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Iodine Intake and the Risk of Hypothyroidism: What You Need to Know

Learn the effects of iodine deficiency and how you can support your thyroid health. 
Iodine Intake and the Risk of Hypothyroidism: What You Need to Know

Mary Shomon

Patient Advocate

Written by
Medically Reviewed by:
, last updated: 
November 19, 2021
Medically Reviewed by:
Last updated:
November 19, 2021

In this article

If you’re hypothyroid, you already know that iodine is a crucial nutrient. You also know that as the nutritional building block for thyroid hormone production, you can’t afford to be deficient in iodine. Like most Americans, you probably think you are getting sufficient amounts of iodine, but is that true? Let’s look at the increasing rate of iodine deficiency in the U.S. and what you can do about it.

Introduction

Iodine, an element, is found in soil that was at some point covered by seawater, crops grown in that soil, and in seawater itself. The primary sources of iodine are foods naturally rich in iodine or fortified with iodine.

Iodine is the primary ingredient in the production of thyroxine (T4) and triiodothyronine (T3), the two primary thyroid hormones produced by the thyroid gland.

A deficiency of iodine is a proven cause of thyroid dysfunction. Without enough iodine, it’s difficult for your thyroid gland -- and thyroid hormones -- to work effectively. Iodine deficiency can lead to hypothyroidism – an underactive thyroid. It can also cause an enlarged thyroid gland, called goiter, and various pregnancy-related problems. Thyroid hormone is necessary for fetal brain development. Children born to mothers with a severe iodine deficiency face the possibility of serious cognitive and physical disabilities and an increased risk of a condition known as cretinism. Iodine deficiency is, in fact, the leading preventable cause of intellectual disability in the world.

How much iodine do you need?

According to the American Thyroid Association and the Institute of Medicine, the following are the Recommended Dietary Allowance (RDA) intake levels for iodine:

  • Birth to 6 months: 110 mcg
  • 7–12 months: 130 mcg
  • Ages 1-13: 120 μg per day
  • Ages 14+, including adult men and women: 150 μg per day
  • Women who are planning to conceive or who are pregnant: 220 μg per day
  • Women who are breast feeding: 290 μg per day

The rise in iodine deficiency

Iodized salt was introduced in the United States in 1924 to help prevent iodine deficiency and its resulting health problems. By the 1940s, iodine deficiency was no longer a problem in the U.S., thanks to iodization programs.

However, iodine deficiency started to reemerge in the 1970s and continues to increase. Several factors appear to be associated with the increased risk of iodine deficiency:

  • Dietary iodine intakes have decreased by 50% since the 1970s.
  • Intake of dairy products – the primary source of dietary iodine in the U.S. – has declined due to veganism and lactose intolerance.
  • Processed food consumption is on the rise, but most of these processed foods use non-iodized salt.
  • Americans increasingly prefer to salt foods with non-iodized specialty salts, like kosher salt, Himalayan pink salt, and sea salt.

A study in the journal Thyroid in August of 2022 did a deep dive into trends in iodine status in children and adults in the U.S. between 2001 and 2020. They used the renowned National Health and Nutrition Examination Survey (NHANES). Based on their assessment of the Institute of Medicine’s guidelines for the estimated average requirement (EAR) of iodine, the researchers had several relevant conclusions.

  • Between 2001 and 2020, among children, the prevalence of iodine intake below the EAR rose from 15.4% to 27.6%. This increase in the degree of iodine deficiency in children is significant.
  • In adults, the prevalence of iodine intake below the EAR rose from 15.0% to 17.9%. Low iodine intake was more prevalent in women compared to men.
  • Children and adults who “never or rarely” consumed milk products were more likely to have inadequate iodine intake compared to those who “sometimes” and “often” consumed milk products.

Reversing iodine deficiency

Testing can help you determine if you’re iodine deficient. The Paloma blog has a helpful article covering blood tests for iodine, and the gold standard, the urinary iodine concentrations test,

If you are deficient in iodine, the next step is to increase your iodine intake. There are three key ways to accomplish this.

1. Increase your use of iodized salt. (Again, remember that kosher salt, Himalayan pink salt, and sea salt are not iodized.)

2. Add more iodine-rich foods to your diet. Good sources of iodine include:

o   Iodine-fortified bread and cereals

o   Dairy products, especially milk, cheese, and yogurt

o   Eggs

o   Seaweeds (like nori, kelp, kombu, and wakame)

o   Fish and shellfish

3. Add supplemental iodine. You can take a straight iodine supplement -- typically potassium iodide in pill or liquid form –or choose a multivitamin that includes the RDA of iodine.

Here are a few additional tips:

  • If you’re pregnant or trying to conceive, don’t assume that your prenatal vitamin includes iodine. Double-check the label; only 60% of prenatal vitamins include iodine, including those available by prescription.
  • Also, if you’re formula feeding your baby, double-check that the formula contains the required amount of iodine.

A note from Paloma

You should be aware that there’s some controversy around iodine supplementation for people with Hashimoto’s thyroiditis. The primary concern, however, is in megavitamin and high-dose iodine supplementation. Most patients don’t appear to have a problem when supplementing with iodine at levels that meet the RDA. Excessive iodine intake can, however,  worsen inflammation in autoimmune thyroid disease patients.  

As a thyroid patient, good health starts with good thyroid care. Start by using Paloma’s home thyroid test kit, which makes testing your levels of thyroid hormone convenient and easy to do at home. You can then schedule a virtual visit with one of Paloma’s knowledgeable thyroid practitioners. They will work with you to ensure that you are getting optimal thyroid treatment and relief of symptoms.

If you’re confused about how much iodine you need or want help determining how to incorporate more iodine into your daily diet, consider a session with one of Paloma’s expert thyroid nutritionists.

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Mary Shomon

Patient Advocate

Mary Shomon is an internationally-recognized writer, award-winning patient advocate, health coach, and activist, and the New York Times bestselling author of 15 books on health and wellness, including the Thyroid Diet Revolution and Living Well With Hypothyroidism. On social media, Mary empowers and informs a community of more than a quarter million patients who have thyroid and hormonal health challenges.

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