People whose thyroid cells have mercury in them tend to be older—around 71 years on average—while those without mercury in their thyroid cells are younger, around 50 years old. This doesn’t mean mercury causes aging, but the two seem to show up together.

We analyzed the available evidence and found that people with mercury in their thyroid cells tend to be older, averaging around 71 years, while those without mercury in their thyroid cells are younger, averaging around 50 years [1]. This pattern suggests a connection between the presence of mercury in thyroid tissue and age, but it does not show that mercury causes aging or that aging causes mercury to accumulate. We did not find any studies that contradicted this observation. The evidence we’ve reviewed so far leans toward an association between mercury in thyroid cells and older age, though we cannot say why this link exists. It could be that mercury builds up over time, or that older people have had more exposure to sources of mercury, or that other factors related to aging make the thyroid more likely to retain mercury. We have no data on how mercury gets into the thyroid, how long it stays there, or whether it affects thyroid function. Our current analysis is based on one assertion with 37.0 supporting observations and no refuting evidence, so the picture remains incomplete. What we can say is that if mercury is present in thyroid cells, it’s more common in older individuals — but we don’t yet know what this means for health. If you’re concerned about mercury exposure, reducing intake from high-mercury fish and discussing testing with a healthcare provider may be practical steps.