Dental Health
Fluoride: Curse or Blessing?
Fluoride strengthens teeth, but high exposure can impair development and thyroid function—children require careful protection.
Dental Health
Fluoride strengthens teeth, but high exposure can impair development and thyroid function—children require careful protection.
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In our modern world, we paradoxically often suffer from our civilisational achievements.
A prime example: civilisation diseases. While presumably 99% of our ancestors struggled with regular food shortages, we suffer from cardiometabolic disorders (obesity and the like) brought on by food abundance.
There are many examples where modern advances bring significant benefits but not without costs to us. In a perfect world, we manage to strike an ideal balance and navigate the trade-offs.
Similarly, one could discuss fluoride.
Fluoride is a term we all know. Fluoride is a mineral that occurs ubiquitously in nature. Therefore, we naturally take it in through food and drinking water. Consequently, like other minerals, it accumulates in our body in certain amounts.
Unlike many other minerals—for example, zinc, iron, and copper—fluoride is not an essential nutrient for humans; that is, it has no biological significance. There are no specific enzymes, proteins, or metabolic processes in the human body that depend on fluoride.
On the other hand, since childhood we have known that fluoride plays a role in dental health. Fluoride deposits in bones and teeth. Particularly in the tooth, it forms robust fluorapatite, which could be described as a kind of « improved tooth enamel ».
This is a central fact: fluoride makes teeth more cavity-resistant via fluorapatite. Everything beyond that becomes … difficult.
Since 2015, fluoride has been tracked as part of the US National Toxicology Program (NTP). Its health effects are continuously examined, particularly regarding developmental neurotoxicity and endocrine disruption.
Here's why:
Meanwhile, additional data suggests negative effects of fluoride on testosterone and oestrogen levels. Specifically regarding intelligence in children, meta-analyses appear to show robust associations between higher fluoride intake and lower IQ.
Furthermore, a recent cross-sectional Japanese study showed that elevated serum fluoride levels in adults are associated with impaired glucose metabolism and reduced insulin secretion, which increases diabetes risk.
Let's be clear: there apparently exists a narrow line between fluoride's cavity prevention benefits and the negative health consequences of excessive exposure.
But how significant is the actual exposure?
Often, studies associate fluoride content in (fluoridated) tap water with health outcomes. Not infrequently, these data are cross-referenced with measured blood and urine values.
First conclusion: the brain appears particularly sensitive to fluoride, with described effects starting around 1–2 mg/l—the thyroid appears to suffer from around 2–4 mg/l.
Here comes good news: tap water in Switzerland is not fluoridated, and most mineral waters don't contain notably high levels. Additionally, there is a labelling requirement for fluoride content in mineral waters above 1.5 mg/l.
Nevertheless, fluoride appears ubiquitously in our lives, for example:
Fluoride-containing toothpaste also significantly contributes to fluoride exposure. In adults, a single application can release more than 0.5 mg of fluoride. However, this amount only becomes health-relevant if the toothpaste is swallowed.
For children, the situation is somewhat more critical. It is estimated that children absorb nearly half of the fluoride contained in toothpaste since they swallow most of it. In children, fluoride-containing toothpaste can therefore significantly contribute to fluoride burden!
But how real are fluoride burdens in practice? This can be assessed reasonably well by looking at the incidence of dental fluorosis. Dental fluorosis is tooth enamel defects that occur with chronically high fluoride exposure in early life (up to approximately 8 years).
From a 2015 letter by the international Fluoride Action Network (FAN), it emerges that the proportion of Americans with dental fluorosis was around 10% in 1940, while for 2011–2012 it had already risen to around 60%.
The incidence of dental fluorosis has risen significantly worldwide in recent decades, likely linked to the major effort to reduce cavity incidence.
In Switzerland, figures may be similar. Since there are no current surveys, it is estimated that up to 15% of the population is affected by dental fluorosis. This is still a significant portion of the population, and the true number is unclear.
There is now robust evidence suggesting that fluoride can have significant negative effects on the body. The main reason fluoride is used widely is cavity prevention.
The primary sources of fluoride exposure are mainly dental treatments—particularly swallowing fluoride-containing toothpaste—and fluoridated tap water. Other significant exposure routes include fluoride-containing mineral waters and fluoridated table salt, which is used in many households.
Fluoride exposure through conventional foods is difficult to control and likely offers no good starting point for reducing exposure.
Our tip: for most people in Switzerland, fluoride will probably not have relevant health significance. Particularly for children, however, the situation is different. Here, parents should be especially careful in their handling of fluoride, particularly in the context of preventative dental measures.
(1) Fluoride Action Network (FAN), 2015. Submission to the National Toxicology Program: Review of fluoride for non-cancer health outcomes, including developmental neurotoxicity and endocrine disruption. Available at: https://ntp.niehs.nih.gov/sites/default/files/ntp/ohat/publiccomms/2015/fan20151106.pdf [Accessed 2 December 2024].
(2) Bai, R., Huang, Y., Wang, F., & Guo, J., 2020. Associations of fluoride exposure with sex steroid hormones among U.S. children and adolescents, NHANES 2013–2016. Environmental Pollution, 260, p.114003. doi: 10.1016/j.envpol.2020.114003.
(3) Taher et al. 2024. Systematic review of epidemiological and toxicological evidence on health effects of fluoride in drinking water. Critical Reviews in Toxicology, 54(1), pp.1–33.
(4) Filippini et al. 2020. Fluoride exposure and cognitive neurodevelopment: Systematic review and dose-response meta-analysis. Environmental Research, 179(Pt A), p.108846.
(5) Itai et al. 2021. Slightly elevated serum ionic fluoride levels inhibit insulin secretion and increase glucose levels in a general Japanese population: a cross-sectional study. Biological Trace Element Research, 199(8), pp.2819–2825.
(6) Iamandii et al. 2024. Does fluoride exposure affect thyroid function? A systematic review and dose-response meta-analysis. Environmental Research, 242, p.117759.
