A low iodine diet (LID) is a temporary, medically-supervised eating plan designed to limit the amount of iodine in your body. This is most often required for patients preparing for radioactive iodine (RAI) treatment for thyroid cancer. By lowering your body's iodine levels, the treatment becomes more effective, as the thyroid gland and any remaining thyroid cancer cells will be more receptive to absorbing the radioactive iodine. The diet typically lasts for one to two weeks before the treatment and continues for a few days after. The key is to consume fresh, whole, and unprocessed foods while strictly avoiding high-iodine sources like seafood and dairy products. With careful planning and attention to detail, you can successfully follow this diet for the required duration without sacrificing flavor or nutrition.
What to Eat: Approved Foods on a Low Iodine Diet
Transitioning to a low iodine diet involves focusing on fresh ingredients and cooking meals at home to control the iodine content. Many delicious and nutritious foods are naturally low in iodine and can be enjoyed freely.
Fresh Fruits and Vegetables
Most fresh and frozen fruits and vegetables are excellent choices for a low iodine diet, provided they are not canned with iodized salt or red food dye (like maraschino cherries). Enjoy a wide variety of colorful produce to ensure you are getting a full spectrum of vitamins and minerals. Examples include:
- Fresh or frozen berries, bananas, apples, and peaches
- Potatoes (without the skin, as the skin may contain some iodine), sweet potatoes, and rice
- Onions, garlic, broccoli, spinach (cooked), and carrots
- Canned fruits, such as peaches or pears, are acceptable if packed without red dye.
Proteins
While seafood is prohibited, there are still plenty of low-iodine protein options. It is important to stick to fresh, unprocessed meats and poultry in limited quantities, typically no more than 6 ounces per day, as they contain naturally occurring iodine.
- Fresh, unprocessed meat and poultry: Chicken, beef, pork, lamb, and turkey
- Egg whites: The yolk is high in iodine, but egg whites are a safe protein source.
- Dried beans, peas, and lentils: These are excellent plant-based protein sources. Canned versions should be checked for added salt.
- Unsalted nuts and nut butters: These offer healthy fats and protein.
Grains and Starches
The key to incorporating grains is to choose homemade or unsalted options, as commercial baked goods often contain iodized salt or dairy.
- Homemade bread and baked goods: Use non-iodized salt and oil instead of milk and butter.
- Pasta and rice: Ensure they are plain and cooked without iodized salt.
- Unsalted crackers: Matzo crackers are often a good option.
- Oatmeal and other hot cereals: Choose unsalted, plain varieties.
Fats and Oils
Most vegetable oils and unsalted fats are safe for use on a low iodine diet.
- All vegetable oils, including soy oil
- Unsalted butter or non-dairy spread in limited amounts
- Homemade vinaigrette dressings using oil and vinegar
Sweets, Beverages, and Spices
There are still plenty of ways to add flavor and enjoy simple treats on this diet.
- Sweets: Sugar, honey, jam, jelly, maple syrup, and dark chocolate with over 70% cocoa are acceptable choices.
- Beverages: Brewed coffee, tea (without milk or dairy creamers), fruit juices, and most sodas (check for red dye #3).
- Herbs and Spices: Non-iodized salt, black pepper, and all fresh or dried herbs and spices are allowed for seasoning.
Foods to Avoid on a Low Iodine Diet
To ensure the diet's effectiveness, it is crucial to avoid a specific list of foods that contain high levels of iodine. This is not an exhaustive list, and label reading is always recommended.
Seafood and Sea Products
This is the single largest source of dietary iodine. All fish, shellfish, and sea vegetables must be completely avoided.
- Fish (freshwater fish may be okay, but consult your doctor)
- Shellfish (shrimp, crab, lobster, oysters)
- Seaweed and sea products (kelp, nori, kombu, carrageenan, agar-agar)
Dairy Products and Eggs
Dairy products are a major source of iodine in the Western diet, primarily due to iodine-containing disinfectants used on dairy farms and in feed supplements.
- Milk, cheese, yogurt, ice cream, butter, and whey protein
- Egg yolks and products containing whole eggs, like fresh pasta or custard
- Milk chocolate
Iodized Salt and Processed Foods
Most commercially prepared and processed foods contain iodized salt. Always check the ingredients list for salt, and specifically avoid products containing iodized salt.
- Iodized table salt or sea salt (unless specifically non-iodized and approved)
- Cured or processed meats (bacon, sausage, deli meats)
- Most commercial breads and baked goods
- Many canned foods and sauces
Soy Products
While soy itself is not inherently high in iodine, some studies suggest it may interfere with radioactive iodine uptake. Many physicians recommend avoiding all soy products.
- Soy milk, tofu, soy sauce, edamame
Certain Food Dyes and Supplements
- FD&C Red Dye #3: Avoid products containing this food dye, such as maraschino cherries.
- Vitamins and Supplements: Many multivitamins and supplements contain iodine. Consult your doctor about any supplements you take.
Allowed vs. Avoided Foods Comparison
| Food Category | Allowed Foods | Avoided Foods |
|---|---|---|
| Salt | Non-iodized salt, some kosher salt (confirm label) | Iodized salt, sea salt (unless specified non-iodized) |
| Proteins | Fresh, unprocessed meats (limit 6oz/day), egg whites, unsalted nuts/nut butters, dried beans/lentils | Seafood, egg yolks, cured/processed meats, soy products |
| Dairy | Non-dairy alternatives (rice, almond, coconut milk without carrageenan) | Milk, cheese, yogurt, butter, ice cream, milk chocolate |
| Fruits & Veggies | Most fresh/frozen fruits and vegetables (peeled potatoes) | Maraschino cherries, red dye #3, rhubarb, potato skins |
| Grains | Homemade breads, rice, pasta, unsalted oatmeal | Commercial baked goods, boxed cereals with high-iodine ingredients, egg noodles |
| Fats | Vegetable oils, unsalted margarines, homemade vinaigrette | Salted butter, most store-bought dressings |
| Sweets | Sugar, honey, jam, maple syrup, dark chocolate (>70% cocoa) | Milk chocolate, candies with red dye #3 |
| Beverages | Water, black coffee/tea, fruit juice, clear sodas | Cow/soy milk, dairy creamers, red-colored drinks |
Conclusion
Following a low iodine diet is a crucial, though temporary, step in preparing for radioactive iodine treatment. By understanding what to eat on a low iodine diet, focusing on fresh, homemade foods, and carefully reading labels, you can effectively manage your iodine intake. Always prioritize preparing meals at home to control ingredients and avoid hidden sources of iodine in processed foods and restaurant dishes. Remember that this is not a permanent lifestyle change, but a focused and important part of your medical treatment. Consult your healthcare provider or a registered dietitian for personalized advice and support during this time.
Navigating the Low Iodine Diet: Label Reading and Preparation
Successfully following a low iodine diet often depends on your ability to confidently identify and avoid hidden sources of iodine. The primary source is iodized salt, but additives can also be an issue. Always check the ingredient lists on packaged foods and beverages.
Key Ingredients to Check For
- Salt: Check if the ingredient is 'iodized salt'. While non-iodized salt is permissible, the source and type are important. Opt for kosher salt, but verify the label to ensure no iodine is added.
- Dairy: Look for milk, cheese, whey, or casein.
- Sea Products: Avoid products containing kelp, carrageenan, agar-agar, or other sea-derived ingredients.
- Dough Conditioners: Some commercial breads use iodate dough conditioners, so homemade bread is generally safest.
- Red Dye #3: This food coloring (also known as E127) is found in maraschino cherries and some candy and soda.
The Importance of Homemade Meals
Preparing your own food from scratch is the most reliable way to control iodine content. When eating at restaurants or consuming takeout, it is nearly impossible to guarantee that iodized salt, dairy, or other high-iodine ingredients were not used. Planning meals and cooking at home will provide peace of mind and help ensure the diet is followed accurately. Use fresh herbs and spices, vinegar, and non-iodized salt to enhance flavor without increasing iodine. For additional recipes and resources, the ThyCa (Thyroid Cancer Survivors' Association) offers a comprehensive cookbook and guidelines: ThyCa Low-Iodine Cookbook.
The Role of Moderation
Some foods contain a moderate amount of naturally occurring iodine and may be limited rather than completely avoided, such as some animal proteins. Always follow your doctor's specific recommendations, as guidelines can vary slightly depending on your treatment plan. The goal is a low-iodine, not a no-iodine, diet, and complete avoidance is neither necessary nor possible.
