The main mistake when taking iodine. Why is iodine not absorbed?

The biochemical connection between iodine and selenium in the endocrine system — is one of the key examples of how the deficiency of one micronutrient blocks the function of another.

Iodine itself — is the raw material for the synthesis of thyroid hormones (thyroxine T4 and triiodothyronine T3). But for iodine in these hormones to work, and for T4 to be converted into active T3, selenium-dependent enzymes — deiodinases (iodothyronine deiodinases) — are needed.

Without selenium:

• T4 remains in its inactive form and is not converted into T3.
• Accumulation of T4 without normal conversion can cause symptoms of hypothyroidism, despite normal iodine levels.
• Taking iodine without correcting selenium may increase oxidative stress in the thyroid gland, as selenium is involved in the function of glutathione peroxidase — an antioxidant enzyme that protects the gland's tissue from damage by peroxides.

If there is little selenium in the body, and a person starts taking iodine:

• The thyroid gland receives additional stimulation for hormone synthesis.
• At the same time, antioxidant protection enzymes (glutathione peroxidase, thioredoxin reductase) do not work at full capacity.
• The risk of inflammatory reactions and autoimmune processes (including Hashimoto's thyroiditis) increases.

The correct strategy:

1. First, replenish selenium — usually in the form of selenomethionine or sodium selenite, to a physiological or optimal dosage (often 100–200 mcg per day).
2. Only after that introduce iodine — starting with small doses and gradually increasing to the optimal level (for example, 150–300 mcg per day, if there are no contraindications).