Whether it’s through your drinking water or toothpaste, you’re likely exposed to fluoride multiple times each day. Despite the decades of research demonstrating the benefits of fluoride for dental health, fluoride remains a controversial mineral that some experts claim should be avoided due to its possible adverse health risks. Continue reading to learn about the benefits of fluoride as well as some of the potential risks associated with its consumption.
What is fluoride?
Fluoride, the ionic form of fluorine, is a naturally occurring mineral found in soil, air, food, water, and supplements. (13) Fluoride is found in small amounts in many foods and beverages. Beverages and foods with fluoride include:
- Bottled and municipal water with added fluoride
- Coffee and tea
- Some canned foods (e.g., fruits, anchovies, shrimp) (10)(13)
Fluoride is most commonly used in dental care products, such as toothpastes and mouthwashes, to strengthen the outer layer of the teeth, known as the enamel, and to prevent dental caries (cavities), damaged areas of the teeth that develop into tiny openings or holes. Individuals who are prone to cavities may be advised by their dentist to use a toothpaste or other dental care products containing fluoride. Furthermore, dentist offices also provide topical fluoride preparations for cavity prone individuals. (13)
Did you know? About 99% of fluoride in the body is found in the bones and teeth. In adults, approximately 50% of fluoride in the gastrointestinal tract is retained and the other 50% is excreted in urine. Children retain up to 80% of absorbed fluoride. (13)
Fluoride in water
Water fluoridation, the process of adding fluoride to community water sources, is regarded as one of the most successful public health measures of the 20th century. Multiple major health organizations, including the American Dental Association, American Academy of Pediatrics, U.S. Public Health Service, and World Health Organization, recommend water fluoridation for preventing cavities in the public. (5)
To minimize the risk of fluoride toxicity while also preventing cavities, the U.S. Public Health Service recommends that concentrations of fluoride in drinking water be 0.7 mg/L. The upper tolerable limit for fluoride (maximum amount of daily fluoride that can be taken without risk of serious side effects) is estimated to be 0.12 mg per kilogram of body weight per day, or approximately 5 mg per day for nine to 14-year-olds and 7 mg per day for individuals 15 and older. (3) The Environmental Protection Agency (EPA) determined that the maximum allowable concentration of fluoride in public drinking water systems is 4 mg/L. (13)
Water fluoridation is common in North America; however, some controversy exists over the addition of fluoride to public water sources. For example, doses cannot be controlled considering that each individual consumes varying amounts of water and foods containing fluoride per day. (3) Some have also raised ethical concerns over water fluoridation given that fluoride is added to a city’s water supply without the informed consent of its citizens. (6)
Did you know? If you are concerned about the levels of fluoride in your city’s drinking water supply, you can purchase a specialized water filter called a reverse osmosis system to eliminate fluoride. (9)
What does fluoride do for teeth?
Fluoride has been known to prevent tooth decay since researchers first discovered its benefits in the late 19th and early 20th centuries. (10) Fluoride also helps prevent early cavities from progressing by remineralizing the teeth. (17) Several studies investigating the benefits of fluoride toothpastes conclude that fluoride effectively reduces the number of cavities in children and adults alike. (8)(10)(13) In fact, as a result of fluorination of water and availability of fluoride dental care products, the incidence of dental cavities has significantly declined in developed nations. (16) Research demonstrates that self-applied or professionally-applied topical fluoride provides the best effects versus fluoride found in water or supplements. (2)
What causes dental cavities? When bacteria in the mouth metabolize sugars, they produce lactic acid, thus decreasing the pH of saliva. If the pH falls below pH 5.5, the enamel can begin to demineralize, allowing cavities to form. (10)
Health concerns of fluoride
When consumed in quantities that exceed the recommended daily tolerable upper intake levels, fluoride poses some health risks. Furthermore, certain populations may be more sensitive to fluoride-related adverse effects, and therefore may be advised to reduce their exposure.
Although fluoride provides many benefits to dental health, too much fluoride can lead to a cosmetic condition known as dental fluorosis, which is characterized by white lines or flecks, or white or brown stains on the teeth. In severe cases, dental fluorosis can progress to pitting in tooth enamel. Typical, everyday use of fluoride is unlikely to cause severe dental fluorosis and the risk of this condition increases when intake exceeds the recommended daily amount. (13)
Did you know? According to data collected by the National Health and Nutrition Examination Survey (NHANES) between 1999 and 2004, over 22% of individuals between the ages of six and 49 had dental fluorosis; however, less than 1% had severe fluorosis. (4)
High doses of fluoride can cause certain gastrointestinal symptoms such as diarrhea, nausea, vomiting, and abdominal pain. These side effects are rare and typically occur when high doses of fluoride are unintentionally consumed, such as in situations when an individual unintentionally ingests topical fluoride products used in a dentists’ office or when fluoride supplements are used inappropriately. In even rarer situations, excessive levels of fluoride in water can cause gastrointestinal upset. (13)
Did you know? Fluoride toxicity is rare in adults. Over 80% of fluoride toxicity cases, often a result of ingestion of fluoride-containing dental care products, are seen in children younger than six. (3)
Delays in cognitive development
Some evidence suggests that exposure to fluoride during gestation and early development may increase a child’s risk of cognitive impairments and lower intelligence quotient (IQ) scores. (19) A systematic review of 149 human studies, 339 experimental animal studies, and 60 in vitro studies concluded that high fluoride exposure is linked to cognitive impairment in children; however, due to inconclusive and inadequate research, the same conclusion can not be drawn for adults. (18) It’s important to note that this systematic review is still in draft form and is currently undergoing peer review. Some organizations, such as the National Academies of Sciences Engineering and Medicine (NASEM), raised concerns about this draft, suggesting that it doesn’t provide convincing evidence to support the argument that “fluoride is presumed to be a cognitive neurodevelopmental hazard to humans.” (14)
Recent research has raised concern over the potential effects of fluoride exposure on thyroid function. One study found that thyroid stimulating hormone (TSH) values are higher among individuals whose water has a higher fluoride concentration, suggesting impairment of thyroid function. (11) Another study published in 2020 concluded that low-moderate fluoride exposure is associated with changes in childhood thyroid function. (20)
In contrast, a study evaluating the urinary fluoride levels among Canadians found no association between high levels of urinary fluoride levels and elevated TSH levels or reduced thyroid function. Interestingly, the study noted that fluoride and iodine, a trace mineral found in seafood, seaweed (nori), and some fortified foods, may interact with one another through various mechanisms, and iodine deficiency may instead be the cause of reduced thyroid function. In fact, iodine-deficient individuals evaluated in this study tended to be exposed to lower water fluoride concentrations, but they had higher urinary fluoride concentrations compared to participants who were not iodine deficient. Fluoride may interfere with certain mechanisms necessary for proper thyroid function, which can worsen adverse effects on the thyroid gland in iodine deficient individuals. (12)
In summary, fluoride exposure may impair thyroid functioning among individuals with moderate-to-severe iodine deficiencies; however, individuals with normal iodine stores appear less susceptible to these negative effects and adequate iodine intake may mitigate these effects. (12)
Hydroxyapatite: an alternative to fluoride?
Hydroxyapatite, a calcium phosphate mineral, is an ingredient included in some dental care products and may be an alternative to fluoride. A 2019 demonstrated that 10% hydroxyapatite toothpaste prevented demineralization and remineralized initial cavities similarly to fluoride toothpaste. If you’re concerned about the adverse effects of fluoride, speak to your integrative healthcare provider and dentist regarding suitable alternatives. (1)
The bottom line
Fluoride has long been used to promote healthy teeth by preventing dental decay. Some research suggests that fluoride, particularly when consumed in large amounts, may pose some health risks. More research is needed to determine the potential health implications of fluoride.
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- American Dental Association. (2021). Fluoride: Topical and systemic supplements. https://www.ada.org/resources/research/science-and-research-institute/oral-health-topics/fluoride-topical-and-systemic-supplements#:~:text=Fluoride%20can%20be%20delivered%20topically%20and%20systemically.,-1%2C%203&text=1%2C%203-,Topical%20fluorides%20strengthen%20teeth%20already%20present%20in%20the,making%20them%20more%20decay%20resistant.&text=Topical%20fluorides%20encourage%20remineralization%20of,the%20growth%20of%20plaque%20bacteria
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- Beltrán-Aguilar, E. D., Barker, L., & Dye, B. A. (2010). Prevalence and severity of dental fluorosis in the United States, 1999-2004. NCHS Data Brief, (53), 1–8.
- Centers for Disease Control and Prevention. (2020). Community water fluoridation. https://www.cdc.gov/fluoridation/index.html
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- dos Santos, A. P., Nadanovsky, P., & de Oliveira, B. H. (2013). A systematic review and meta-analysis of the effects of fluoride toothpastes on the prevention of dental caries in the primary dentition of preschool children. Community Dentistry and Oral Epidemiology, 41(1), 1–12. https://doi.org/10.1111/j.1600-0528.2012.00708.x
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- Jaafari-Ashkavandi, Z., & Kheirmand, M. (2013). Effect of home-used water purifier on fluoride concentration of drinking water in southern Iran. Dental Research Journal, 10(4), 489–492.
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- National Institutes of Health. (2022). Fluoride. https://ods.od.nih.gov/factsheets/Fluoride-HealthProfessional/
- Ontario Academy of General Dentistry. (2021). NASEM strongly recommends revisions to NTP’s second draft monograph on fluoride exposure hazards. https://www.agd.org/constituent/news/2021/02/18/nasem-strongly-recommends-revisions-to-ntp-s-second-draft-monograph-on-fluoride-exposure-hazards
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