Longevity | Biohacking | Strength on Instagram: "Here’s what the evidence actually says. Fluoride does not “swap into” thyroid hormone in place of iodine. Thyroid hormones (T4/T3) literally contain iodine atoms, and fluoride is not incorporated into that structure the way the claim implies. But fluoride can still interact with thyroid biology in other ways, especially at higher exposures. The most plausible mechanism in the literature is interference with iodine handling (for example, effects on