2025: Exploring the Impacts of Fluoride-Induced Thyroid Toxicity: A Comprehensive Review

[pfpcnews]

Patial B, Thakur R - "Exploring the Impacts of Fluoride-Induced Thyroid Toxicity: A Comprehensive Review" Biol Trace Elem Res. 2025 Oct 11. doi: 10.1007/s12011-025-04840-6. Epub ahead of print.
https://link.springer.com/article/10.10 ... 25-04840-6

Abstract

Fluoride exposure via contaminated drinking water is a significant global public health concern. Fluoride being beneficial at minimal concentrations was used for dental caries prevention, but excessive exposure of fluoride has been associated with numerous health disorders including skeletal and dental fluorosis, weakening of bones making them more prone to fractures, impaired intelligence, stunted growth, reduced birth and fertility rates, and disruption of thyroid function. This review provides a concise overview of all the existing literature on the effects of fluoride on the thyroid gland till date. Various data collection methods including PubMed, Scopus, ResearchGate, and Google Scholar were used to collect relevant research papers using keywords "changes caused by fluoride in thyroid" or "fluoride induced toxicity on the thyroid gland" ranging from 1976 till date. Fluoride adversely affects thyroid function via interfering with iodine metabolism (replacing iodine in the gland and also inhibiting its uptake). It also disrupts T3 and T4 production causing decrease in their levels, increased TSH, oxidative stress, and downregulated antioxidant and thyroid-related genes. Histopathological alterations caused by fluoride includes thyroid follicular cell apoptosis, necrosis, and hyperplasia of thyroid gland. Thyroid gland, in particular, is highly susceptible to fluoride accumulation, making it one of the most affected organs. Numerous studies have evaluated the impact of fluoride on mammalian models, with a focus on endocrine system particularly the thyroid gland. Fluoride exposure can lead to hypothyroidism, particularly detrimental during fetal and early developmental stages affecting IQ, brain, and hearing development.

[admin]

Here we have yet another review full of errors, misunderstandings, and false citations, apparently with no effective peer review.

Here are a few of the most clearly false claims in the paper - and they don't even deal with the thyroid...

- Fluoride levels below 0.5 mg/L cause dental cavities.

- 0.5–1.5 mg/L are good for dental health, while 1.5–4 mg/L cause dental fluorosis.

etc.

The authors cite references that do not support the statements made. For example, they cite a Zoeller paper [ref #57]to support the following:

• Histopathological damage in rats treated with fluoride includes flattened follicular epithelia and reduced colloid and hyperplasia in the thyroid gland, which results in increased organ weight [55, [57], 67].

  Various studies have reported decreases in T3 and T4 levels, thyroid peroxidase activity (TPO), Na+/K+-ATPase activity, and increased TSH levels in fluoride-exposed rats [57, 64–68].

  Numerous studies on rats and mice exposed to fluoride have reported decreased serum T3, T4, and TPO with elevated TSH, decreased activities of antioxidant enzymes (SOD, CAT, GST, GPx), and histopathological alterations in thyroid follicular cells, including flattened follicular epithelia, ill-defined basal membrane, low colloid content, cytoplasmic vacuoles, loss of mitochondria, irregularly shaped nuclei, vacuolization in the epithelial lining, necrosis, apoptosis, thyroid calcification, and hyperplasia [57, 64, 65, 69, 71, 84–86].

  Previous studies have reported decreased T3 and T4 with elevated TSH in fluoride-treated rats [51, 64, 65, 67–69, 81, 90], which might result from degeneration of thyroid follicular cells and inhibited iodine absorption, leading to impaired thyroid function because thyroid function depends on iodine availability [57, 66, 69, 85].

  Fluoride readily displaces iodine in the body because it is chemically more active than iodine; it binds to iodine receptors on the thyroid gland, inhibits Na+/K+-ATPase activity, and decreases the iodine level in the gland [57, 58].

The problem is that Zoeller’s paper [57] has nothing to do with fluoride. It is titled “Environmental Chemicals Impacting the Thyroid: Targets and Consequences,” and it does not mention fluoride at all, let alone report fluoride studies in rats.

• Zoeller RT - "Environmental Chemicals Impacting the Thyroid: Targets and Consequences" Thyroid 17(9):811-817 (2007)
  https://doi.org/10.1089/thy.2007.0107

Throughout the paper, claims are paired with citations that do not support them. There are references in tables that do not match the studies discussed.

They claim to focus on the thyroid itself, yet they show no understanding of the basic mechanisms of fluoride effects on thyroid function. They talk about “receptor-level iodine displacement” and “iodine receptors,” which do not exist.

Example:

Fluoride binds to iodine receptors on the thyroid gland, inhibits the Na/K-ATPase activity, and decreases the iodine level in the gland.

The paper does not mention the effects of fluoride on deiodinases at all, despite this being the primary mechanism affecting thyroid hormone metabolism and documented since the 1950s. The word “deiodinase” appears only in the glossary.

The review is unusable. It duplicates set pieces from elsewhere, reuses canned language, and shows no grasp of what is being discussed.

It is amazing that reviews like this even make it to print.