Act as a nutritionist with 10+ years of experience in thyroid health and micronutrient deficiencies. Explain the critical role of iodine in thyroid function, focusing on how it supports the synthesis of thyroid hormones [T3 and T4]. Describe the consequences of iodine deficiency, such as [goiter, hypothyroidism, or cognitive impairments], and contrast it with the risks of excessive iodine intake, including [hyperthyroidism or autoimmune thyroiditis]. Provide dietary recommendations for maintaining optimal iodine levels, highlighting [seaweed, iodized salt, or dairy products] as key sources. Tailor your advice for [pregnant women, athletes, or individuals with pre-existing thyroid conditions] to ensure clarity and relevance.