CLAIM:
Using fluoride toothpaste daily can lead to thyroid problems by interfering with iodine absorption. The reel suggests that excessive fluoride exposure may disrupt thyroid function, particularly in women, and that these issues can be reversed through simple dietary changes without medication.
FACT:
There is no strong scientific evidence that using fluoride toothpaste causes thyroid problems or interferes with iodine absorption. Research shows any thyroid effects are linked to very high fluoride exposure, mainly from drinking water—not normal toothpaste use. Experts say that claims suggesting thyroid disorders can be reversed through diet alone are misleading, as many conditions require proper medical treatment.
In a viral Instagram reel posted by dietician Ramanjot Kaur, concerns have been raised about a possible link between everyday toothpaste use and rising thyroid problems, particularly among women. The video suggests that a common daily habit, brushing teeth, may be contributing to hormonal imbalances through fluoride exposure.
In the reel, it is claimed that the increasing number of thyroid cases could be linked to people “literally eating fluoride every day,” illustrated using the example of toothpaste. The video frames fluoride as a hidden risk factor that may be interfering with normal thyroid function.
What does research say?
Large population studies find no evidence linking everyday fluoride exposure, including toothpaste use, to thyroid disorders. While very high fluoride levels, mainly from drinking water, may affect thyroid hormones, current evidence remains mixed and inconclusive.
A 2017 population-based study using data from the Canadian Health Measures Survey examined whether fluoride exposure was associated with thyroid conditions or hormone levels. The researchers found that “there was no evidence of a relationship between fluoride exposure… and the diagnosis of a thyroid condition,” and “no statistically significant association between fluoride exposure and abnormal… TSH levels.” The study concluded that, at a population level, fluoride exposure from sources including drinking water and dental products was not associated with impaired thyroid functioning.
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At the same time, some research suggests that very high levels of fluoride exposure may have an impact on thyroid health. A 2024 systematic review analysing multiple human studies found that while low levels of fluoride exposure showed no effect, “hormone levels started to linearly increase around 2.5 mg/L” of fluoride in drinking water. The review noted that “high fluoride exposure has been associated with abnormal thyroid function,” including increased TSH and reduced T3 and T4 levels, particularly in areas with elevated fluoride in water.
Importantly, the review also highlights that drinking water and diet are the primary sources of fluoride intake, with only minimal exposure occurring from accidental ingestion of dental products. This distinction is critical when evaluating claims about toothpaste.
The NHS also echoes this balanced view. It explains that the thyroid gland is essential for growth and development and that “iodine is an important nutrient for making thyroid hormones.” While fluoride plays a beneficial role in dental health, “fluoride, when used at low concentration, has beneficial effects, but excessive exposure to fluoride for a long time may affect human health.” The NHS further notes that although “some previous studies have suggested that fluoride may compete with iodine,” the current evidence for this interaction remains unclear.
What experts recommend?
Dr Mahesh D M, Senior Consultant – Endocrinology, Aster CMI Hospital, Bangalore, said there is no strong scientific evidence to support the claim that normal use of fluoride toothpaste interferes with iodine absorption or causes thyroid problems. He explained that the amount of fluoride in toothpaste is very small and most of it is spat out, so it does not enter the body in significant amounts.
“Thyroid disruption is more likely seen only in cases of very high fluoride exposure, such as contaminated drinking water, not from daily oral hygiene practices,” he said, adding that fluoride from toothpaste has not been proven to block iodine absorption in real-life conditions.
He further explained that fluoride affects thyroid hormones only at relatively high exposure levels, usually much higher than what people get from toothpaste. “The small amount of fluoride in toothpaste is considered safe and only minimal traces may be ingested accidentally, which are far below harmful levels,” he said.
On treatment, Dr Mahesh said thyroid disorders cannot always be reversed through diet alone. He explained that while mild cases linked to nutrient deficiencies may improve with diet, many common thyroid conditions require medical treatment. “Diet can support thyroid health, but it is usually not enough to fully reverse the disorder on its own,” he added.
Agreeing to this, Dr Minal Meshram, Endocrinologist, Apollo Spectra Hospital, Mumbai, said that relying only on diet is not sufficient for managing thyroid disorders. “Only eating a well-balanced diet will not improve thyroid health. Prompt treatment is necessary based on the problem, like hypothyroidism or hyperthyroidism,” she said. She further advised, “Don’t take any medication on your own and follow the expert’s advice.”
This story is done in collaboration with First Check, which is the health journalism vertical of DataLEADS
