In recent years, the media has reported that thyroid cancer has become the fastest growing malignant tumor in Beijing, with the incidence rate increasing 2.25 times in ten years. The incidence rate of thyroid cancer in China has also risen from the 15th to the 5th place among cancers. Such a rapid increase has led people to point the finger at iodized salt. Is the high incidence of thyroid cancer due to iodized salt? Thyroxine has physiological functions such as promoting metabolism, body development and brain development. Thyroid cancer is a common malignant tumor of the head and neck, accounting for about 1% of all cancers. Through clinical observation, it is 2 to 3 times more common in young and middle-aged women than in men. The causative factors of thyroid cancer are uncertain. As with many other tumors, the pathogenesis of thyroid cancer is still difficult to determine. Therefore, the inference that there is a link between the increased incidence of thyroid cancer and salt iodization is not well founded and lacks sufficient evidence. Radiation, iodine overdose, genetic inheritance, adverse emotions, and hormone levels may all contribute to the development of thyroid cancer. However, there is no direct evidence that iodine overdose can cause thyroid cancer. Experts do not agree with the approach of replacing iodized salt with seafood for many people who are “afraid of iodized salt”, “The iodine content of common seafood (except kelp) is very small and far from the normal physiological iodine requirement of human body. Some statistics show that if you eat seafood to supplement iodine, you need to eat 750 grams of seafood a day to meet the amount of iodine needed for the day. However, how can the average person eat that much seafood in a day?” Both iodine excess and iodine deficiency are harmful. Is there really an increase in thyroid cancer patients? On the one hand, due to the lack of a standardized tumor disease registration system in China, we usually borrow the incidence data from foreign countries for reference, which does not accurately reflect the real incidence situation in China. On the other hand, thyroid cancer is a relatively common disease of low malignancy, and more and more people are found to have thyroid cancer at an early stage, which may be related to the popularization of the application of color ultrasound technology, the improvement of the examination level of ultrasonographers and the improvement of the accuracy and sensitivity of the instruments. Therefore, even if there is an increase in the number of cases, it is not entirely due to the increase in the number of people who have the disease now. As for the concern about the danger of iodine excess, both iodine excess and iodine deficiency are harmful. The definition of iodine excess (urinary iodine greater than 300 μg/L) was first proposed by an international authoritative academic organization in 2001, which concluded that iodine excess may lead to a significant increase in the incidence of hypothyroidism, impaired brain development, autoimmune thyroid disease and papillary thyroid cancer. Iodine intake should vary from person to person to achieve a reasonable intake Human iodine intake should vary from person to person to achieve a reasonable intake. Normal people should avoid the two extremes of not consuming iodine at all and consuming large amounts of iodine. For example, people living in northern China should pay more attention to iodine intake in their daily life to avoid “great neck disease” because the iodine content in water is very low. People in coastal cities, on the other hand, can reduce their iodine intake because their environment and food are not deficient in iodine. Pregnant women need to consume more iodine-containing foods during pregnancy, as iodine plays an important role in the development of the thyroid cells of the fetus in the womb, which is related to the future intellectual development of the child.