The Truth About Thyroid Supplements: What You Need to Know
The supplement industry is largely non-evidence-based and often wastes people’s money. While I occasionally recommend supplements for specific conditions such as Vitamin D, Magnesium, Zinc, Iron, and sometimes B6 or Omega-3, there are certain supplements I never recommend—especially those marketed for thyroid health. Ironically, these supplements can often worsen thyroid function.
The Problem with Thyroid Supplements
Thyroid supplements typically contain high amounts of iodine. While iodine is a critical nutrient for thyroid hormone production, too much iodine can cause problems. High doses of iodine can trigger a phenomenon known as the “Wolff-Chaikoff effect,” a regulatory mechanism that prevents hyperthyroidism by inhibiting thyroid hormone production. This effect usually lasts for 10-14 days and is sometimes used as a treatment for severe hyperthyroidism before surgery.
However, some people experience a “failure to escape from the Wolff-Chaikoff effect,” leading to long-term or permanent hypothyroidism. This is more common in individuals with underlying Hashimoto’s disease. I’ve had patients who were treated by their naturopath with high-dose iodine supplements for a TSH of 4-6, only to become profoundly hypothyroid.
Risks of High-Dose Iodine
High-dose iodine can also cause significant hyperthyroidism, especially in individuals with a large thyroid or goitre. Outside of pregnancy, there isn’t evidence supporting the treatment of asymptomatic mild sub-clinical hypothyroidism. Many patients likely wouldn’t have had any thyroid issues if they hadn’t started taking these supplements.
Recommended Iodine Intake
The daily recommended dietary intake (RDI) of iodine is 150mcg. Some thyroid supplements contain twice this amount! I recommend using iodised salt and consuming store-bought bread, which should provide sufficient iodine for most people, especially non-vegans/vegetarians. More is not always better when it comes to vitamins and minerals. Always check with your doctor before taking supplements, especially if you have any underlying health conditions.