As we all know, iodine is a trace element in the human body, and it is a necessary raw material for synthesizing thyroid hormones, and iodine plays an extremely important physiological role in the human body. Iodine plays an extremely important physiological role in the human body. Both iodine deficiency and iodine excess can cause harm to the human body. Therefore, it is crucial to promote scientific iodine supplementation. Iodine and thyroid diseases Iodine is the raw material for synthesizing thyroxine, and iodine deficiency can lead to goiter, which can be manifested as diffuse goiter and nodular goiter, or in severe cases, hypothyroidism. Excess iodine can also lead to goiter, but almost always diffuse goiter, iodine intake and goiter is a “U” curve relationship. Therefore, iodine intake in moderation is most beneficial to the human body. High iodine can induce the occurrence of autoimmune thyroid disease, such as Graves’ disease (hyperthyroidism) and “Hashimoto’s disease (often accompanied by hypothyroidism). The incidence of both is significantly higher in areas with high iodine levels. Thyroid nodules are found in both high iodine and low iodine areas. Only high iodine areas are slightly more than low iodine areas. Second, how to correctly treat the relationship between iodine and thyroid disease 1, iodized salt popularity of the pros and cons. Although excessive iodine can lead to “hyperthyroidism”, “hypothyroidism” and an increase in thyroid nodules, after the popularization of iodized salt, the incidence of endemic goiter has been significantly reduced, and the population’s intelligence and physical fitness have been significantly improved. Therefore, universal salt iodization is still a long-term prevention and treatment strategy in China. 2, to avoid going to extremes. In the past, people wrongly called thyroid diseases “thick neck disease”, no matter hyperthyroidism or hypothyroidism, eat more kelp and other high iodine foods, resulting in excessive iodine intake. Recently, more people understand that too much iodine can also lead to thyroid disease, especially in coastal areas with high iodine, many people talk about “iodine” and go to the other extreme – avoiding iodine diet. This is not desirable, low iodine is different from avoiding iodine. Iodine in moderation is the most reasonable. 3, iodine supplementation should be individualized. High iodine diet and low iodine diet can not be a one-size-fits-all, to vary from place to place, from person to person. It should not be dogmatic, but individualized. Even if the same area due to different dietary habits, the same iodine excess and iodine deficiency exists. The city’s different counties and districts in the environment of the iodine content gap is very large, can not be a low iodine diet. There are also goiter caused by iodine deficiency. 4, different thyroid diseases have different requirements for low iodine diet. For example, hyperthyroidism patients should strictly require a low iodine diet. Chronic thyroiditis to low thyroid patients, high iodine diet is wrong, but excessive low iodine diet is not necessary, because no matter low iodine diet or high iodine diet, the patient’s low thyroid more than can not be restored, need lifelong thyroxine replacement therapy. And with the patient’s blood relatives, moderate low iodine diet is very necessary, can prevent the occurrence of thyroid disease. 5, special treatment for special people. For the general population suffering from hyperthyroidism or Hashimoto’s hypothyroidism, a low iodine diet can be required, but pregnant or lactating women suffering from thyroid disease should have an appropriate high iodine diet to satisfy the needs of the fetus or infants. At this time, if the low iodine diet, may lead to the fetus, infants and children goiter, and even affect the development of IQ and height of young children. In short, iodine supplementation should avoid blindness, avoid going to extremes, avoid one-size-fits-all, according to the place, according to the person, according to the disease, according to different periods of time, to follow the principle of individualization, and advocate scientific iodine supplementation!