What is low-iodine diet?

What is a low-iodine diet for thyroid cancer treatment?

Your doctor may put you on a low-iodine diet before treating you with radioactive iodine. If you are on a low-iodine diet, you cannot eat foods that contain a lot of iodine, such as iodized salt, seafood, and baked goods. Depleting your body of iodine may make radioactive iodine treatment more effective, because your cells become "hungry" for iodine.

Foods to avoid for a low-iodine diet include milk and other dairy products, commercial baked products (including most breads), seafood, and red food dye #3. A low-iodine diet is not the same as a low-salt diet. Most salt in the United States and Canada has iodine added, so low-iodine diets avoid iodized salt, but non-iodized salt is okay to eat.

For more information, talk to your doctor or a registered dietitian, or visit the Thyroid Cancer Survivor's Association website at www.thyca.org/rai.htm.

Why is a low-iodine diet used?

A low-iodine diet helps prepare your thyroid gland for a radioactive iodine test or treatment. Your thyroid gland holds most of the iodine in your body. With a low-iodine diet, the amount of iodine in your body goes down. This helps the cells in your thyroid pick up radioactive iodine better during your procedure.

How do you follow a low-iodine diet?

Your doctor may put you on a low-iodine diet for 1 to 2 weeks before your treatment or test. You might continue the diet for a couple of days afterward. Your doctor will give you instructions about what foods to avoid and for how long.

In some cases, you may just avoid vitamins or other supplements. These products often contain small amounts of iodine. In other cases, you may get a list of foods to avoid.

Foods to avoid include:

  • Iodized salt.
  • Processed, canned, dried, salted, or cured meats and poultry. These include deli meats, bacon, sausage, and hot dogs.
  • Nuts and seeds prepared with iodized salt.
  • Milk and other dairy foods.
  • Milk chocolate and any chocolate foods that contain milk.
  • Whole eggs and egg yolks.
  • Store-bought grain products like bread, tortillas, and egg noodles.
  • Seafood and all seafood products, including shellfish and imitation crab.
  • Seaweed, kelp, and any other sea vegetables.
  • Foods, drinks, and medicines that contain the food dye FD&C Red No. 3 (erythrosine).

Foods that are okay to eat include:

  • Fresh meat and poultry.
  • Egg whites.
  • Potatoes and rice.
  • Homemade breads, cakes, desserts, and tortillas made without iodized salt or high-iodine ingredients like dairy or eggs.
  • Fresh or frozen vegetables.
  • Dried peas and lentils.
  • Fresh or frozen fruits and fruit juices.
  • Unsalted nuts and seeds.
  • Dark chocolate.

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