Thyroid cancer patients with papillary or follicular thyroid cancer often receive a dose of radioactive iodine (RAI) about two months after their surgery in an attempt to destroy (ablate) any remaining thyroid cells in their bodies.
Most of these thyroid cancer patients also undergo whole-body radioiodine scans at periodic intervals, using a “tracer” dose of RAI. If their scan is not “clean,” they may then receive treatment with a larger dose of RAI in an attempt to eliminate remaining thyroid cells.
In preparation for an RAI scan or RAI treatment, patients are usually asked to go on a low-iodine diet (LID). The diet is to prepare for the RAI. The patient follows the diet when preparing for RAI either by temporarily stopping levothyroxine (withdrawal) or by receiving injections of Thyrogen (recombinant TSH) while continuing on levothyroxine.
The purpose of a low-iodine diet is to deplete the body of its stores of iodine, to help increase the effectiveness of the radioactive iodine scan or treatment. The premise is that when the radioactive iodine is administered, the thyroid cells will “suck” up the iodine, because the body has been so depleted.
This diet is for a short time period. The usual time period is around two weeks (14 days) or slightly more. The diet usually begins around two weeks before testing and continues through the testing and treatment period. However, recommendations for the time period can vary, depending partly on the individual patient’s circumstances.
The following is a combination of diet guidelines from several ThyCa medical advisors (who use urine iodine testing to check patients' iodine levels), from researchers' findings presented in medical journals and at ThyCa events, and from input from our 22-member Medical Advisory Council. Your physician may have different guidelines. Please check with your doctor before you start the diet.
General Comments
- Remember: LOW IODINE has NOTHING TO DO WITH SODIUM. The diet is a low-iodine diet, NOT a low-sodium diet. Sodium is in most foods. Table salt is sodium chloride, not sodium.
- Sodium in any form is OK, as long as it is not provided as IODIZED salt. NON-IODIZED salt is OK for the diet, as long as it is not sea salt. As noted below, you should avoid any product or ingredient from the sea. That's because sea-based products are high in iodine.
- Also, this is a "low-iodine" diet, NOT a "no-iodine" diet and NOT an "iodine-free" diet. A low-iodine diet reduces iodine consumptionc(on most diets to below 50 micrograms (mcg) of iodine per day (on some diets to below 80-100 mcg per day). The American Thyroid Association recommends that the low-iodine diet include less than 50 mcg of iodine per day. (The Recommended Daily Allowance of iodine is 150 mcg per day for adults. One teaspoon of iodized salt contains 400 mcg of iodine.)
- During your time on the diet, you may freely eat any foods that are low in iodine (up to 5 mcg per serving). There are lots of foods that you can eat. Pages 10 and 11 have lists. However, avoid foods high in iodine (over 20 mcg per serving). Also, many thyroid cancer specialists' guidelines recommend limiting foods that are moderate in iodine (5 to 20 mcg per serving).
- For recipes and a snack list, use ThyCa’s free Low Iodine Cookbook. You can download it free from our web site and print it out.
- You also can adapt your favorite recipes from your own cookbooks to the low-iodine diet. To do this, eliminate ingredients that are high in iodine, or substitute ingredients from the list of foods and ingredients that are fine on the diet.
- If you follow other dietary guidelines due to allergies, diabetes, other medical conditions, or other reasons, you can adapt your recipes and meal plans. Use the cookbook's lists and tips.
Avoid These Foods and Additives
Avoid the following foods, starting when instructed by your physician before your radioactive iodine test or treatment. Continue as instructed until after your radioactive iodine treatment (often for about 24 hours after). These foods and ingredients are high in iodine (over 20 mcg per serving, according to researchers' presentations at our conferences).
- Iodized salt and sea salt and any foods containing iodized salt or sea salt. Non-iodized salt may be used. For example, Kosher salt is okay unless the label says that it is iodized or sea salt.The reason to avoid sea salt is that all products from the ocean tend to be high in iodine.You can usually find plain, non-iodized salt next to the iodized salt at your grocer. Read the label. (One teaspoon of iodized salt has 400 mcg of iodine.)
- Seafood and sea products (fish, shellfish, seaweed, seaweed tablets, kelp). These are all very high in iodine and should be avoided.
- Foods or products that contain these sea-based additives: carrageenan, agar-agar, algin, alginate, nori (these food additives are seaweed by-products).
- Dairy products (milk, cheese, cream, yogurt, butter, ice cream, powdered dairy creamers, whey, casein, other dairy products). Note: Nondairy creamers often have iodine-containing ingredients, too. A study published in 2004 in the Journal of Clinical Endocrinology and Metabolism reported on tests of 18 brands of milk in the Boston, Massachusetts area. It reported that 250 ml of milk (about 8 ounces, or 1 cup, or 16 Tablespoons) contained from 88 to 168 micrograms of iodine and averaged 115 mcg. It noted that sources of iodine in milk include iodine in cattle feed, the products containing iodine used to clean teats and udders, and a small amount from equipment cleaning products. (Some low-iodine diets allow very small amounts of milk or other dairy, if not listed in the first three ingredients on a label. There is no dairy in any of the recipes in this cookbook.)
- Egg yolks or whole eggs or foods containing whole eggs. Egg whites are acceptable, because they contain little or no iodine. (Some low- iodine diets allow foods with very small amounts of eggs, if not listed in the first three ingredients on a label. The recipes in this cookbook use only egg whites.)
- Commercial bakery products. Avoid bread products that contain iodine/iodate dough conditioners (usually small bakery breads are safe; it’s best to bake it yourself or substitute with Matzos). If you read labels closely, you may also be able to find crackers made only with flour and water. While a few commercial bakery products have tested low in iodine, manufacturing processes can change over time. The study published in the Journal of Clinical Endocrinology and Metabolism in 2004 reported that the iodine content of single slices of 20 different brands of bread ranged from 2.2 mcg to 587 mcg.
- Red Dye #3. However, Red Dye #40 is OK. We suggest that you avoid red, orange, or brown processed food, pills, and capsules. Many red, red-orange, and brown food dyes contain iodine and should be avoided. The problem with food colors is specific to Red Dye FD&C #3 (erythrosine) ONLY. However, the problem is that some food labels do not specify which red dyes are used. Better safe than sorry. For medications, the best source is the Physician’s Desk Reference (PDR), which clearly states the ingredients. For example, Rocaltrol in the 0.5 mcg size is NOT good for the diet because it contains FD&C Red Dye #3. However, Rocaltrol 0.25 mcg does not and is safe for the diet (you can take two of them to get to the 0.5 mcg dose). Please always check with your physician.
- Most Chocolate (for its milk content). Cocoa powder and some dark chocolates are permitted. Check the label for other ingredients not allowed on the low-iodine diet. The ThyCa cookbook has recipes with permitted chocolate.
- Some Molasses. Avoid if sulfured or blackstrap, which is concentrated and has a bitter taste. It's okay to use the milder, fairly sweet unsulfured molasses usually used in cooking and that is the type most often available in grocery stores in the USA. Sulfur is not related to iodine. However, it's a term used on molasses labels. Some diets don't make distinctions between kinds of molasses and say to avoid all molasses.
- Soybeans and most soy products (soy sauce, soy milk, tofu). However, soy oil and soy lecithin are both okay.
- Some beans besides soybeans.The National Institutes of Health diet says to avoid these beans: red kidney beans, lima beans, navy beans, pinto beans, and cowpeas. Other diets do not limit beans.
- Some diets diets say to avoid rhubarb and potato skins. The inside of the potato is fine.
- Iodine-Containing Vitamins, and Food Supplements. Also products containing iodate or iodide. Check the label and ingredients and discontinue completely if iodine is included. Most vitamins with minerals contain iodine.
- If you are taking a Medication that contains iodine, check with your physician.
Limit the Amounts of these Foods
Some diets from thyroid cancer specialists and researchers recommend limiting the daily intake of foods that are moderate in iodine: 5 to 20 mcg per serving.
- Fresh meats. Up to 5 ounces per day of fresh meats such as chicken, beef, pork, lamb, and veal are fine on the low-iodine diet. (Up to 6 ounces, according to one of the researchers, who noted that meat contains 25-130 mcg of iodine per pound.) Whole cuts tend to contain less iodine than do ground meats. Also, check the package label on meats, including whole turkeys, turkey breasts, turkey cutlets, chicken, and all pork products. Many food makers inject broths into turkey or chicken or pork. The label may not indicate whether the broth contains iodized salt. If you are not sure, go to your local butcher for fresh turkey, pork, or chicken.
- Grains, cereals. Up to 4 servings per day of grains, cereals, pasta, and breads without iodine-containing ingredients are fine on this diet. The iodine content depends on the iodine content of the region where the grain was grown. Homemade baked goods and cereals are best on this diet. If you use processed foods, read the labels carefully to avoid iodine-containing ingredients. Also, remember that labels are not always accurate or up to date.
- Rices. Like grains, rices vary in the amount of iodine depending on the region where grown, so rice should be eaten only in limited amounts. Some low-iodine diets recommend avoiding rice. Basmati rice has been mentioned as the best for the diet.
What About Restaurant Foods and Fast Food?
Although restaurants generally use non-iodized salt, it is not possible to know whether a particular restaurant is using iodized salt or sea salt. The manager or serving staff may not know what product is being used, or whether butter or other dairy products are present in foods. The ingredients that chain and fast-food restaurants use may change.
Therefore, we suggest that you avoid restaurant foods other than plain juices or soft drinks, or the inside of a plain baked potato. For most restaurant foods, there is no reasonable way to determine which restaurants use iodized salt. Avoid if in doubt.
What About Manufactured and Processed Foods?
Some published low-iodine diets and researchers' presentations allow salty processed foods and other processed foods. Some of these foods include potato chips and cured and corned foods such as hot dogs, ham, corned beef, sauerkraut, bacon, sausage, and salami.
Currently, manufacturers of processed foods in the USA generally use non-iodized salt. However, food processing techniques can change and labels are not always accurate or up to date.
For that reason, if fresh foods are available, many patients prefer to eat fresh foods during the short period of being on the low- iodine diet. They avoid processed food, because it is not known for sure whether or not iodized salt has been used. For any processed food, it is also important read the label to be sure there is no Red Dye #3.
In the past some patients have contacted manufacturers asking whether or not they used iodized salt in their products or iodine-containing cleansers or sanitizers for their equipment and surfaces involved in food processing. Doing this is NOT recommended for the following reasons:
- Manufacturers cannot guarantee that the ingredients they receive from their suppliers do not contain iodized salt.
- Manufacturers may change procedures and may use iodine-based cleaners or sanitizers on food-processing surfaces, utensils, equipment, and containers used in processing steps.
- Because fewer and fewer manufacturers in the USA have been using iodized salt in their food processing, there seems to be a rise in iodine deficiency. It might become the practice to start using iodized salt again.
Also, some spice blends like chili powder may contain added salt.
Read the ingredient labels on all packaged foods and spices. Some support group participants have compiled lists of brands of processed and packaged foods low in iodine. A list is being reviewed for addition to ThyCa's web site and as an appendix to this cookbook.
Foods That Are Fine to Eat on the Low-Iodine Diet
The low-iodine diet consists mostly of fresh, low-fat, low-calorie foods. Because of this, following this diet greatly reduces the tendency to gain weight while hypothyroid.
The following foods and ingredients are fine to eat. You do not need to limit the quantity, except as noted.
- Fresh fruits and fruit juices, except rhubarb, maraschino cherries (if they contain Red Dye #3), and fruit cocktail with maraschino cherries.
- Vegetables, preferably raw and fresh-cooked or frozen without salt. (But not skins of potatoes, soybeans, and, according to the NIH diet, some other beans like pinto, lima, navy, red kidney, cowpeas).
- Unsalted nuts and unsalted nut butters.
- Grain/cereal products in moderate amounts (see above).
- Fresh chicken, beef, and other meats in moderate amounts (see above).
- Sugar, jelly, honey, maple syrup, and unsulfured molasses.
- Black pepper and fresh or dried herbs.
- All vegetable oils. Salad dressings provided they contain only allowed ingredients.
- Homemade foods (see the free Low-Iodine Cookbook from the ThyCa web site.
- Cola, diet cola, lemonade, sodas (except those with Red Dye #3), non-instant coffee and tea, beer, wine, other alcohol.
Food prepared from fresh meats, fresh poultry, fresh or frozen vegetables, and fresh fruits should be fine for this diet, provided that you do not add any of the iodine-containing ingredients listed above. The cookbook also has a handy snack list.
What if it's not on the "okay" list here?
- There are minor variations in low-iodine diet guidelines provided by different thyroid cancer specialist physicians. These guidelines combine the recommendations of several thyroid cancer specialists whose patients have successfully used their guidelines.
- Some guidelines say just to avoid certain items or certain food categories, and do not give details within categories.
- Other diets list foods and ingredients that are allowed, without limits on quantities consumed.
- Many of our web site visitors and correspondents request details as given here, so that they can plan their menus with their own preferences in mind.
- If your health care professional has recommended that you follow a low-iodine diet, please discuss your diet guidelines with him or her.
A Final Note
The key to coping well with this diet is being prepared ahead of time, especially if you are preparing for RAI by stopping your levothyroxine pills and becoming hypothyroid. Before you start becoming hypothyroid, prepare the basics and freeze. You do not want to be making chicken stock while you are hypothyroid.
Remember also the handy snack list. We suggest that you stock up on snack items from the list for times when you do not feel like cooking.
We encourage you to use our Low-Iodine Cookbook for variety and enjoyment of low-iodine meals and snacks. Thousands of other thyroid cancer survivors have used and enjoyed our recipe collections.
Download the Free ThyCa Low Iodine Cookbook for more information and for recipes.
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AFTER RECEIVING RADIOIACTIVE IODINE
Your Home Stay or Hospital/Home Stay
After receiving RAI for a scan, you will go home immediately. After your RAI treatment dose, you may be sent home immediately, or you may stay in the hospital for one or more days. The size of the treatment dose that involves a hospital stay varies from one jurisdiction to another, and sometimes from one hospital to another in the same jurisdiction. Currently, patients go home immediately after larger doses of RAI than in the past. Your home circumstances, such as whether there is an infant at home, may affect the decision about going home or staying in the hospital for a day or more after your treatment dose.
Below are samples of guidelines from informational materials. Please note that your physician and hospital may have different procedures and guidelines. Discuss your questions and concerns with your doctor.
Information If You Go Home Immediately After Receiving RAI
As your doctor will have explained to you, you will be receiving radioactive iodine as your treatment. Radioactive iodine decreases the function of thyroid cells and inhibits their ability to grow. It is given to you in liquid or pill form and goes directly to the thyroid gland where it is absorbed by the thyroid tissue. Most of the radioactive iodine will be received by your thyroid gland. Any radioactive iodine not collected by the thyroid gland will be eliminated during the first few days through urine, feces, saliva and sweat. The following steps listed below will help assure that the excreted radiation from your body does not contaminate the environment or cause harm to other people.
For information about possible side effects of radioactive iodine, see the information below in the section about the hospital stay.
What do I do at home?
If you go home immediately after a treatment dose, use the following guidelines regarding distance, time, and hygiene.
- Minimize contact (less than 3 feet or 0.6 meter for more than 1 hour each day) with everyone for the first five days, and with small children or pregnant women for eight days.
- Do not sit next to someone in an automobile for more than one hour.
- Sleep in a separate room and use separate bath linen and launder these and underclothing separately for one week.
- Wash your hands with soap and plenty of water every time you use the toilet.
- Rinse the sink and tub thoroughly after using them.
- Use separate eating utensils or disposable eating utensils. Wash eating utensils separately for one week. Do not prepare food for others.
- Flush toilet 2-3 times after use for two weeks after discharge.
- Males should sit when urinating to avoid splashing for one week.
- Discuss with your doctor how long you should wait before starting a pregnancy after your treatment (usually at least two months for males and six months for females).
- If you are breastfeeding, it should be discontinued, but can be resumed for subsequent childbirths.
Information During Your Hospital Stay
As your doctor will have explained to you, you will be receiving radioactive iodine as your treatment. Radioactive iodine decreases the function of thyroid cells and inhibits their ability to grow. It is given to you in liquid or pill form and goes directly to the thyroid gland where it is absorbed by the thyroid tissue. Most of the radioactive iodine will be received by your thyroid gland. Any radioactive iodine not collected by the thyroid gland will be eliminated during the first two days through urine, feces, saliva and sweat. The following steps listed below will help assure that the excreted radiation from your body does not contaminate the environment or cause harm to other people.
How Long Will I Be in Isolation in the Hospital?
After the doctor has given you your treatment you are requested to remain in your room with the door closed until you are released from isolation by the radiation safety officer. This is usually one or more days after you have taken the medication. This can be a great time to get caught up on things such as reading magazines or talking to friends and family on the telephone. Please remember to bring diversional activities with you to the hospital. There is a TV available. You may bring your glasses, but do not bring items such as a laptop computer, which may become contaminated and have to stay in the hospital.
What about Visitors?
It is strongly advised that there be no visitors for the first 24 hours following radiation. We encourage you to use the telephone to communicate with your friends and family. If you receive visitors, a maximum visit of 30 minutes is allowed only. Visitors must wear gloves, protective shoe covers and a gown before entering the room. The amount of space between your visitor and you must be a maximum. This means your visitor must sit at the entrance of the door with you at the other end of the room. At the end of the visit, your visitor must dispose the gloves and shoe covers in the garbage located in the room and place the gown in the hamper. Visitors may not use your washroom or eat or drink any of your food. Pregnant women and children under the age of 18 may not visit during your hospital stay.
How Should I Communicate with my Nurse?
Although your nurse will spend very little time in your room, you can communicate frequently with your nurse by using the telephone and/or the intercom. Your nurse will also check in with you frequently by telephone or intercom to assess how you are doing.
What Should I Wear in the Hospital?
Please wear a hospital gown during your hospital stay and hospital slippers to avoid any contamination of your own clothes by perspiration. Your mattress and pillow will becovered with plastic. Please do not remove these coverings during your hospital stay.
What about Cleaning my Room?
You will be asked to make your own bed, if necessary. Dispose all linen and garbage in plastic bags provided in your room. All cutlery and dishes are to be disposed in a plastic bag also. Rinsing the sink, faucets and tub after use will help keep the radiation contamination to a minimum.
How do I Order my Meals?
You will remain on the low iodine diet. There are no choices. You may order kosher, vegetarian, or diabetic diets.
What about my Medications. Can I still take them?
If you are on medication, please let your doctor know. If your doctor decides that you may continue to take your medication during your hospital stay, please bring enough with you for the duration of your stay. You may store the medication in your room and take when required.
Is there Anything Else I should Know?
Please flush the toilet two or three times after elimination and wash your hands. Remember the urine is one of the key systems that excretes the excess radiation.
"Just for the Men". Please sit to void (pass water) to prevent any splashing contamination of the surrounding area.
Showering two or three times a day and washing your hair will help remove the excreted radiation through perspiration. Extra towels will be provided for you. When getting out of the shower, make sure you have a towel on the floor to step on.
Sucking on sour candies for the first 24-48 hours after radioiodine therapy is recommended by some thyroid cancer specialists to help reduce excessive radiation to your salivary glands. They recommend taking candies every 15 minutes during the day, as well as several times at night.
Further information: A study conducted in Japan and published in early 2005 compared two different timings of starting lemon candy. One group of patients started candy an hour after the radioiodine. The other group waited 24 hours before starting the candy. Both groups were asked to take 1-2 candies every 2-3 hours during the daytime through the 5th day after the radioiodine. The group that waited 24 hours had fewer salivary side effects. The authors concluded that waiting for 24 hours was preferable. However, they also noted that the study had limitations. Among these were that it was not double blinded, was not controlled, and patients in the group waiting 24 hours “tended to be treated more intensively” for salivary side effects. (Nakada, K, et al. Journal of Nuclear Medicine, 46(2): 261-6, 2005).
Several ThyCa medical advisors sent comments about this study. They noted that it is a single study and that it needs verification, because it was “non-controlled and not randomized adequately.” Some recommended conducting a study that is randomized, that includes a no-treatment control group that takes no candy at all, and that measures both acute and chronic symptoms as well as radioiodine uptake and retention in the salivary glands.
The American Thyroid Association’s guidelines published in early 2006 said that “evidence is insufficient to recommend for or against” taking sour candy, or other approaches such as amifostine, drinking a lot of water, or using cholinergic agents.
Radioactive Iodine Treatment - Side Effects
- Sore Throat/Hoarseness: Salivary glands affected by RAI treatment may become swollen. See the section above for more information on this topic.
- Vomiting: Notify the nurse immediately; do not attempt to clean up vomit; please leave clean-up to the radiation safety office/nuclear medicine department.
- Headache: Tylenol plain available for headache
- Constipation/Diarrhea: May be either constipaiion or diarrhea. Must have a bowel movement once a day while in hospital. If no bowel movement then ask the nurse for laxative ordered (should ask for laxative if no bowel movement for that day)
- Fatigue: Resting is good. If necessary, sedation is available at bedtime if there is trouble falling asleep.
Signs to Watch for in Case of Drug Reaction (Allergy)
- Shortness of breath
- Chills/Rigors
- Fever
- Rash/Hives
What about when I go home from the hospital?
- Minimize contact (less than 3 feet or 0.6 meter for more than 1 hour each day) with everyone for the first five days, and with small children or pregnant women for eight days.
- Do not sit next to someone in an automobile for more than one hour.
- Sleep in a separate room and use separate bath linen and launder these and underclothing separately for one week.
- Wash your hands with soap and plenty of water every time you use the toilet.
- Rinse the sink and tub thoroughly after using them.
- Use separate eating utensils or disposable eating utensils. Wash eating utensils separately for one week. Do not prepare food for others.
- Flush toilet 2-3 times after use for two weeks after discharge.
- Males should sit when urinating to avoid splashing for one week.
- Discuss with your doctor how long you should wait before starting a pregnancy after your treatment (usually at least two months for males and six months for females).
- If you are breastfeeding, it should be discontinued, but can be resumed for subsequent childbirths.
ATA Recommendations on Radiation Safety After RAI
Last updated: October 14, 2012