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Iodine is a key mineral that has many roles in your body.

It’s found naturally in foods like eggs, seafood, and meats and commonly present in the Western diet, as it’s found in iodized salt.

Although iodine is important for your health, dietary iodine may need to be restricted sometimes, such as prior to radioactive iodine therapy for people with thyroid cancer. This is when a low iodine diet may be prescribed.

This article explains what a low iodine diet is, including its benefits and precautions, and provides an overview of foods to eat and a sample meal plan.

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What is a low iodine diet?

Iodine is an essential mineral that plays various roles in your body.

Your thyroid gland uses it to produce thyroid hormones, which aid many important processes. This includes regulating your metabolism and aiding growth and tissue repair (1).

Iodine is present in many foods, such as dairy products, seafood, grains, and eggs.

Though iodine is important, it may need to be restricted in some cases.

A low iodine diet is a short-term diet that may be prescribed to people prior to radioactive iodine therapy for conditions like papillary or follicular thyroid cancer (2).

As part of this diet, people are required to restrict their daily iodine intake to fewer than 50 mcg of iodine per day, which is one-third of the daily allowance of 150 mcg (3).

This short-term diet lasts approximately 1–2 weeks prior to receiving radioiodine and is continued for another 1–2 days afterward. However, these recommendations can vary and depend on your healthcare provider’s professional opinion (3).

The purpose of a low iodine diet is to deplete your body’s iodine stores, which helps improve the effectiveness of the radioactive iodine scan or treatment (3).

A low iodine diet is a short-term diet commonly prescribed to people with thyroid cancer prior to receiving radioactive iodine therapy. Its purpose is to improve the treatment’s effectiveness.

Effects and precautions

The main goal of a low iodine diet is to improve radioactive iodine therapy.

However, this diet may benefit your health in several other ways.

May reduce blood pressure

As a side effect, a low iodine diet may help lower your blood pressure.

This is because the diet restricts many unhealthy food groups, such as processed meats and highly processed snack foods. These particular food groups are restricted because they’re often high in iodized salt.

Numerous studies have shown that consuming a diet high in processed foods is linked to a greater risk of high blood pressure. Additionally, reducing processed food intake in favor of whole foods has been linked to reduced blood pressure (4, 5, 6, 7).

However, it’s important to note that the low iodine diet is temporary. As such, to achieve long-lasting changes in blood pressure, you should minimize your processed food intake over the long term.

May improve diet quality

Additionally, a low iodine diet may help improve diet quality.

This is because many unhealthy foods are very high in iodized salt.

This mostly applies to fast food, frozen meals, and prepackaged items like chips, which are not only typically high in iodized salt but also unhealthy fats and calories.

Because these foods are off-limits in this diet, it may improve your overall diet quality.

However, while a low iodine diet eliminates these foods temporarily, it’s up to you to continue to make healthier food choices moving forward as part of a healthy lifestyle.

Precautions and concerns

While a low iodine diet has its potential benefits, it’s not for everyone.

A low iodine diet is a short-term diet for people who will undergo radioactive iodine therapy. As a short-term diet, it should only be followed for 1–2 weeks prior to therapy and several days afterward, as advised by your healthcare provider.

Due to its restrictive nature, a low iodine diet should not be followed for longer than the advised time period, as it restricts several nutrients. Following it for longer than this time period may raise your risk of nutritional deficiencies.

If you don’t require radioactive iodine therapy and are wanting to try a low iodine diet for other health purposes, there are many other healthy diets you could try instead.

A low iodine diet may benefit your health in several ways, such as improving your blood pressure and diet quality. However, it’s a short-term diet, and to achieve long-lasting changes, you should maintain healthy eating habits after completing the diet.

Foods to eat

Although a low iodine diet is restrictive, it allows for plenty of healthy food options.

Here’s a list of foods you can eat on a low iodine diet (8):

• Fruits: all, except rhubarb and maraschino cherries
• Vegetables: all, raw or frozen (excluding frozen peas) — without salt
• Meats: all fresh meats, up to 6 ounces (170 grams) per day — meats contain some naturally occurring iodine, so excess intake isn’t advised
• Eggs: egg whites only
• Cereals and grains: oatmeal (excluding prepackaged or instant oatmeal), rice, quinoa, couscous, cornmeal, bulgur, buckwheat, plain wheat pasta or other salt-free pasta varieties
• Crackers: salt-free varieties of matzo crackers, unsalted rice cakes, unsalted rice crackers
• Nuts: all nuts, unsalted only
• Baked goods: salt-free breads, homemade breads or homemade baked goods — baked without iodized salt, eggs, and butter (use oil instead)
• Spreads: unsalted nut butters, jams, jellies, honey
• Oils: all vegetable oils, including soy oils
• Beverages: brewed coffee and tea, water, fruit juices
• Herbs and spices: all fresh or dried herbs and spices, non-iodized salt, and non-iodized kosher salt

In addition, your daily intake of allowed meats should be limited to no more than 6 ounces (170 grams), as meats naturally contain iodine.

If you’re unsure whether a food item is allowed on the low iodine diet, you can check its ingredient list to see if it contains salt. Iodine is not typically on most food labels, so if salt is added, it’s most likely iodized salt.

A low iodine diet allows plenty of healthy food groups, including all fresh vegetables, fresh meats (excluding seafood), cereals and grains, homemade breads and baked goods, and all fresh herbs and spices.

Foods to avoid

Many people may find the restrictive nature of a low iodine diet challenging.

It eliminates many food groups temporarily, as many foods either contain iodine or enhance the absorption of iodine, such as soy-based foods.

Here’s a list of foods to avoid on a low iodine diet (8):

• Seafood and seafood products: all fish, shellfish, all canned fish (including canned tuna), seaweed, all sushi, and any foods made with fish stock
• All processed or cured meats: including luncheon meats, bacon, hot dogs, smoked meats, salami, corned beef, canned poultry, and more
• Organ meats: all organ meats, including liver, heart, and more
• Eggs: whole eggs or egg yolks (egg whites are fine)
• Certain fruits and vegetables: including canned, fresh, or dried beans and lentils, frozen peas, instant mashed potatoes, canned soups with beans or lentils, seaweed, rhubarb, and maraschino cherries
• Soy foods: including tofu, edamame beans, soy sauce, soy-based meats, and more
• Dairy products: all, including milk products, such as yogurt, cheese, milk (more than 1 ounce or 30 mL per day), butter, cream, and more
• Baked goods: including commercially baked products and homemade baked goods containing dairy products, such as milk and butter
• Desserts and sweets: all dairy-based sweets, such as chocolate, commercially baked products, pudding, and blackstrap molasses
• Condiments and spreads: including all nut butters (excluding unsalted varieties), barbecue or hot sauces, sauces of Asian origin, such as oyster, fish, and soy sauce
• Snack foods: including all salted nuts, processed snack foods, such as chips and pretzels
• Seasonings: including iodized table salt, seasoning mixes with iodized salt, alternative salts, such as onion salt, gravies containing milk or butter, bouillon cubes, stock broth, and other soup bases, and more
• Certain supplements: including vitamin and mineral supplements that contain iodine, cough syrups with Red Dye No. 3, all nutritional supplements containing iodine, and herbal supplements.
• Beverages: including milk, soy milk, and fruit punch or commercial drinks that contain Red Dye No. 3
• Certain additives: all foods containing Red Dye No. 3, carrageenan, agar-agar, algin, and alginates

It’s worth noting that foods containing Red Dye No. 3, such as maraschino cherries, should be restricted because this additive contains iodine.

It’s also best to avoid eating out or purchasing takeaway food while on a low iodine diet, as it’s very difficult to determine which restaurants use high iodine ingredients.

A low iodine diet restricts many common foods, such as seafood, processed or cured meats, whole eggs and egg yolks, dairy products, commercial baked goods, and many snack foods, among others.

A low iodine sample 1-week menu

Designing a low-iodine-diet-friendly menu can be challenging due to limited options.

To help you get started, here is a 1-week sample menu that’s low in iodine.

Monday

Breakfast: oatmeal with berries

• rolled oats (not instant or prepackaged)
• 1/4 cup (31 grams) of fresh berries of your choice
• water, per your desired oatmeal consistency

Lunch: roasted chicken sandwich

• 2 slices of homemade or low iodine bread
• 3 ounces (85 grams) of roasted chicken
• fresh vegetables of your choice, such as lettuce, tomatoes, carrots

Dinner: roasted chicken pasta

• 3 ounces (85 grams) of roasted chicken
• 4 ounces (115 grams) of whole wheat pasta, cooked
• spinach and bell peppers, cooked
• a drizzle of olive oil

Tuesday

Breakfast: egg white omelet with veggies

• 3 egg whites
• fresh or frozen vegetables of your choice from the allowed list
• a pinch of black pepper and non-iodized kosher salt

Lunch: roasted chicken salad dressed in olive oil

• 3 ounces (85 grams) of roasted chicken (use leftovers)
• fresh salad with spinach, avocado, tomatoes, and red onions.
• a drizzle of olive oil

Dinner: soft-shelled tacos

• 3 ounces (85 grams) of ground beef or other meat
• seasonings of your choice, such as cumin, oregano, and garlic powder
• homemade soft shell tacos (use non-iodized salt)

Wednesday

Breakfast: avocado-cucumber-tomato toast

• 2 slices of homemade or low iodine bread
• avocado, spread and mashed
• sliced cucumbers and tomatoes for a garnish

Lunch: quinoa salad

• cooked quinoa
• vegetables, such as spinach, cucumber, avocado, tomatoes, and onions
• a drizzle of olive oil and lemon juice

Dinner: roasted lamb with roasted vegetables

• 3 ounces (85 grams) of roasted lamb (you can roast more for leftovers)
• roasted vegetables of your choice, such as potatoes, carrots, and broccoli

Thursday

Breakfast: oatmeal with berries

• rolled oats (not instant or prepackaged)
• 1/4 cup (31 grams) of fresh berries of your choice
• water, per your desired oatmeal consistency

Lunch: roasted lamb wrap

• 3 ounces (85 grams) of roasted lamb (leftovers from dinner)
• 1–2 homemade or low iodine tortillas
• fresh vegetables of your choice, such as lettuce, avocado, and tomatoes

Dinner: roasted chicken with steamed vegetables

• 3 ounces (85 grams) of roasted chicken (you can roast more for leftovers)
• steamed vegetables, such as potatoes, beans, broccoli, and carrots

Friday

Breakfast: egg white omelet with veggies

• 3 egg whites
• fresh or frozen vegetables of your choice from the allowed list
• a pinch of black pepper and non-iodized kosher salt

Lunch: leftovers from Thursday’s dinner

• 3 ounces (85 grams) of roasted chicken
• steamed vegetables, such as potatoes, beans, broccoli, and carrots

Dinner: chicken wraps

• 3 ounces (85 grams) of chicken, cooked in any way you prefer
• 1–2 homemade or low iodine tortillas
• fresh vegetables of your choice, such as lettuce, avocado, and tomatoes

Saturday

Breakfast: scrambled egg whites with toast

• 4 egg whites
• 2 slices of homemade bread or low iodine bread
• a pinch of black pepper and non-iodized kosher salt

Lunch: stuffed sweet potatoes

• 1 sweet potato, baked
• up to 3 ounces (85 grams) of roasted chicken (you can use leftovers)
• a handful of spinach
• a handful of fresh cranberries

Dinner: roasted beef with roast vegetables

• 3 ounces (85 grams) of beef, roasted
• roasted vegetables of your choice, such as potatoes, carrots, and broccoli

Sunday

Breakfast: banana-berry smoothie

• 1 cup (240 mL) of coconut milk
• 1/4 cup (31 grams) of blueberries
• 1 banana

Lunch: roast beef salad

• 3 ounces (85 grams) of roast beef (use leftovers)
• fresh salad with spinach, avocado, tomatoes, and red onions
• a drizzle of olive oil

Dinner: grilled pork tenderloin with roasted veggies

• 3 ounces (85 grams) of grilled pork tenderloin
• roasted vegetables of your choice, such as potatoes, carrots, and broccoli

A low iodine diet has plenty of options for a healthy and delicious menu. The section above provides a sample low iodine menu for 1 week.

The bottom line

A low iodine diet is often prescribed to people with thyroid cancer to improve the effectiveness of their upcoming radioactive iodine treatment.

This short-term diet is very restrictive and typically followed for 1–2 weeks prior to therapy and continued for a few days afterward. However, the exact guidelines can vary by individual and depend on your healthcare provider.

Though this diet is restrictive, there are plenty of healthy food options and meal ideas to consider, such as the ones provided in the sample menu above.