Foods with high iodine content are seafood, such as kelp, laver, fresh hairtail, dried clam, scallop, mussel, sea cucumber, jellyfish and lobster. The iodine content in kelp is the highest, reaching more than 24 mg/kg in dried kelp, followed by 8 μ g/kg in shellfish and fresh marine fish. However, the iodine content in salt is very small, and the more refined the salt, the less iodine it contains, and the iodine content in sea salt is about 2 μ g/kg.

8%-9% of human iodine comes from food, 1%-2% from drinking water, and 5% from air. Therefore, iodine in food is the main source of human iodine. Iodide in food can be absorbed only after it is reduced to iodine ions, and iodine combined with amino acids can be absorbed directly. On land, the iodine content of eggs and milk is as high as 4 μ g/kg ~ 9 μ g/kg, followed by meat. The iodine content of freshwater fish is lower than that of meat, and the iodine content of plants is the lowest, especially fruits and vegetables.