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.

Salt is a common source of iodine. But, low iodine has nothing to do with sodium, which is also found in salt. While you are on your low-iodine diet, sodium is fine, as long as it’s from other sources.

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.

Recap

Foods and certain medications may contain iodine. When following a low-iodine diet, be sure to read labels carefully and check in with your doctor if you have any questions.

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

  • Non-iodized saltFresh, canned, and frozen vegetables in cooked or raw formUnprocessed meats, including beef, pork, and poultryPasta and riceSome breadMatzoEgg whitesFruitsUnsalted nutsUnsalted nut butters such as peanut butter and almond butterPopcorn with non-iodized saltDark, non-dairy chocolateIodine-free spicesVegetable 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.

There are many foods you can eat on a low-iodine diet. Keep in mind that finding low-iodine friendly prepared foods from a restaurant or bakery may be a bit tricky. You may want to prepare your own food during this time just to be safe.

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.

Frequently Asked Questions

  • What are the side effects of a low-iodine diet?
  • There are no negative effects of eating low-iodine food. The recommendations for the diet used to treat hypertension, or high blood pressure, are similar to the recommendations for a low-iodine diet, so you may see your blood pressure and cholesterol levels improve.
  • Learn More:
  • Benefits of the DASH diet
  • What are some low-iodine diet snacks?
  • Your best options are fresh fruits and vegetables, but other recommendations include:Dried fruitApplesauceUnsalted nutsUnsalted peanut butter and rice cakesMatzoh or other unsalted crackersFruit juiceHomemade muffins
  • Learn More:
  • Where to Watch for Hidden Salt with Iodine
  • Which foods have iodine?
  • Only a small number of foods have iodine naturally occurring in them. These include seaweed, some fish, and dairy. Most dietary iodine comes from foods that have iodine added, especially iodized salt, seasonings, commercial baked goods, and other processed foods.
  • Learn More:
  • Why You Need Iodine

There are no negative effects of eating low-iodine food. The recommendations for the diet used to treat hypertension, or high blood pressure, are similar to the recommendations for a low-iodine diet, so you may see your blood pressure and cholesterol levels improve.

Your best options are fresh fruits and vegetables, but other recommendations include:

Only a small number of foods have iodine naturally occurring in them. These include seaweed, some fish, and dairy. Most dietary iodine comes from foods that have iodine added, especially iodized salt, seasonings, commercial baked goods, and other processed foods.