The Iosat Potassium Iodide tablet functions by filling the thyroid with suitable iodine, therefore, blocking absorption of cancer-causing iodine released from a nuclear bomb or nuclear reactor. Some types of iodide help thyroid gland function well. People get iodide from foods like fish and iodized salt. The thyroid can hold only a given amount of iodine. Radiation iodine released in the air may get in the thyroid gland and harm it.