The reason for requiring a low iodine diet after iodine 131 is to avoid affecting the effectiveness of iodine 131 treatment. A low iodine diet is required after iodine 131 treatment because if iodine-rich foods are consumed, the iodine in the foods will compete with iodine 131 to enter into the thyroid tissue, which in turn will affect the effect of the treatment. Therefore, after iodine 131 treatment, you should avoid eating iodine-rich foods, such as seaweed, nori, hairy vegetables, shrimp, shellfish, crabs, sea fish, etc. You can moderately supplement high-quality proteins, such as milk, eggs, lean meat and so on. Patients undergoing iodine 131 radiation therapy should actively cooperate with the doctor’s treatment and maintain a low iodine diet for a period of time after treatment.