What Is Iodine?
Iodine is a trace element that is found naturally in foods, is added to various foods, and is available in supplement form. It helps make our thyroid hormones thyroxine (T4) and triiodothyronine (T3), which play a role in protein manufacturing, the overall function of our metabolism, and the conversion to usable bodily substances. (3)
Benefits of Iodine
In utero and in infancy, iodine plays an important role in the development of your central nervous and skeletal systems. (2) How much iodine breastfed babies receive depends on how much their moms take in. You can check the amount of iodine in your baby’s formula, if he or she is formula-fed, but rest assured that the U.S. Food and Drug Administration (FDA) requires that infant formulas contain some iodine. (4)
Recommended Intake of Iodine
Iodine deficiency is most catastrophic to the developing brain. Therefore, requirements in pregnancy and lactation are much higher. (2) The Recommended Dietary Allowances (RDAs) for iodine are: (2)
Birth to 6 months: 110 micrograms (mcg)7 to 12 months: 130 mcg1 to 3 years: 90 mcg4 to 8 years: 90 mcg9 to 13 years: 120 mcg14 to 18 years: 150 mcg19 years and older: 150 mcgPregnancy: 220 mcgLactation: 290 mcg
(*Adequate intake) RDAs are set to show the amount required to meet the needs of 97 to 98 percent of healthy people. When there’s not strong enough evidence to show what the RDA is for a certain nutrient, adequate intake (AI) is offered instead as an estimate for what amount of the nutrient, mineral, or element is enough. (5)
You develop a goiter. Your thyroid is the butterfly-shaped gland at the base of your neck. With iodine deficiency, the thyroid can become enlarged, which is called a goiter. This can make it difficult to swallow and breathe.Thyroid function is slow. This is called hypothyroidism. In the United States, there are far more common causes of an underactive thyroid than iodine deficiency, including problems with the pituitary gland and autoimmune disease. (7) Hypothyroidism can make you feel cold, slow down cognitive function, and cause a low mood.You’re having pregnancy complications. Because iodine is so critical in fetal development, severe deficiency may lead to miscarriage, stillbirth, preterm delivery, and birth defects.
In the United States, iodine deficiency has historically been low. But certain groups may be at a higher risk. (1)
Pregnant and Nursing Women
Pregnant and nursing mothers have higher iodine needs because of the role of iodine in a developing fetus, brain development, and growth of the baby. Pregnant women should get at least 220 mcg per day. Nursing women need 290 mcg. (2)
People on Strict Diets
You might try a fad diet to lose weight, but sometimes these eating approaches can pose unintended consequences. Whether you are eliminating a few foods or food groups for the goal of better health, to control a food allergy, or to manage a medical condition, diets with broad-stroke food group eliminations require a closer look. As mentioned earlier, foods abundant in iodine are dairy, grains, seafood, and iodized salt. A small study looking at iodine levels in people following vegetarian diets concluded that these groups may be more at risk for deficiency. (8) A 2017 study found that following a Paleo diet may also increase the odds of falling short of the nutrient. (9)
Patients With Hypertension
If you have high blood pressure (hypertension) or heart disease, your doctor may have advised you to reduce your salt intake. Because of that, you may worry that eating less salt will put you at risk for deficiency. Here’s what you should know: If you are already iodine deficient and eat a low-sodium diet, your iodine levels will likely get worse. (10) But if you start out with sufficient levels, lowering your salt intake is safe and will not likely lead to deficiency. If you have hypertension and are worried about dietary changes, talk to your doctor.
Using ‘Fancy’ Salts
Also important to note: Not all salt, including pink Himalayan salt, is iodized. Be sure to work with a registered dietitian to make sure you’re getting enough of the element in your diet if you think you may be at risk of a deficiency. (11)
Individuals With Other Nutrient Deficiencies
Other nutrient deficiencies uncommon in the United States, such as iron, selenium, vitamin A, and possibly zinc, may impact iodine nutrition and thyroid function, though more studies are needed. (12) In the United States, older Americans may fall below the recommended intake for zinc. (13) Vitamin A deficiency is rare among all age groups, but some people who have fat malabsorption are at risk, including those with cystic fibrosis. (14) Selenium deficiency is also rare in the United States, but people undergoing kidney dialysis or those living with HIV are at higher risk. (15) On the other hand, iron deficiency is relatively more common in the United States. It’s higher in pregnant women and those with blood loss. Vegetarians, infants, and children are also at a greater risk of iron deficiency. (16) There may be a cumulative effect on deficiency risk when you are in one or more high-risk categories.
Those at Risk Who Eat Foods High in Goitrogens
Goitrogens are substances in some foods that block iodine’s ability to get to the thyroid. Goitrogenic foods may not cause an actual iodine deficiency if you’re getting enough iodine in your diet. But if your iodine intake is already low, the goitrogens may have a compounding effect. Foods high in goitrogens include: (2)
SoyCabbageBroccoliCauliflowerBrussels sprouts
Just know that you need to limit these foods only if you’re actively or borderline deficient in iodine. But if your doctor suspects that you have iodine deficiency, the condition can be diagnosed on an individual basis with blood tests that measure thyroid hormones. (17)
Prognosis of Iodine Deficiency
Eating foods or taking supplements as recommended by your doctor will help bring the iodine levels up in your body. You may also have to be treated if iodine deficiency leads to health problems. For instance, if you have a goiter (an enlarged thyroid) that’s caused by a lack of iodine in your diet (there are other reasons for a goiter), then using iodized salt or eating seafood twice a week is one lifestyle remedy that can give you the amount your body needs. (18)
If You Don’t Have Signs of Iodine Deficiency, Do You Need a Supplement?
Most people in the United States do not need to take an iodine supplement, but if you fall in one or more of the high-risk categories, this might be something to consider. Keep in mind that the tolerable upper limit set by the National Institutes of Health is 1,100 mcg for adults. (2) Ask your doctor or registered dietitian nutritionist (RDN) before starting any supplementation, as there may be some interactions with over-the-counter and prescription medications you may be taking. That said, topical and oral supplementation of iodine has shown some effectiveness for:
Venus leg ulcers (topical) (20)Iodine deficiency and insufficiency (2)Hypothyroidism (only if iodine deficient; too much iodine can also cause hypothyroidism) (2)Fibrocystic breast disease (2)Reduction in infection risk with catheters and surgery incisions (topical) (21)
Most supplements come in the form of potassium iodide (Pima) and sodium iodide, but there are other options available, including kelp (a type of seaweed). Most multivitamins contain iodine (be sure to check the label). Many supplements on the market have iodine amounts well above the tolerable upper limit of 1,100 mcg per day, so be careful going above this amount without consulting your doctor or pharmacist first. (2) Oddly enough, getting too much iodine may have the same effects as not getting enough — for example, both effects may lead to goiter, elevated thyroid-stimulating hormone (TSH), and hypothyroidism. Therefore, do not treat your symptoms on your own. Get a proper diagnosis first, and then work with your doctor to stabilize your iodine levels. (6) You and your doctor will likely discuss the following:
Your Health Work with your doctor to determine if you fall into one or more of the high-risk categories for iodine deficiency. If so, you may need to supplement your diet.The Reasoning What do you need to take iodine for?The Type Which form of iodine is best for your needs?The Amount How much iodine do you need? (See below for upper limits.)
The National Institutes of Health has set upper limits for iodine. By age group, they are as follows: (2) Birth to 12 months Not established Children 1 to 3 years 200 mcg Children 4 to 8 years 300 mcg Children 9 to 13 years 600 mcg Teens 14 to 18 years 900 mcg Adults 19 years and older 1,100 mcg Before supplementing your diet with iodine, consider what other medication you’re taking. The supplement may make your medication less effective and potentially cause harmful interactions. (2)
Taking a potassium iodine supplement at the same time as blood pressure medication from the ACE inhibitor class may raise your potassium to an unsafe level. Examples of ACE inhibitors include lisinopril (Zestril) and benazepril (Lotensin).Anti-thyroid medication, such as methimazole (Tapazole) and propylthiouracil (PTU) may have a compounding effect by producing too little thyroid hormone.When taken with iodine, potassium-sparing diuretics can cause potassium levels in your blood to soar too high. (2) High potassium can cause potentially harmful heart rhythm changes. (22)
It’s always a good idea to tell your doctor and your pharmacist what supplements you’re taking. They can review any possible interactions with your current medication list and reconcile any issues for your safety. The following are some foods that are high in iodine: (2)
Seaweed, whole or sheet (1 g): 16 to 2,984 mcg (between 11 and 1,989 percent DV, depending on the water source)Baked cod (3 ounces [oz]): 99 mcg (66 percent DV)Low-fat, plain yogurt (1 cup): 75 mcg (50 percent DV)Medium white potato with skin: 60 mcg (40 percent DV)Reduced-fat milk (1 cup): 56 mcg (37 percent DV)Fish sticks (3 oz): 54 mcg (36 percent DV)Enriched white bread (2 slices): 45 mcg (30 percent DV)Shrimp (3 oz): 35 mcg (23 percent DV)Chocolate ice cream (½ cup): 30 mcg (20 percent DV)Iodized salt (¼ teaspoon): 71 mcg (47 percent DV)
Prevention of Iodine Deficiency
While iodine deficiency is not common in Western countries, you can prevent it by eating a varied diet, including good food sources of iodine, like seafood and yogurt. (2) Cooking with iodized salt is one of the main ways to maintain sufficient levels, but this doesn’t mean you should add salt to your food in order to reach your iodine quota. If you’re in an at-risk group, such as if you are pregnant or want to become pregnant, take a multivitamin or prenatal supplement that contains iodine. Other people who are concerned with the amount of iodine in their diet or have thyroid disease (caused by an iodine deficiency) should talk to their doctor about if a supplement is needed.
Hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid)Development of a goiter (enlarged thyroid gland)Pregnancy complications and fetal abnormalities
Enlarged Thyroid Gland (Goiter) Symptoms of a goiter include swelling of the neck where the thyroid is located, trouble swallowing or breathing, and choking (especially while lying down). (6) If you suspect a goiter, contact your doctor and request a physical assessment. If iodine deficiency is suspected, you can ask your doctor to run a 24-hour urine iodine test for a proper diagnosis. (26) Hypothyroidism Symptoms of hypothyroidism include unexpected weight gain, fatigue, feeling cold, dry skin, and even depression. (7) If you think you may have hypothyroidism, consider getting your thyroid-stimulating hormone (TSH) levels checked. Pregnancy-Related Problems Iodine deficiency in pregnancy can result in miscarriages, stillbirth, early deliveries, and, in cases of extreme deficiency, congenital defects in babies. Check your prenatal vitamins, as not all of them have supplemental iodine. Only 60 percent of prenatals in the United States contain iodine. Be sure yours has 150 mcg of iodine. (6) This nonprofit is focused on global, universal salt iodization to prevent iodine deficiency. Check out their public message board and forum for common questions — and to post your own. American Thyroid Association NIH Office of Dietary Supplements Their consumer page presents an easy-to-read format detailing the role of iodine for health, how much you need, and an overview of what science says about the mineral’s connection to a variety of diseases and conditions.
