You’ve met with your doctor and you are scheduled for imaging, ablation, and/or therapy in a few weeks and your doctor wants you to follow a low-iodine diet before then. RadioIodine Therapy--What To Expect Why do I need to follow a low-iodine diet? A low-iodine diet is recommended because the thyroid naturally absorbs iodine from food. If you have a diet high in iodine then this could interfere with the results of your treatment which uses a radioactive pill that also contains iodine (that’s how we able able to see thyroid tissue). Typically you follow a low-iodine diet for 1-2 weeks to be absolutely sure that any thyroid tissue in your body is starving for iodine by the time you receive the radioactive iodine. It is important note that iodine is used in contrast material for computer tomography or CT scans, if you recently had that, then you may have to postpone receiving radioactive iodine for 2-3 few weeks. Non-contrast CTs are ok