The Low-Iodine Diet for Radioactive Iodine Treatment

If you are going to have radioactive iodine treatment, which is medication taken by mouth that permanently reduces your thyroid gland activity, you will have to follow a low-iodine diet. Iodine is an element found in food that the body uses to make thyroid hormones.

Following a low-iodine diet for at least two weeks before getting your treatment makes your thyroid more receptive to the medication. This increases its effectiveness. You'll need to continue to maintain this diet until your treatment is complete.

There are a few different thyroid conditions that may be treated with radioactive iodine therapy. These may include several types of thyroid cancer, as well as hyperthyroidism, which occurs when your thyroid makes more hormones than are needed.

This article explains which foods are okay to consume and which foods to avoid when following a low-iodine diet.

What Foods Should I Avoid Before Radioactive Iodine Treatment?

There are certain restrictions when you are on a low-iodine diet. Some foods either contain iodine or increase your absorption of iodine.

Foods you should avoid include:

• Iodized salt
• Dairy products like cheese, cream, yogurt, butter, and ice cream
• Egg yolks, whole eggs, and foods containing whole eggs
• Seafood like fish, shellfish, seaweed, and kelp
• Foods that contain additives like carrageenan, agar-agar, and alginates
• Bread products that contain iodine dough conditioners
• Milk chocolate
• Soy products like soy sauce, soy milk, and tofu
• Any supplements that contain iodine
• Blackstrap molasses
• Cured and corned foods like ham, lox, and corned beef

What Are Some Special Considerations for a Low-iodine Diet?

Medications may be processed with iodine-containing Red Dye #3, or erythrosine. Your healthcare provider or pharmacist can tell you if any of your medications contain iodine. If they do, you may need to change your medication before and while you are receiving your radioactive iodine treatment. Be sure to consult with your doctor before stopping any medicines.

Most commercial vitamin preparations have iodine added as an essential nutrient. Read labels carefully and ensure that you are taking an iodine-free vitamin while following the low-iodine diet.

What Can I Eat on a Low-iodine Diet?

There are many foods that you can eat while on a low-iodine diet. Some may feel concerned about the need to cut out salt, but know that it's fine to use non-iodized salt.

Foods you can eat while on a low-iodine diet include:

• Non-iodized salt
• Fresh, canned, and frozen vegetables in cooked or raw form
• Unprocessed meats, including beef, pork, and poultry
• Pasta and rice
• Some bread
• Matzo
• Egg whites
• Fruits
• Unsalted nuts
• Unsalted nut butters such as peanut butter and almond butter
• Popcorn with non-iodized salt
• Dark, non-dairy chocolate
• Iodine-free spices
• Vegetable oils 
• Soft drinks, coffee, tea, and fruit juices

Can I Have Prepared Foods?

If ordering take-out or eating in a restaurant, be sure to exercise some caution. While some ingredients in a dish may be quite obvious, others—like those in a "special sauce"—may not be. You may be able to request that your food is made without salt or with non-iodized salt. However, you may want to avoid take-out and prepared foods during this time just to be safe.

Keep in mind that baked goods are often made with iodized salt, salted butter, egg yolks, and/or dairy products. Seek out specialty grocery stores and bakeries that sell items prepared with low iodine. Making these items yourself, however, may be easier.

Summary

Before beginning radioactive iodine treatment, you will need to follow a low-iodine diet. While there are some foods that you will need to avoid, there are many food and drink options that adhere to a low-iodine diet. Keep in mind certain medications may also contain iodine and may need to be switched before you begin your treatment.

A Word From Verywell 

Radioactive iodine treatment can be a very effective method of addressing thyroid-related conditions. The process requires some preparation on your part, between following a low-iodine diet and adjusting some of your medications ahead of time. Be sure you are clear on the instructions you need to follow to ensure that you get the most out of your treatment.