China has a policy of universal iodization, and in order to prevent iodine deficiency diseases, it is mandatory for the state to add a small amount of iodized salt to the edible sodium chloride table salt. Iodized salt is table salt containing sodium chloride (NaCl) with potassium iodate (KIO3). Some people with hyperthyroidism, when they cannot buy non-iodized salt and need a low iodine diet, resort to heating iodized salt to make the iodine evaporate and thus reduce the iodine content. Is this effective? In the past, iodized salt was made by mixing potassium iodide with table salt, which is easily oxidized in the air and volatilized after heating. Since 1989, China has not added potassium iodide to table salt, but potassium iodate (KIO 3). Potassium iodate is a strong oxidizing agent and will not be oxidized in air or light; moreover, potassium iodate is an ionic crystal with a high boiling point and is not volatile, so it will not evaporate when heated and fried or when salt is added early. Some popular science articles emphasize that iodized salt should be kept away from light and that cooking with iodized salt should not be done early or late, but in fact they are referring to potassium iodide. How much iodine is contained in iodized salt? Currently, according to the National Food Safety Standard “Iodine Content of Edible Salt” (GB26878-2011) issued by the Ministry of Health of China on September 15, 2011, each province chooses one of the following three standards for the average value of salt iodine content according to local conditions: 20 mg/kg, 25 mg/kg, 30 mg/kg. For example, Shandong Province adopts the level of 25 mg/kg ± 30%. So how much iodized salt is enough to eat? For example, in Shandong province, one gram of iodized salt contains 25 micrograms of iodine according to the provincial standard, and generally 150 micrograms of iodine per day for adults is enough, so if you eat 6 grams of iodized salt per day, it is enough for iodine supplementation.