Iodine defined: Why you need the nutrient and why iodine deficiency can be harmful
EVERYDAY HEALTH
Angela Lemond, RDN
When the average American hears the word iodine, they often think of salt. And thats no surprise, considering more than 90 percent of U.S. households use iodized salt to help boost the flavor of their food. Indeed, most food manufacturers have been participating in the voluntary program of adding iodine to table salt since the 1920s, to help correct iodine deficiencies.
Here, take a deep dive into what the element is, why you need it, and what can happen if you dont get enough.
What is iodine exactly and where is it found?
Iodine is a trace element thats found in food, added to various foods, or is available in supplement form. It makes up 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.
Why you need iodine and what it does for your health
In utero and in infancy, iodine plays an important role in the development of your central nervous and skeletal systems. How much iodine breast-fed babies receive depends on how much their moms take in. You can check the amount of iodine in your babys formula if he or she is formula-fed, but rest assured that most commercially available formulas in the United States contain enough of the element.
How much iodine do you need? The age-based recommendations
Iodine deficiency is most catastrophic to the developing brain. Therefore, requirements in pregnancy and lactation are much higher.
The Recommended Dietary Allowances (RDAs) for iodine are:
Birth to 6 months: 110 micrograms (mcg)
7 to 12 months: 130mcg
1 to 3 years: 90mcg
4 to 8 years: 90mcg
9 to 13 years: 120mcg
14 to 18 years: 150mcg
19 years and older: 150mcg
Pregnancy: 220mcg
Lactation: 290mcg
Adequate intake (AI)
RDAs are set to show the amount required to meet the needs of 97 to 98 percent of healthy people.
When theres not strong enough evidence to show what the RDA is for a certain nutrient, AI is offered instead as an estimate for what amount of the nutrient, mineral, or element is enough.
What are the best food sources of iodine?
Iodine content in food varies by soil content, fertilizers, and irrigation. Seafood is higher in iodine due to the content of ocean waters and can vary by area. Processed foods are higher due to additives in processing.
The daily value (DV) for iodine is 150 mcg for people ages 4 and older. Any foods providing 20 percent or more of iodine are considered good sources of the element.
Following are some foods that are high in iodine:
Seaweed, whole or sheet (1 g): 16 to 2984mcg (between 11 and 1,989 percent DV, depending on the water source)
Baked cod (3 oz): 99mcg (66 percent DV)
Low-fat, plain yogurt (1 cup): 75mcg (50 percent DV)
Iodized salt ( teaspoon): 71mcg (47 percent DV)
Medium white potato with skin: 60mcg (40 percent DV)
Reduced-fat milk (1 cup): 56mcg (37 percent DV)
Fish sticks (3 oz): 54mcg (36 percent DV)
Enriched white bread (2 slices): 45mcg (30 percent DV)
Shrimp (3 oz): 35mcg (23 percent DV)
Chocolate ice cream ( cup): 30mcg (20 percent DV)
Iodine deficiency: Health risks, whos at risk, and symptoms of deficiency
Iodine deficiency can cause hypothyroidism, but iodine excess can cause it as well.
Pregnant and nursing women
Pregnant and nursing mothers have higher iodine needs due to the function of iodine on a developing fetus, brain development, and growth of the baby. Pregnant women should get at least 220 mcg per day.
You might try a fad diet to lose weight, but sometimes these eating approaches can pose unintended consequences. Whether you are eliminating a food 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. People following dairy-free, vegan, clean, or paleo diets may be at a higher risk of iodine deficiency. Although the typical American diet is plentiful in salt, you may unintentionally develop a deficiency if you dramatically reduce your salt intake for health reasons like high blood pressure (hypertension) or heart disease.
Also important to note is not all salt, including pink Himalayan salt, is iodized. Be sure to work with a registered dietitian to make sure youre getting enough of the element in your diet if you think you may be at risk of a deficiency, according to an article published in the American Journal of Hypertension.
Individuals with other nutrient deficiencies
Other nutrient deficiencies, such as iron, selenium, vitamin A, and possibly even zinc, may impact iodine nutrition and thyroid function, according to a paper published in the journal Best Practice Research Clinical Endocrinology Metabolism.
In the United States, older Americans may fall below the recommended intake for zinc, according to research published in The Journal of Nutrition. Vitamin A deficiency is rare among all age groups, but some people who have fat malabsorption are at risk, including those with cystic fibrosis. Selenium deficiency is also rare in the United States, but people undergoing kidney dialysis or those living with HIV are at higher risk.
On the other hand, iron deficiency is relatively more common in the United States. Its higher in pregnant women and those with blood loss. Vegetarians, infants, and children are also at a greater risk of iron deficiency.
There may be a cumulative effect on deficiency risk when you are in one or more high-risk categories.
Goitrogens are substances in some foods that block iodines ability to get to the thyroid. Goitrogenic foods may not cause an actual iodine deficiency if youre 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:
Soy
Cabbage
Broccoli
Cauliflower
Brussels sprouts
Just know that you only need to limit these foods if youre actively or borderline deficient in iodine
.
What are the signs and symptoms of iodine deficiency?
Its important to recognize iodine deficiency signs so you can get prompt treatment. Below are some of the most common ones.
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). 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.
Hypothyroidism Symptoms of hypothyroidism include gaining weight unexpectedly, experiencing fatigue, feeling cold, having dry skin, and even suffering from depression. 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 vitamin, as not all of them have supplemental iodine. Be sure yours has at least 220 mcg of iodine.
Iodine supplementation: Tips for upping your intake with capsules
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 set at 1,100 mcg for adults. Anything over 500 mcg will likely have an undesirable effect on thyroid hormones.
Ask your doctor or registered dietitian-nutritionist (RDN) before starting any supplementation, as there may be some interactions with your current over-the-counter and prescription medication. With that said, topical and oral supplementation of iodine shows some effectiveness for:
Leg and foot ulcers
Iodine deficiency and insufficiency
Hypothyroidism (only if iodine deficient; too much iodine can also cause hypothyroidism)
Fibrocystic breast disease
Hormone-related breast pain
Anti-inflammatory effects for mouth sores, pink eye, and gum infections (topical)
Reduction in infection risk with catheters and surgery incisions (topical)
Most supplements come in the form of potassium iodide and sodium iodide, but there are also vegan supplements coming from kelp (a type of seaweed). Most multivitamins contain iodine. 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.
More on nutritious foods
Interestingly 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.
You and your doctor will likely discuss the following:
Your Health Work with your doctor to determine whether you fall into one or more of the high-risk categories for iodine deficiency. If so, you may need to supplement your diet with more than only iodine.
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:
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
Common medication interactions with iodine to be aware of
Before supplementing your diet with iodine, consider what other medication youre taking. The supplement may make your medication ineffective and potentially cause harmful interactions:
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 Lotensin (benazepril).
Anti-thyroid medication, such as Tapazole (methimazole) and propylthiouracil (PTU) may have a compounding effect by producing too little thyroid hormone.
Any other medication that has potassium that is taken with potassium iodide could cause blood levels of potassium to go too high. High potassium can cause potentially harmful heart rhythm changes.
Its always a good idea to tell your doctor and your pharmacist what supplements youre taking. They can review any possible interactions with your current medication list and reconcile any issues for your safety.
Answers to frequently asked questions about iodine and iodine deficiency
Do you really need iodine for health?
Yes. Iodine is an essential mineral required for basic metabolic health, and is even more important in fetuses, infants, and children for cognitive development and growth. Iodine cannot be formed in the body; we must take it in.
Is it safe to put iodine on your skin?
For most people, topical iodine is safe. For some, though, it may cause skin rash, so be careful and test a very small area first to make sure you do not have a negative reaction. Keep in mind that topical iodine is absorbed into the system, so stay within recommended amounts.
What foods contain iodine naturally?
Foods that contain iodine include iodized salt, dairy (through sanitation practices), seafood, and grains.
What are the symptoms of iodine deficiency?
Symptoms of iodine deficiency vary. They could range from fatigue, depression, weight gain, and constipation (hypothyroid), to manifestations of a goiter, such as enlarged thyroid, and trouble breathing and swallowing, especially when lying down.
