A systematic analysis on possibility of water fluoridation causing hypothyroidism

Indian J Dent Res. 2018 May-Jun;29(3):358-363. doi: 10.4103/ijdr.IJDR_505_16.


Background: Community water fluoridation is widely used worldwide and its role in preventive dental health care is well established. However, there is sufficient evidence of the ill effects of excessive fluoride content in water, causing skeletal and dental fluorosis. Alongside, there was also extraskeletal and dental manifestations of excessive fluorides reported. They include the effect on thyroid function, but the literature regarding this is sparse.

Aim: The present systematic review aims to analyze the data from controlled studies about the effect of fluoride on thyroid function.

Materials and methods: A systematic literature search was performed using PUBMED, MEDLINE, EMBASE, COCHRANE Library, EBSCO search, and the internet search, with language restriction to English. The search included published studies which dealt with the association of fluorine with hypothyroidism, from January 1981 to November 2015. Literature search was done using keywords: fluoride and hypothyroidism, dental fluorosis and thyroid disorders, systemic fluorosis and thyroid disease, excessive water fluoridation and hypothyroidism, thyroid and fluoride, fluorosis and its adverse effects.

Results: Out of 166 publications, related to search strategy, 37 full articles which were related with the association of fluoride and hypothyroidism were acquired for further inspection. Out of the 37 articles, 10 articles met the inclusion criteria. The data were extracted and placed in an excel sheet and were analyzed. The analysis suggested a positive correlation of excess fluoride and hypothyroidism.

Conclusion: The present systematic review suggests a positive correlation between excess fluoride and hypothyroidism. This calls the need for further well-controlled studies in this otherwise emerging alarming issue. It also calls for considerable community network through health informatics for problem sensitization.

Keywords: Hypothyroidism; systematic analysis; water fluoridation.

Publication types

  • Systematic Review

MeSH terms

  • Fluoridation / adverse effects*
  • Humans
  • Hypothyroidism / chemically induced*
  • Risk Factors