Iodine deficiency is one of the leading causes of hypothyroidism. It's important to add iodine into your diet.

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Iodine is an essential nutrient. That means your body needs it, but it can’t make it. If you don’t get enough iodine in your diet, you could become iodine deficient which will affect important functions, such as keeping your thyroid healthy. Your body needs iodine to make thyroid hormones. All the symptoms of iodine deficiency are due to low levels of thyroid hormone, called hypothyroidism. In fact, iodine deficiency is the most common cause of hypothyroidism worldwide.

Risk Factors | Symptoms | Prevention

Iodine deficiency can be dangerous for anyone because your thyroid makes hormones – chemical messengers – that travel to every part of your body. Without enough thyroid hormones, your body can’t use energy. Everything slows down. Iodine deficiency is especially dangerous for pregnant women and breastfeeding women, not really for the women, but for their babies. Babies in the womb and at the breast can have major brain development problems without enough thyroid hormones.

When you take in iodine through your diet, your thyroid gland pulls out enough iodine to make thyroid hormones. The rest of the iodine goes out in your urine. Measuring iodine in a urine sample is a simple way to find out if a person is iodine deficient.

According to the World Health Organization, an adequate level of iodine in urine is over 100 micrograms per liter (mcg/L). For pregnant and breastfeeding women an adequate level is over 150 mcg/L. Studies show that many pregnant women are not meeting this requirement. The National Health and Nutrition Examination Survey found that urinary iodine levels for all Americans dropped by half between the 1970s and the 1990s.

* Adequate Intake (AI)
Information from National Institutes of Health. 

Are You at Risk for Iodine Deficiency?

Back in the 1920s, before iodine was added to salt, iodine deficiency was common. Thyroid glands of people who were iodine deficient worked hard to get as much iodine as they could, causing enlarged thyroids, called goiters. If you have an adequate diet, your risk for iodine deficiency is very low. Iodine is added to salt, some bread, and it occurs naturally in seafood, dairy products, eggs, and beef. Iodine levels low enough to cause hypothyroidism are less than 20 mcg/L.

Iodine deficiency may be increasing because more people are avoiding salt or using natural salts, like Kosher or pink salt without iodine. More people have also become strict vegetarians, eliminating many sources of natural iodine. Fruits and vegetables have very little iodine. Cow’s milk is a good source of iodine, but many people have now switched to milk substitutes, like almond milk. You could be at risk for iodine deficiency if you are pregnant or breastfeeding, you are a strict vegetarian, or you do not use iodized salt.

A recent study in the International Journal of Environmental Research and Public Health found that women of child-bearing age in Australia who were vegans had average urine iodine of 44 mcg/L, not enough to cause hypothyroidism, but dangerous for a baby developing in the womb. When they tested women who had switched from iodized salt to pink Himalayan salt, the average iodine levels were only 23 mcg/L, which is dangerously close to the hypothyroid level.

Iodine Deficiency Symptoms

The first warning of iodine deficiency is usually an enlarged thyroid gland. Other iodine deficiency symptoms include:

Symptoms of iodine deficiency are the same as those of hypothyroidism. The biggest indicator of iodine deficiency is an enlarged thyroid gland.

• Fatigue or weakness
• Weight gain
• Sensitivity to cold
• Dry skin and dry hair
• Constipation
• Hoarseness
• Joint pains or stiffness
• Irregular menstrual periods

How to Prevent Iodine Deficiency with Iodine Rich Foods

Although iodine is included in many supplements, the most reliable way to get enough iodine is by using iodized salt. One teaspoon of iodized salt has all the iodine you need for one day, even if you are pregnant or breastfeeding. Surprisingly, only about 60 percent of prenatal vitamins contain iodine. Seaweed is an excellent source of iodine, but if you are not a fan of seaweed, you can get enough iodine by including these iodine-rich foods in your diet:

Iodine-rich foods include fish, yogurt, chicken, and eggs. Eating these foods can prevent iodine deficiency and hypothyroidism.

• Iodized bread
• Fish
• Shellfish
• Yogurt
• Cow’s milk
• Eggs
• Cheese
• Beef
• Chicken
• Soy

Iodine deficiency is a major problem worldwide and a growing problem for women who are pregnant or breastfeeding. Severe iodine deficiency (hypothyroidism) in mothers can put a child at risk for intellectual disability. In fact, iodine deficiency in pregnancy is the most common cause of preventable intellectual disability in children.

If you have any symptoms of iodine deficiency, or you do not have any natural sources of iodine in your diet, ask your health care provider if you should have a urine iodine test. This is especially important if you a pregnant or planning to become pregnant.