Effects of Combined Iodinated Casein and Selenomethionine Supplementation on Thyroid Function and Immune Regulation in Hypothyroid Rats

Hypothyroidism, characterized by insufficient thyroid hormone production, is frequently associated with iodine deficiency. Selenium is essential for thyroid hormone metabolism and immune regulation. This study examined the effects of iodinated casein and selenomethionine supplementation on thyroid function and immune-inflammatory markers in a rat model of hypothyroidism. Thirty-six male Wistar rats were divided into four groups: control, hypothyroid (induced by thyrozol), hypothyroid rats treated with iodinated casein and selenomethionine, and hypothyroid rats treated with iodinated casein only. After 10 days of supplementation, serum levels of thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), calcitonin, and cytokines (IL-6, TNF-α, IL-10, IFN-γ) were assessed. Compared to the controls, the hypothyroid group showed elevated TSH levels, decreased T3 and T4 levels, and a pro-inflammatory cytokine profile. Treatment with both iodinated casein and selenomethionine improved TSH levels, partially restored T3 and T4 levels, and normalized cytokine levels, whereas iodinated casein alone was less effective. Calcitonin levels remained unchanged after combined supplementation. These findings suggest that supplementation with both micronutrients is more effective than iodine alone in restoring thyroid hormone balance and modulating immune responses in individuals with hypothyroidism.