The low iodine diet is a special diet that limits the amount of iodine you can consume through foods and beverages. This article gives an overview of the thyroid gland, RAIU scans, RAI treatment, which foods to avoid and include on a low-iodine diet, and overcoming challenges of the diet.
Overview
Iodine is a trace mineral or element found in some foods, some types of salt, and dietary supplements. It does not naturally occur in the body so it needs to come from these foods or supplements.
The thyroid gland uses dietary iodine to produce thyroid hormones that regulate metabolism. Thyroid cells are unique because they are the only cells in the body that absorb iodine. Too little or too much iodine can cause or worsen thyroid disease.
A low-iodine diet is necessary when preparing for a radioactive iodine uptake (RAIU) test or treatment. This diet is required “starve” the thyroid of iodine and reduce the amount of resident iodine. Lowering amounts of resident iodine makes the thyroid “iodine hungry.”
When it’s time for the RAIU scan or treatment, you will take radioactive iodine (RAI) in capsule form. RAI uptake into the thyroid cells allows them to be visualized on a diagnostic imaging scan. It can also destroy tumor cells when this therapy is used for thyroid cancer treatment.
The low iodine diet may sound simple because you only need to eliminate one mineral from your diet—iodine. But it requires some planning. If you eat a lot of pre-packaged or frozen foods or eat out, you will need to make some significant adjustments while on a diet.
The Thyroid Cancer Survivors Association provides recommendations regarding which foods are permitted and prohibited when following a low iodine diet. This organization is considered a trustworthy and knowledgeable source of information.
Foods to Avoid
Most low-iodine diets take less than 50 micrograms (mcg) of iodine per day. However, it’s best to ask your healthcare provider to ensure you don’t have a different requirement. The following have higher levels of iodine and should be avoided while on a low-iodine diet:
Dairy (milk, yogurt, cheese, butter, ice cream, sour cream)Egg yolksSeafood (anything from the ocean, including fish, shellfish, and kelp)Processed foods (pre-packaged foods, frozen dinners, deli meats, hot dogs, bacon, sausage, foods at restaurants and fast-food eateries)Commercial baked goods (commercially baked bread and confections)Soy (includes soybeans, soy sauce, tofu, and any other food with soy)Maraschino cherriesChocolate (milk chocolate contains dairy; some dark chocolates may be allowed—check the label)Red dye #3 (check the label or call the manufacturer)Beans (avoid red kidney beans, navy beans, lima beans, pinto beans, and cowpeas)
Foods to Include
Don’t be disheartened by the list of foods you cannot eat! There are plenty of foods you can eat. Here are foods that are allowed on the low-iodine diet:
Fresh meats (no more than 5-6 ounces a day)Fresh fruits and vegetables (no potato skins)Frozen vegetables without added salt (no rhubarb)Vegetable oilsSodas (as long as they don’t contain red dye #3; check the label or call the manufacturer)Unsalted peanut butter and nutsCoffee and tea (non-dairy creamer is allowed)Matzo (check the label to make sure there is no iodate dough conditioner)Homemade bread (without egg yolks, dairy, or iodized salt in the ingredients)Fresh and dried herbs and spices, including pepperBeer, wine, and distilled alcohols (wine coolers and flavored liquors may contain red dye #3, check the label)Canned peaches, pineapple, and pearsHoneyMaple syrupJams and jelly (without red dye #3)
Challenges
Among the challenges of following a low iodine diet is that you may find conflicting information about which foods are allowed and prohibited on the diet. One source may say that you should only avoid potato skins, while another may suggest that you cannot eat potatoes at all.
Foods higher in iodine:
Bread with iodate: Two slices of bread made with iodate dough conditioner - 320 micrograms (mcg)Cod: Three ounces of baked cod - 158 mcgSeaweed: Two tablespood of nori seaweed - 116 mcgOysters: Three ounces of cooked oysters - 93 mcgYogurt: 3/4 cup of plain greek, nonfat yogurt - 87 mcgIodized salt: 1/4 teaspoon - 76 mcgEggs: One large hard-boiled egg - 26 mcgCheese: 1 ounce cheddar cheese - 15 mcg
Apple juice: 1 cup apple juice - 1 mcgRice: 3/4 cup brown cooked rice - 1 mcgSea salt (non iodized) - 1/4 teaspoon - less than 1 mcgCorn: 1/2 cup canned - 0 mcgBroccoli: 1/2 cup boiled - 0 mcgBanana: Large banana - 0 mcgPasta: 1 cup enriched pasta boiled without iodized salt - 0 mcg
Confusing information can add to the challenge of this already restrictive diet. Don’t hesitate to ask your healthcare provider for a referral to a nutritionist if you want personalized advice and guidance.
Dining Out
Eating out is almost nearly impossible while following a low-iodine diet. You can’t guarantee what type of salt a restaurant uses in their recipes. Foods served in fast food restaurants are mostly processed and contain salt, so they should be avoided as well.
Buy non-iodized salt (replace all of your salt shakers with it)Use olive oil to replace butter or margarineMake fresh oil and vinegar dressingStock up on pasta and frozen vegetables (don’t use iodized salt to boil pasta or cook vegatables)Keep natural peanut butter, jam, and honey on handBake or buy bread without iodate dough conditioner (matzo is a good choice, be sure to check the label)Shop the outer perimeter of the grocery store (fresh fruits, veggies, and meat)Limit meat to six ounces per day
Recipes and Cookbooks
When you season your food and cook at home, be sure to use non-iodized salt or kosher salt instead of iodized salt. Try using fresh herbs such as basil or cilantro to liven up your meals. You can prepare a variety of foods as long as the ingredients fit the criteria above.
Cooking can be challenging, even if you are already a good cook because it is hard to learn a new way of preparing food. The Thyroid Cancer Survivors Association offers a low-iodine cookbook that can be downloaded for free. It boasts over 300 low-iodine recipes and is a favorite among low-iodine dieters.
Summary
The low iodine diet is a special diet that limits the amount of iodine you can consume through foods and beverages. It’s often used before diagnostic radioactive iodine uptake (RAIU) tests and before radioactive iodine treatments.
Breakfast:
Orange juice, oatmeal, coffeeOne slice of toast (use bread without iodate dough conditioner) with natural jam or honey, cream of wheat, fresh fruit
Lunch:
Fresh beef or turkey (up to six ounces per day), pasta (cooked with non-iodized salt), green beans, an apple, and graham crackersHomemade vegetable soup and a salad with homemade oil and vinegar dressing
Dinner:
Salad with homemade oil and vinegar dressing, fresh meat (up to six ounces per day), broccoli, fresh fruitPasta (no iodized salt) sauteed with olive oil and vinegar, fresh basil and tomatoes, non-iodized salt, and pepper
Low-iodine diets are necessary before these tests or treatments to “starve” the thyroid of iodine so the radioactive iodine (in capsule form) can get into the thyroid or thyroid cancer tissue more easily.
In addition to switching to non-iodized salt, those on a low-iodine diet should avoid foods such as bread with iodate dough conditioner, seafood, seaweed, processed foods, dairy, and more. When preparing to go on a low-iodine diet, it helps to prepare by stocking up on foods you can eat such as fresh vegetables and fruit.
A Word From Verywell
Following a new diet can feel overwhelming and frustrating. We’ve included some tips and example meal plans to help get you started. Contact your healthcare provider if you need extra guidance. They may be able refer you to a nutritionist or provide you with more direction.
