Thyroid Function Support

Thyroid hormone sets the metabolic rate of nearly every tissue, so even modest deviations show up as fatigue, weight change, cold intolerance, mood disturbance, constipation and cognitive slowing. Because TSH from the pituitary responds to small changes in circulating hormone, it moves before free T4 does and is the earliest usable signal that the axis is under strain. Supporting thyroid function nutritionally means ensuring the raw materials and cofactors are present. Iodine is the substrate — the gland cannot make hormone without it. Selenium is required by the deiodinases that convert T4 into active T3 and by the glutathione peroxidases that protect follicular cells from the peroxide generated during hormone synthesis. Iron is a cofactor for thyroid peroxidase, and low ferritin is a common and underappreciated reason for persistent hypothyroid symptoms despite adequate treatment. Zinc contributes to both conversion and receptor function. The important limit: supplying more of these to someone already replete does not improve thyroid function, and iodine in particular follows a U-shaped curve where excess causes the same dysfunction as deficiency. Nutritional support also cannot substitute for hormone replacement once the gland is failing.

Establish a baseline TSH with free T4 and TPO antibodies before changing anything. Ensure ordinary dietary iodine — dairy, eggs, fish, iodised salt — without supplementing unless a deficiency has been documented, since excess iodine can precipitate dysfunction in autoimmune thyroid disease. Correct low ferritin to above 50 ng/mL and treat vitamin D deficiency; both are common and both drive symptoms that mimic hypothyroidism. In confirmed Hashimoto's, selenium at 200 mcg daily has consistently lowered TPO antibody titres over three to six months in randomised trials, though the effect on thyroid function itself is unproven; keep total intake below 400 mcg. If taking levothyroxine, protect absorption by dosing fasted and separating coffee, calcium, iron and soy by at least four hours. Recheck at 6-8 weeks. Nutritional measures support the axis; they do not replace hormone once the gland is failing.

• •Consistent levothyroxine timing, fasted, 30-60 minutes before food
• •Separate calcium, iron, coffee and soy from thyroid medication by 4 hours
• •Adequate but not excessive iodine from ordinary foods rather than supplements
• •Correct ferritin and vitamin D before escalating thyroid treatment
• •Stop smoking — it worsens Graves' eye disease specifically
• •Adequate sleep and moderate resistance training to support metabolic rate
• •Avoid biotin supplements before testing