The human body needs many elements, among which, trace elements refer to elements accounting for less than 0.01% of the total mass of the organism, and we also refer to trace elements with certain physiological functions and must be taken in through food as essential trace elements. Although the content of these essential trace elements in the body is small, but the role in the process of life activities is very important, can maintain the normal life activities of the body, if the lack of some essential trace elements or trace element imbalance, it will cause disease, and even death. Iodine is one of the essential trace elements. However, when people take in essential trace elements, they tend to focus on the “amount” and ignore the form in which they are taken in, such as the difference between potassium iodide salt and potassium iodate salt. Since 1989, China has not added potassium iodide to table salt, but potassium iodate (KIO3). This is because potassium iodate is a strong oxidizing agent with good stability and will not be oxidized in the air or in the presence of light; moreover, potassium iodate is an ionic crystal with a high boiling point and is not volatile, so there is no need to emphasize adding salt before frying or when serving. However, more and more studies are now showing that potassium iodide is far safer than potassium iodate, which is much more toxic than potassium iodide. Potassium iodate is listed in the Hazardous Chemicals List 2012, and potassium iodate is located in No. 51517, but not potassium iodide. A more visual comparison of the safety of the two can be made in terms of LD50. In toxicology, LD50, or Lethal Dose (50%), is a common indicator to describe the toxicity of toxic substances or radiation, the smaller the LD50 value, the more toxic the exogenous chemical; conversely, the larger the LD50 value, the lower the toxicity. It is obvious that the toxicity of potassium iodate is much greater than that of potassium iodide. Iodized salt is closely related to our daily life, and the primary condition as a food additive is safety. Therefore, when buying iodized salt products, people should see if it is potassium iodide iodized salt to ensure safe consumption, while potassium iodate iodized salt is not recommended for consumption. Second, is iodine supplementation a national campaign? Iodine deficiency can cause iodine deficiency disease, but excessive iodine can also affect the health of the organism. Teng Weiping, a representative of the 9th National People’s Congress, an endocrinologist and vice president of China Medical University, has conducted a two-year research on “iodine nutrition” since 1999, which proved that most Chinese people are not iodine deficient, but iodine overdose, and this has led to an increase in thyroid diseases! In the late 1990s, many students in China suffered from nausea, vomiting, fever, abdominal pain, headache, chest pain and other acute poisoning symptoms due to the use of “iodine nutrition”, which is a clear example. It has been reported that in Hangzhou, the proportion of outpatients with hyperthyroidism increased from 0.9% to 1.47% after consuming iodized salt; in Changzhou, the hospitalization rate of thyroiditis increased by 52.0% after consuming iodized salt; in Fuzhou, Jilin and Dandong, the number of patients with hyperthyroidism increased by 0.3-3.0 times respectively; since the full implementation of iodized salt in Shanghai, endocrinologists “According to another survey and statistical analysis, the incidence of hyperthyroidism in Shanghai has increased significantly compared to the prevalence of iodized salt. The prerequisite for universal iodized salt consumption should be the existence of iodine deficiency in the region, and there is no need to “squeeze in” mass iodine supplementation campaigns in areas that are not iodine deficient. This is because people in different regions and with different diets vary greatly in the amount of iodine they consume from ingredients other than salt. For example, for the hundreds of millions of people living in coastal areas and those who frequently consume seafood such as kelp, they already get enough iodine from ingredients other than salt, and there is no need to get iodine from iodized salt. Third, iodine supplementation can cause men’s health problems? In a study conducted in China with the participation of the Institute of Science and Technology of the National Population and Family Planning Commission and Peking Union Medical College, the effects on the reproductive system of male rats were examined through the intake of different doses of iodine, and it was found that excess iodine may have potentially toxic effects on male reproduction in rats. It is the knowledge of these findings that suggests that men should take care when supplementing with iodine. Iodine is certainly necessary, but the detrimental effects of too much are still little known, and too much iodine may be even more detrimental to men. In conclusion, iodine supplementation in humans is a long-term, daily and living process, and only by consuming iodized salt scientifically can we truly make up for our health. The most natural is also the best.