What Is Iodine?
Iodine is an important mineral found in nature, especially in oceans. Your body needs iodine to function properly. But it can't make it on its own. Instead, you need to get enough iodine through the foods you eat.
A wide variety of foods such as fish, seaweed, and dairy products, all contain iodine. You can also get it in the form of iodized salt, which is table salt with a tiny amount of iodine added to it. In the U.S., iodized salt has been for sale in stores since the early 1900s. At that time, many people in parts of the U.S. weren't getting enough iodine in their diets. That's no longer an issue, largely because of the widespread use of iodized salt.
So what does iodine do that's so important? It's key for thyroid health.
What Does Iodine Do?
Your thyroid is a butterfly-shaped gland in the front of your neck. It relies on iodine to make the thyroid hormone that's key for metabolism, your body's process for turning the food you eat into energy.
Thyroid hormone consists of two separate hormones:
- Thyroxine (T4)
- Triiodothyronine (T3)
T4 doesn't directly affect your cells. Your body makes it and turns it into T3, which then affects body functions such as:
- Weight loss or gain
- Heart rate
- Body temperature
- Digestion
- Muscle control
- Skin health
- Bone health
Not getting enough iodine can lead to hypothyroidism, meaning that your thyroid isn’t working as well as it should. That can cause symptoms such as fatigue, joint pain, and fertility issues (trouble getting pregnant). Iodine is also crucial for babies and young children because it helps their brains and bones develop properly.
Many people get all the iodine they need from food. But in some cases, your doctor may want you to take a supplement to help ensure you're getting enough of this important mineral.
Iodine Supplements
In the U.S., it's rare to need more iodine than you get in food. But If you have concerns that your levels are low, speak with your doctor. They can test your levels and figure out if you need a supplement.
Most iodine supplements can be bought over the counter, sometimes in the form of kelp supplements. You may also see a form of iodine in different types of multivitamins and prenatal vitamins.
Your doctor could also prescribe a stronger version, such as potassium iodide or sodium iodide.
Benefits of Iodine
Iodine’s most important role is to ensure proper thyroid function. It helps regulate T3 and T4.
Other health benefits of iodine include:
Proper development during pregnancy
When you're pregnant, you need more iodine than usual in your diet. Iodine is key to making sure your baby's brain develops like it should. Research shows that babies whose mothers didn't get enough iodine during pregnancy are more likely to have intellectual delays and lower IQs than children born to mothers who get enough iodine.
Healthy birth
Getting enough iodine during pregnancy can help your baby be born at a healthy birth weight. Low levels of thyroid hormone have been linked to an increased risk of miscarriage, as well as premature birth (your baby being born before the 37th week of pregnancy).
Improved brain health in children
The brain-developing benefits of iodine for babies extend into early childhood as well. Not getting enough iodine is the most common cause of brain damage in young kids. It can affect how they think and how well they're able to learn gross motor skills such as standing, walking, and bending over.
If you're nursing your child, you'll also have higher iodine needs than usual. That's because you're passing this mineral onto your baby through your breast milk.
Lowered risk of goiter
A goiter is an enlarged thyroid gland, and it often happens as a result of hypothyroidism (underactive thyroid). The most common cause is a lack of iodine in your diet. Getting enough iodine can help prevent this gland in your neck from swelling.
May treat fibrocystic breast disease
Fibrocystic breast change isn't a type of cancer. It's a condition that causes painful lumps in your breasts. It typically occurs when you're regularly having periods, but it could also affect you after menopause (when you no longer have periods). Some research signals that iodine may help reduce the pain and other symptoms of fibrocystic breast disease, but more research is needed to confirm this.
May help prevent some types of cancer
For instance, some research shows that you're more likely to have stomach cancer when you don't get enough iodine from your diet. But more research needs to be done to understand the role this mineral plays.
May help treat thyroid cancer
Radioactive iodine can be used to help treat people with thyroid cancer. Because your thyroid absorbs nearly all of the iodine you take in, radioactive iodine is able to destroy cancer cells in your thyroid that weren't removed by surgery. It may also help improve your outlook if you have a type of thyroid cancer that's spread to other parts of your body.
May help treat breast cancer
Some early research shows that certain iodine supplements could be a helpful tool in breast cancer treatment. A very small study found that when they were taken before surgery and chemotherapy, patients had better results and fewer side effects. But a lot more research needs to be done. And it's important to note that there is no evidence that iodine supplements alone can treat cancer.
Iodine benefits skin
Some wound cleaners and surgical hand soaps contain povidone-iodine, which is good at killing bacteria on your skin and helps prevent infections. You might have used an iodine antiseptic before and never realized it. Some brand names include Betadine, First Aid, and Povidex.
Side Effects of Iodine
Getting enough iodine is key for your thyroid to function well. But getting too much can lead to health issues as well, such as:
Iodine toxicity
Getting too much iodine can lead to iodine toxicity, also called iodine poisoning. Symptoms vary depending on how much you take. You could have a metal-like taste in your mouth and an upset stomach. Or you could throw up, have diarrhea, run a fever, and have a weak pulse. In severe cases, too much iodine can put you into a coma, meaning that you aren't conscious and can't respond to others.
Excess amounts of iodine can also lead to an overactive thyroid, a condition that's also called iodine-induced hyperthyroidism (IHH). It causes your body to turn the calories you eat from food into fuel way too quickly. As a result, you could have symptoms such as a racing heart, irregular heartbeat, weight loss without trying, and frequent bowel movements (poop.) When you have hyperthyroidism, it's common to also feel anxious and easily irritated.
Goiter
While making sure you get enough iodine from your diet can help prevent a goiter from forming, the opposite is also true. Too much iodine in your body can also cause the thyroid gland in your neck to become enlarged. Some people get what's called an obstructive goiter. Your thyroid gland can grow so large that it's hard for you to swallow or breathe easily during exercise. It can also cause a hoarse voice, coughing, and snoring.
Thyroid cancer
Very high amounts of iodine in your diet may actually increase your risk of thyroid inflammation and thyroid cancer.
Medication interactions
Iodine supplements may interact with many different types of medications. For instance, taking an iodine supplement while also taking antithyroid medications, such as methimazole, may cause your body to produce too little thyroid hormone. Potassium iodide supplements, used along with ACE inhibitors, may cause potassium to build up in your blood. If it reaches unsafe levels, you have a condition called hyperkalemia. It can lead to serious heart-related issues and can even be life-threatening.
Iodine Deficiency
Ocean water contains a large amount of iodine. It naturally evaporates into the air, then returns to the earth in rain. That's why small amounts of iodine can be found in drinking water, soil, and food crops all over the world. But you won't find the same amount everywhere.
You're at higher risk of iodine deficiency if you live at a high altitude, in a place that easily floods, or in an inland region, far away from a coast.
The symptoms of iodine deficiency include:
- Puffy skin
- Very dry or scaly skin
- Very dry or thinning hair
- Fatigue (feeling tired even after resting)
- Weight gain
- Often feeling cold
- Weakness/low energy
- Feeling easily confused
- Constipation (trouble going poop)
- Fertility issues
- Goiter
- Hoarse voice
- Finding it hard to swallow or breathe easily
You don't have to have all of these symptoms to have an iodine deficiency. Many people don't.
If you have a goiter, your doctor may be able to confirm that you have a thyroid deficiency during a physical exam. They can also make the diagnosis through the results of a blood test which measures your levels of thyroid hormone, or an imaging test, like a thyroid ultrasound, which provides a detailed look at this gland.
How Much Iodine You Should Consume per Day
The daily amount of iodine you need from food, drinks, and supplements depends on your age:
- Birth to 6 months: 110 micrograms
- 7 months to 1 year: 130 micrograms
- Children aged up to 8 years: 90 micrograms
- Children aged 9 to 13: 120 micrograms
- Teens and adults: 150 micrograms
- Women who are pregnant: 220 micrograms
- Women who are breastfeeding: 290 micrograms
It's important not to exceed these limits without first talking to your doctor.
Natural Sources of Iodine
In general, most people get all the iodine they need at meals. Some iodine-rich foods include:
- Seaweed
- Some types of fish (such as cod and tuna)
- Shellfish (such as shrimp and oysters)
- Dairy products
- Eggs
- Chicken
- Beef liver
- Iodized salt
- Some infant formula (look for "fortified" on the label)
You may be at higher risk of an iodine deficiency if you follow a vegan diet or don't eat any items on this list.
Iodine and Shellfish Allergy
In the 1970s, some experts started to believe that an allergy to shellfish like crab, lobster and clams was really an allergy to iodine, since shellfish contains high amounts of it. Many people started to believe this, even though the testing that was done to check this claim was faulty.
It's now widely understood by medical experts that a shellfish allergy isn't because of iodine. It's due to a protein found in shellfish called tropomyosin.
We now know that iodine isn't an allergen. It doesn't trigger a reaction from your immune system.
Iodine and Baby Oil
Some people say that mixing baby oil and iodine will help you get a tan or remove excess body hair. These are both myths. There isn't any proof that these homemade mixtures work.
Although it's not common, iodine can irritate your skin. After coming into contact with it, you might notice itching, redness, crusting, or blisters. If so, call your doctor for advice.
Takeaways
Iodine is a mineral that your body needs to make thyroid hormone. You likely get enough iodine from foods such as fish, eggs, and dairy products, as well as from iodized salt. Check with your doctor before starting an iodine supplement since excess iodine can cause health issues.
