cause health problems. This can be due to agricultural runoff (fertilizers), often combined with higher natural mineral levels in the water.[ref]

Average fluoride intake in the US:

Fluoride is now classified as a micronutrient, and the US has determined an adequate intake of 3 mg/day for women and 4 mg/day for men. The upper daily limit is set at 10 mg/day.

Long-term fluoride consumption:

Skeletal fluorosis is caused by long-term fluoride consumption at higher than tolerable levels. Skeletal fluorosis causes pain and damage to bones and joints due to the incorporation of fluoride into the bones and connective tissue.

The sources of fluoride people are commonly exposed to include drinking water (especially in some regions of the world with high natural fluoride), fluoride inhalation from burning coal, and fluoride from drinking a lot of tea. The largest source is tea consumption, especially in areas where the water also contains fluoride.[ref]

Researchers studied the causes of toxicity in fluorosis due to high fluoride water in a region in India. They found a reduction in PON1, acetylcholine esterase, and ATPase. Both the heart and liver also showed altered lactate dehydrogenase. The researchers concluded that higher fluoride levels in the water had a collective effect on cellular energy production in fluorosis patients.[ref]

Dental fluorosis:

While a little bit of fluoride may benefit enamel, too much fluoride can damage teeth. Excess fluoride, whether chronic or acute, can cause dental fluorosis, especially if it happens when the permanent teeth are developing (ages 0-3).

Enamel fluorosis initially causes whitish areas on the teeth. More severe enamel fluorosis causes pits and brown spots on the teeth.[ref]

Here’s what dental fluorosis can look like:

Permanent teeth are mineralized during the first three years of childhood, well before they come in.  Amoxicilin, a commonly used antibiotic, can increase the risk of mild fluorosis in teeth when exposed during a certain window of development. A study on kids with fluorosis found that exposure to amoxicillin between 20 and 24 months increased the risk of fluorosis by 3-fold. A previous study had also identified amoxicillin use between 3 and 6 months as slightly increasing the risk of fluorosis. The study does note that what is called fluorosis in these cases may be due to hypomineralization and not necessarily excessive fluoride exposure. [ref]

Intestinal Absorption and Excretion:

Fluoride is readily absorbed in the body. About 1% is absorbed in the mouth, with the rest absorbed in the stomach and small intestines. After absorption, the fluoride is transported throughout the body via the bloodstream. Concentrations in the bloodstream peak 20-60 minutes after consumption.

Approximately 50% of absorbed fluoride is excreted – mainly through urine. Adults retain a little less fluoride, and children retain a little more fluoride.

About 99% of the remaining fluoride is concentrated in the calcified tissues (e.g., bones, teeth), with 1% entering the soft tissues (e.g., brain, lungs, kidneys).[ref]

Pregnant women pass about 60% of the concentration of fluoride in their bloodstream to the placenta at lower levels. At high concentrations, the placenta acts as more of a barrier to protect the fetus from high fluoride levels. Fluoride also passes through breast milk at low concentrations.[ref]

How did fluoride get added to drinking water?

In many towns and cities in the US and Canada, low levels of fluoride are added to municipal water supplies.

The history of using fluoride for preventing cavities dates back a century or more. It was observed that people with mottled stains on their tooth enamel (fluorosis) were exposed to high natural fluoride levels in their drinking water. An epidemiological study showed that people averaged fewer cavities in areas with more prevalent dental fluorosis. In 1945, four US cities added 1mg/L of fluoride to their municipal water supplies, and they subsequently noted a decrease in cavities. This kicked off decades of research on fluoride for cavity prevention, including whether the fluoride was more effective if given topically on the teeth or systemically.[ref]

The CDC currently recommends 0.7 mg/L of fluoride in drinking water.[ref] Approximately 73% of municipal water systems in the US follow the CDC recommendations and have added fluoride to the water.[ref]

Vitamin D, fluoride, and bones:

I mentioned above that excess, chronic fluoride from drinking lots of tea or water high in fluoride could impact bone health.

Vitamin D is involved in how bones absorb minerals such as calcium – and fluoride. Genetic variants in the vitamin D receptor are linked to an increased risk of skeletal fluorosis in people exposed to a lot of fluoride. (More in the genotype section)[ref]

Related article: Vitamin D Genes

Sodium fluoride was tried as a medication in the 80s and 90s as a way of preventing osteoporosis. However, long-term studies showed that not only did fluoride not prevent osteoporosis, but it may actually make bone density slightly worse.[ref][ref]

Fluoride health effects on thyroid function

Your thyroid needs iodine to synthesize thyroid hormones. Fluorine can impact how well the thyroid functions, which is exacerbated when low iodine intake.[ref]

TSH, a thyroid-stimulating hormone, is often measured to determine whether someone has hypothyroidism or underactive thyroid gland activity. TSH levels above 4.5 mIU/L with normal thyroid (T3, T4) hormone levels usually indicate hypothyroidism. Some researchers consider TSH levels above 2.5 mIU/L as increasing the risk of subclinical hypothyroidism, which affects 5-10% of the population.[ref]

A recent study in Canada found that higher fluoride exposure is linked to thyroid dysfunction only in people who were also iodine deficient. There was no link between fluoride levels and higher TSH levels with adequate iodine. About 18% of the study participants were iodine deficient.[ref]

Related article: Genes related to thyroid hormone production

Sperm count and reproductive effects:

Animal studies show that high fluoride levels can impact sperm motility, and a study in the 1990s in India showed that higher fluoride exposure correlated with slightly decreased testosterone levels.

A recent study looked at men grouped by lower fluoride exposure (2-13mg/day) and higher fluoride exposure (up to 27mg/day). A decrease was seen in the sensitivity of FSH response to inhibin-B in the high fluoride group. However, none of the semen parameters were altered in the high fluoride group. The study concluded: “The results obtained indicate that a fluoride exposure of 3–27 mg/day induces a subclinical reproductive effect that can be explained by a fluoride-induced toxic effect in both Sertoli cells and gonadotrophs.”[ref]

Related article: Male Infertility and Genetics

Soft tissue calcification:

Fluoride can be incorporated into various tissues in the body, causing calcification. The question, in my mind, is whether this is relevant at levels that humans are chronically exposed to. Only about 1% of absorbed fluoride is stored in soft tissue.[ref]

In animal studies, higher chronic fluoride exposure increased calcification in the aorta (heart).[ref]

For people living in an area with high fluoride in the water, an x-ray study found that 89% showed “calcification and/or ossification of the attachments of ligaments, tendons, muscles, and interosseous membranes.”[ref]

Whether fluoride causes soft tissue calcification isn’t clear cut and likely involves several variables. For example, in an animal study with a higher ratio of phosphorus to calcium than normal, the addition of fluoride reduced calcification in the kidneys.[ref]

Intelligence:

Higher fluoride levels in the water are a problem for developing children, especially in countries with both agricultural runoff and naturally higher fluoride mineral levels. China is one country that has studied the effects of higher water fluoride levels fairly extensively.

On average, children exposed to higher fluoride in their water have slightly lower IQs. This is a problem of serious concern in areas of China and India with higher groundwater fluoride concentrations.[ref]

Fluoride causes neurotoxicity in the brain by interfering with the activity of several metabolic enzymes. It can inhibit brain glucose utilization and affect mitochondrial function in the neurons. Additionally, animal studies clearly show that higher fluoride levels cause neurotoxicity.[ref]

A study of ~1,000 children in China divided the participants into two groups called high intelligence (>120) and non-high intelligence (70-120). The average fluoride exposure of the high-intelligence group was 0.7 mg/l of water, while the non-high-intelligence group had an average of 1 mg/l of fluoride in their water.[ref] To be clear: the fluoride in the water for the ‘non-high intelligence’ group is above the range of what is added to fluoridated municipal supplies in the US and Canada.

Genetics plays a role in whether high fluoride in the water is more likely to cause decreased IQ levels. Genetic variants in the dopamine receptors and enzymes related to dopamine breakdown are linked to decreased IQ with high fluoride exposure.[ref] (More in the genotype report)

Related article: Genetics and IQ

Degenerative Eye Diseases:

Fluoride exposure also contributes to degenerative eye diseases like cataracts and macular degeneration.

A 2019 study found that fluoride exposure is a risk factor for cataracts and macular degeneration, and it also elucidated the mechanism of action. The researchers found that fluoride impacts enzymes and genes related to mitochondrial energy as well as reactive oxygen species and oxidative stress (e.g., Nrf2, glutathione, NF-kB, heat shock proteins).[ref]

Mast cell activation from fluoride:

An older study in animals states: “Calcium triggers the secretion of histamine from mast cells after previous exposure to sodium fluoride.”[ref] Other animal studies back up the link between mast cell degranulation, histamine release, and fluoride exposure[ref][ref], especially in the presence of N-acetylcysteine.[ref]

However, I’m not finding any studies that elaborate on the amount of fluoride needed to cause mast cell degranulation in humans.

Lifehacks: Natural Ways to Decrease Fluoride Intake

You’ll need to weigh the pros and cons of fluoride for yourself, considering the benefits of cavity prevention and the long-term effects of higher fluoride exposure. The solutions below are geared towards reducing systemic fluoride exposure and facilitating detoxification.

The rest of this article is for Genetic Lifehacks members only.  Consider joining today to see the rest of this article.

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