As we all know, iodine deficiency in adults may lead to “Great Neck Disease”; iodine deficiency in pregnant women may lead to miscarriage, premature birth and stillbirth; iodine deficiency in fetuses may lead to low birth weight, congenital malformation, dementia, dwarfism, deafness and paralysis; iodine deficiency in infants may affect the development of intelligence and various aspects of the body. With so many dangers of iodine deficiency, is it possible to avoid these dangers by taking more iodine supplements? Studies have found that iodine and thyroid disease have a U-shaped relationship, and low or high iodine intake may cause disease. The Chinese Nutrition Society recommends that the safe range of iodine intake is 100-800μg/d, and the recommended amount is 150μg/d for adults and 200μg/d for pregnant women and mothers. Iodine exists widely in nature in the form of iodide in food, air, water and soil, and iodine deficiency diseases are regional in nature and closely related to the local living environment. With the improvement of living conditions and the popularization of salt iodization, iodine deficiency in China has basically been improved, and in some areas, iodine intake is even excessive. Beijing is a suitable city for iodine intake, and the standard for salt iodization is 25mg/kg. With the popularization of ultrasound and other examination techniques, more and more people are detected to be suffering from thyroid disease, so the concern about iodine is increasing, and some people even talk about “iodine”. With the exception of patients with confirmed iodine deficiency, thyroid disorders generally do not require additional iodine supplementation. On the contrary, patients with hyperthyroidism need to limit their iodine intake, try not to eat seafood with high iodine content, and use non-iodized salt as much as possible. Eggs, milk, cereals, meat, beans, vegetables, fruits and freshwater fish are not high in iodine content and can be used normally by patients with thyroid disease.