Understanding a Low-Iodine Diet

If you are being treated for thyroid cancer, your healthcare provider may tell you to follow a low-iodine diet. You’ll need to be on this diet for about 2 weeks before you have radioactive iodine (RAI) therapy. It will help the RAI treatment work better.

What is a low-iodine diet?

A low-iodine diet means you need to limit the amount of iodine you consume. You need to stay away from foods high in iodine and eat more foods low in it.

Iodine is a chemical found naturally in some foods. It may also be added to some foods during food production. Your body needs some iodine. It helps your thyroid work the right way. Your thyroid makes hormones that help control your body’s breathing, temperature, and metabolism.

Why might you need to follow a low-iodine diet?

You may need be on this diet if you have had surgery to remove thyroid cancer and you are now going to have RAI treatment. RAI treatment helps kill any leftover cancer cells in your body. It may also kill normal thyroid cells.

During treatment, you swallow a pill that has RAI in it. Any normal thyroid or cancer cells in your body will absorb the RAI. The radiation will then kill these cells. Being on a low-iodine diet before treatment will help your body better take in the RAI.

How do you follow a low-iodine diet?

When you are on a low-iodine diet, you need to stay away from foods high in iodine. Reading food labels can help you make the right food choices.

Don’t eat these foods:

  • Iodized salt or foods that have it in them

  • Milk or other dairy products such as cheese, butter, and milk chocolate products

  • Fish and other seafood

  • Kelp and other types of seaweed

  • Egg yolks and foods with whole eggs in them

  • Vitamins and herbal supplements that have iodine

  • Foods with red dye #3 in them, such as maraschino cherries

  • Foods with the additives carrageen, agar-agar, alginate, or nori

While on this diet, you can still eat many other foods, such as:

  • Non-iodized salt or sea salt and foods made with it

  • Egg whites

  • Fresh fruits and vegetables

  • Grains, cereals, and pasta made without high-iodine ingredients

  • Baked goods not made with iodine-containing ingredients, such as salt or butter

  • Unsalted nuts and nut butters

  • Soda, fruit juices, beer, and wine

  • Coffee and tea without creamer or milk

  • Limited amounts of beef and poultry

Talk with your healthcare provider about your medicines. Some may have iodine in them. But, don't stop taking medicines with iodine unless your doctors tells you to. Also ask your healthcare provider about soy products. These don’t have iodine in them. But they may weaken RAI treatment. While on this diet, it’s also a good idea to not eat out at restaurants. It can be hard to know for sure if a restaurant uses non-iodized salt or other iodine-containing ingredients.

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