Fluoride

What does it do? Fluoride appears to have at least two separate mechanisms by which it prevents tooth decay. It affects the demineralization and remineralization of teeth in a way that makes teeth stronger.1 Fluoride also reduces the production of acid by oral bacteria, protecting the teeth from damage.2 Fluoride appears to have both topical and whole-body effects.3

Fluoride is one of few materials known to stimulate osteoblasts, the cells responsible for building new bone.4 While exposure to fluoride clearly causes people to have denser bones, the bone that is formed may not be of optimal quality,5 and may not reduce fracture risk significantly.

Where is it found? Fluoride is a trace mineral found in varying concentrations in foods and in water. Foods high in fluoride include fish, tea, and many different vegetables. Fluoride is added into the municipal water supply of many cities in the United States. For those people without access to fluoridated water, fluoride supplements are available in the forms of tablets and drops. These supplements are not available without a prescription. Many non-prescription dental care products contain fluoride as well, including toothpastes and mouthwashes.

Fluoride has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
3Stars Tooth decay
1Star Osteoporosis
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Who is likely to be deficient? As fluoride is not considered an essential mineral, it does not have an associated deficiency state. Regardless, people living in areas with low concentrations of fluoride in the drinking water do appear to be at a higher risk of significant tooth decay than those living in areas with high amounts of natural or added fluoride.

How much is usually taken? Drinking water containing 1 mg of fluoride per liter is considered to be roughly the optimal amount for the prevention of tooth decay. For those without access to fluoridated drinking water, chewable fluoride tablets containing 0.25 to 1 mg per day of fluoride or fluoride mouthrinses with 0.05% to 0.2% fluoride content can be used. Liquid fluoride drops are also available.

Are there any side effects or interactions? The risks associated with fluoridation of the public water supply have been the subject of vigorous and often heated debate since fluoridation began in 1945. Although much research has been done regarding the safety of fluoridation, a recent review found all prior studies to be of sub-optimal quality and far from definitive.6

Some,7 8 but not all,9 10 studies have found a correlation between the amount of fluoride intake and increased risk of osteoporotic fractures. The validity of the studies that found increased risk of fracture in communities with fluoridated water has been questioned by some scientists.11 A pooled analysis of 29 studies on this issue concluded that there did not appear to be an increased risk of fracture in areas of water fluoridation.12

Dental fluorosis, a brown staining of teeth due to fluoride exposure during childhood, is the best-documented adverse effect of fluoride. At a water fluoride level of 1 part per million (or 1 mg per liter), roughly 13% will have fluorosis to an aesthetically concerning degree.13

Some scientists have concluded that water fluoridation is associated with an increased risk of bone tumors,14 although most others disagree.15

At the time of writing, there were no well-known drug interactions with fluoride.

References:

1. Clarkson BH. Caries prevention-fluoride. Adv Dent Res 1991;5:41–5 [review].

2. Marquis RE. Antimicrobial actions of fluoride for oral bacteria. Can J Microbiol 1995;41:955–64.[review]

3. Ellwood KP, Blinkhorn AS, Davies RM. Fluoride: how to maximize the benefits and minimize the risks. Dent Update 1998;25:365–72 [review].

4. Lau KHW, Baylink DJ. Molecular mechanism of action of fluoride on bone cells. J Bone Miner Res 1998;13:1660–7 [review].

5. Evans FG, Wood JL. Mechanical properties and density of bone in a case of severe endemic fluorosis. Acta Orthop Scand 1976;47:489–95.

6. McDonagh MS, Whiting PF, Wilson PM, et al. Systematic review of water fluoridation. BMJ 2000;321:855–9 [review].

7. Kurttio P, Gustavsson N, Vartiainen T, Pekkanen J. Exposure to natural fluoride in well water and hip fracture: a cohort analysis in Finland. Am J Epidemiol 1999;150:817–24.

8. Danielson C, Lyon JL, Egger M, Goodenough GK. Hip fractures and fluoridation in Utah’s elderly population. JAMA 1992;268:746–8.

9. Hiller S, Cooper C, Kellingray S, et al. Fluoride in drinking water and risk of hip fracture in the UK: a case-control study. Lancet 2000;355:265–9.

10. Phipps KR, Orwoll ES, Mason JD, Cauley JA. Community water fluoridation, bone mineral density, and fractures: prospective study of effects of older women. BMJ 2000;321:860–4.

11. Rosen CJ. Fluoride and fracture: an ecological fallacy. Lancet 2000;355:247–8 [editorial].

12. McDonagh MS, Whiting PF, Wilson PM, et al. Systematic review of water fluoridation. BMJ 2000;321:855–9 [review].

13. McDonagh MS, Whiting PF, Wilson PM, et al. Systematic review of water fluoridation. BMJ 2000;321:855–9.[review]

14. Diesendorf M, Colquhoun J, Spittle BJ, et al. New evidence on fluoridation. Aust NZ J Public Health 1997;21:187–90 [review].

15. McDonagh MS, Whiting PF, Wilson PM, et al. Systematic review of water fluoridation. BMJ 2000;321:855–9 [review].