Iodine is an essential trace element and the main raw material for the synthesis of thyroid hormones by the thyroid gland. Thyroid hormone can improve the metabolic activities of the body, promote physical growth and brain development, and maintain all normal physiological functions of the human body. Iodine in human body mainly relies on daily diet supplement, the ocean is nature’s iodine reservoir, so seafood contains high iodine, the soil and water in highland mountainous areas do not contain enough iodine, if a single intake of land products, it is easy to cause insufficient intake of iodine, the body’s iodine reserve decreases, the body synthesizes less thyroid hormone, the body’s metabolism is insufficient, and growth and development are delayed. Especially for infants and young children, it affects the development of the nervous system and leads to a decline in intelligence. In the past, iodine deficiency diseases such as macrosomia and cretinism were common, but since the national salt iodization was introduced in 1995, the incidence has decreased significantly. In recent years, the incidence of thyroid diseases seems to be increasing again with the popularization of screening methods such as thyroid ultrasound, so we have the question whether it is related to iodized salt. As we all know that the daily iodine requirement for healthy adults is 150μg and 200μg for pregnant women and lactating mothers, excessive iodine intake will also lead to the highest incidence of thyroid disease. Based on the epidemiological findings, and based on the principles of localization, classification and scientific iodine supplementation, China has modified the iodine content of salt three times, with the most recent modification being implemented on March 15, 2012, which reduced the iodine content of iodized salt to 20-30 mg/kg. The most recent modification was introduced on March 15, 2012, and the modification is to reduce the iodine content of iodized salt to 20-30mg/kg. The results of the monitoring and analysis of the iodine nutrition of the population in Zhejiang Province in 2011 showed that the overall iodine nutrition level in the province is at an appropriate level and can be consumed with confidence, but some special groups of people should not be supplemented with iodine, they include: 1. 2. Patients with certain thyroid disorders, such as hyperthyroidism, should not be supplemented with iodine. 3. People who live in areas with severe iodine deficiency for a long time should not take iodine supplementation too high and too fast, otherwise they will have a higher risk of developing iodine hyperthyroidism or other related thyroid diseases. So how should we properly supplement iodine? 1. Recognize the package logo when purchasing: iodized salt must have a package and iodized salt logo. 2. Containing utensils: The utensils for iodized salt should be light-proof bottles or ceramic jars with covers. 3. Placement: Iodized salt should be placed in a cool, dry place to avoid direct sunlight and moisture absorption. 4. Placement time: Iodized salt should not be stored for too long. 5. Usage: When stir-frying, broiling fish or cooking soup, it is advisable to put it in when the food is almost cooked. Do not fry iodized salt in a pan, or fry it in a frying pan.