As the incidence of thyroid disease continues to rise, the question of whether or not to consume iodized salt has become a major concern. Some people even point the finger at iodized salt as the culprit for the high incidence of thyroid disease. Iodine is an essential trace element for the human body and is one of the raw materials for the synthesis of thyroid hormones. Insufficient iodine intake can lead to thyroid follicular hyperplasia and increase the incidence of goiter or nodules, and conversely, excessive intake can lead to thyroid diseases such as thyroiditis or thyroid cancer. Therefore, the intake of iodine cannot be generalized or answered in a broad-brush manner. Based on the iodization of salt in China at 35 micrograms/gram and a per capita salt intake of 10 grams per day, our daily intake of iodine is 350 micrograms, which is not higher than the recommended amount of iodine by the World Health Organization after deducting the losses from cooking and human metabolism. Even if we consider the differences between the European and American races and the Chinese physique and moderately lower the standard, the current daily iodine intake in China is still within the acceptable range. Then residents of coastal cities like Shanghai, especially those who usually consume more seafood, have sufficient iodine intake, then there is no need to supplement it by iodized salt, especially for patients with thyroid nodules. However, if you eat less iodine, you are going from one extreme to the other. According to relevant studies, the incidence of thyroid cancer is significantly higher in both iodine-deficient and high-iodine areas than in areas with normal iodine. The level of iodine intake and the type of thyroid cancer pathology are related, with high incidence of follicular carcinoma in iodine-deficient areas and papillary carcinoma in iodine-sufficient areas. Therefore, we recommend scientific iodine supplementation. The simpler way is that those who often eat seafood should try to eat less iodized salt to avoid excessive iodine intake; those who do not eat seafood should not eat exclusively non-iodized salt to avoid insufficient iodine intake.