Iodine is an essential mineral that plays a critical, albeit often understated, role in human health. Naturally present in certain foods, iodine is indispensable for the synthesis of thyroid hormones. These hormones are the master regulators of your body’s metabolism, orchestrating a vast array of bodily functions. Beyond metabolism, thyroid hormones are paramount for proper bone and brain development, particularly during the crucial stages of pregnancy and infancy. Ensuring adequate iodine intake is therefore vital for everyone, and especially critical for pregnant women and infants.
How Much Iodine Do You Need Daily? Understanding Recommended Intake
The daily iodine requirement varies depending on age and life stage. The following table outlines the average daily recommended amounts, measured in micrograms (mcg):
| Life Stage | Recommended Amount (mcg) |
|---|---|
| Birth to 6 months | 110 |
| Infants 7–12 months | 130 |
| Children 1–8 years | 90 |
| Children 9–13 years | 120 |
| Teens 14–18 years | 150 |
| Adults | 150 |
| Pregnant teens and women | 220 |
| Breastfeeding teens and women | 290 |
Dietary Sources of Iodine: Where to Find It in Your Food
Iodine is naturally occurring in various foods and is also commonly added to table salt, creating iodized salt. By incorporating a diverse range of foods into your diet, you can readily meet your recommended daily iodine intake. Excellent food sources of iodine include:
- Seafood: Fish like cod and tuna, seaweed, shrimp, and other marine delicacies are generally abundant in iodine.
- Dairy and Eggs: Dairy products such as milk, yogurt, and cheese, along with eggs, contribute significantly to iodine intake.
- Iodized Salt: A readily available source in many countries, including the United States.
It’s important to note that processed foods, such as canned soups, typically do not contain iodized salt. Furthermore, specialty salts like sea salt, kosher salt, Himalayan salt, and fleur de sel are usually not iodized unless specifically stated on the product label. Always check product labels to confirm if a salt is iodized or provides iodide.
Image alt text: A colorful array of iodine-rich foods, featuring fish, dairy products like milk and cheese, seaweed, and eggs, highlighting diverse dietary sources of this essential mineral.
Iodine Supplements: Exploring Available Options
For individuals seeking to supplement their dietary iodine intake, various iodine dietary supplements are available. These supplements commonly contain iodine in the forms of potassium iodide or sodium iodide. Many multivitamin and mineral supplements also incorporate iodine. Additionally, supplements derived from kelp, a type of seaweed naturally rich in iodine, are also accessible.
Are You Getting Enough Iodine? Assessing Your Intake
While iodine deficiency is relatively uncommon in the United States, certain populations are at a higher risk of insufficient iodine intake. These groups include:
- Non-users of Iodized Salt: Iodizing salt is a globally recognized strategy to combat iodine deficiency. However, a portion of the population may not consistently use iodized salt.
- Pregnant Women: Due to increased needs for both themselves and their developing baby, pregnant women require approximately 50% more iodine than non-pregnant women. Surveys suggest that some pregnant women in the US may not be meeting these elevated requirements.
- Vegans and Those Limiting Dairy, Seafood, and Eggs: Individuals adhering to vegan diets or those who limit their consumption of dairy, seafood, and eggs – all significant iodine sources – may face a higher risk of deficiency.
- Populations in Iodine-Deficient Regions: People residing in regions with iodine-poor soils, who primarily consume locally grown foods, may have lower iodine intake as crops grown in these soils have reduced iodine levels. Mountainous regions like the Himalayas, Alps, and Andes, and river valleys in South and Southeast Asia are examples of such areas.
- Individuals Consuming Goitrogenic Foods with Marginal Iodine Intake: Goitrogens are substances found in certain plant foods, including soy and cruciferous vegetables (cabbage, broccoli, cauliflower, Brussels sprouts), which can interfere with iodine utilization by the body. For those with adequate iodine intake, moderate consumption of goitrogenic foods is generally not a concern. However, for individuals with marginal iodine levels, these foods could exacerbate deficiency.
Image alt text: A woman in a grocery store aisle carefully selecting iodized salt, emphasizing the importance of choosing iodized salt to ensure adequate iodine intake for thyroid health.
Consequences of Iodine Deficiency: Understanding the Risks
Iodine deficiency, though not widespread in developed nations like the US and Canada, can lead to serious health issues. Insufficient iodine hinders the body’s ability to produce adequate thyroid hormones, resulting in a range of problems. In pregnant women, severe iodine deficiency poses a significant threat to the fetus, potentially causing irreversible harm including stunted growth, intellectual disabilities, and delayed sexual development. Even milder iodine deficiency during pregnancy can negatively impact infant and child IQ levels and impair cognitive function in adults. Goiter, an enlargement of the thyroid gland, is often the most visually apparent sign of iodine deficiency.
Health Benefits of Iodine: Beyond Thyroid Function
Ongoing research continues to explore the broader health implications of iodine beyond its well-established role in thyroid hormone production. Key areas of investigation include:
Fetal and Infant Development: Ensuring Healthy Beginnings
Adequate iodine intake during pregnancy and breastfeeding is paramount for optimal fetal and infant growth and development. Breastfed infants obtain iodine from breast milk, and the iodine content of breast milk is directly influenced by the mother’s iodine intake.
Recognizing the critical importance of iodine for fetal and infant development, numerous national and international health organizations recommend iodine supplementation for pregnant and breastfeeding women, as well as infants. The American Thyroid Association, for instance, advises women who are pregnant, planning pregnancy, or breastfeeding to take a daily supplement containing 150 mcg of iodine as potassium iodide. The American Academy of Pediatrics echoes this recommendation. However, it’s noteworthy that only approximately half of prenatal multivitamins available in the United States contain iodine.
Cognitive Function in Childhood: Supporting Brain Development
Severe iodine deficiency during childhood has demonstrably detrimental effects on brain and nervous system development. The impact of mild iodine deficiency is more subtle but is hypothesized to potentially contribute to subtle neurological developmental issues.
Studies indicate that providing iodine supplements to children with mild iodine deficiency can improve reasoning skills and overall cognitive function. In iodine-deficient regions, iodine supplementation appears to positively influence both physical and mental development in children. Further research is ongoing to fully elucidate the long-term effects of mild iodine deficiency and the benefits of iodine supplementation on cognitive function.
Fibrocystic Breast Disease: Potential Relief with Iodine?
Fibrocystic breast disease, while benign, can cause breast lumps and pain, predominantly affecting women of reproductive age and sometimes persisting through menopause. While still under investigation, some studies suggest that very high doses of iodine supplements might alleviate pain and other symptoms associated with fibrocystic breast disease. However, this remains an area of ongoing research, and it is crucial to consult with a healthcare provider before considering iodine for this condition, particularly given the potential risks of high iodine doses.
Radiation-Induced Thyroid Cancer: Protective Role of Iodine
Nuclear accidents can release radioactive iodine into the environment, significantly elevating the risk of thyroid cancer, especially in children exposed to radioactive iodine. Individuals with pre-existing iodine deficiency are particularly vulnerable. Potassium iodide has been approved by the U.S. Food and Drug Administration (FDA) as a thyroid-blocking agent in radiation emergencies. Potassium iodide works by saturating the thyroid gland with stable iodine, preventing the uptake of radioactive iodine and thereby reducing the risk of radiation-induced thyroid cancer.
Low Iodine Diets for Radioactive Iodine Treatment: Preparing for Therapy
Radioactive iodine therapy is a treatment modality for certain types of thyroid cancer. To optimize the effectiveness of this treatment, patients are typically instructed to adhere to a low iodine diet (50 mcg or less per day) for 1 to 2 weeks prior to treatment initiation. This dietary restriction aims to deplete the body’s iodine stores, making the thyroid gland more receptive to the radioactive iodine treatment.
Foods to be avoided on a low iodine diet include:
- Iodized salt
- Seafood, liver, seaweed, milk and milk products, and eggs
- Bread made with iodate dough conditioners
- Maraschino cherries and certain red or pink beverages potentially containing iodine-based red dyes
- Kelp-containing dietary supplements and many multivitamin/mineral supplements (always check Supplement Facts labels)
Foods generally considered low in iodine and permissible on a low iodine diet include:
- Non-iodized salt
- Fruits and fruit juices, vegetables, beans, and nuts
- Plant-based milk alternatives (soy and almond milk)
- Rice, pasta, and oatmeal
- Poultry, pork, and beef (excluding liver)
- Bread without iodate dough conditioners
Image alt text: A helpful table contrasting foods high in iodine, which should be limited or avoided by individuals on a low iodine diet, with foods low in iodine that are suitable for consumption during such dietary restrictions.
Iodine Overconsumption: Potential Risks and Upper Limits
While essential, excessive iodine intake can also be detrimental to health. High iodine levels can paradoxically trigger symptoms resembling iodine deficiency, including goiter. Furthermore, excessive iodine can lead to thyroid gland inflammation and, in some instances, thyroid cancer. Extremely high doses of iodine (several grams) can induce severe adverse effects such as burning sensations in the mouth, throat, and stomach, fever, abdominal pain, nausea, vomiting, diarrhea, weak pulse, and even coma.
The established daily upper limits for iodine intake from all sources (food, beverages, and supplements) are outlined below. These limits do not apply to individuals under medical supervision taking iodine for specific medical conditions.
| Life Stage | Upper Limit (mcg) |
|---|---|
| Birth to 12 months | Not established |
| Children 1–3 years | 200 |
| Children 4–8 years | 300 |
| Children 9–13 years | 600 |
| Teens 14–18 years | 900 |
| Adults | 1,100 |
Iodine Interactions: Medications and Other Supplements
Iodine supplements can potentially interact with certain medications. Examples of such interactions include:
- Antithyroid medications: Iodine supplements can interfere with the effectiveness of medications used to treat hyperthyroidism (overactive thyroid).
- ACE inhibitors: Concurrent use of iodine supplements and ACE inhibitors (used to manage high blood pressure) may increase the risk of hyperkalemia (high potassium levels).
- Diuretics: Certain diuretics, particularly potassium-sparing diuretics, taken with iodine supplements could also elevate the risk of hyperkalemia.
It is crucial to inform your doctor, pharmacist, and other healthcare providers about all dietary supplements and prescription or over-the-counter medications you are taking. They can assess potential interactions and advise on safe and appropriate use. They can also determine if your medications might affect iodine absorption or utilization in the body.
Iodine and a Healthy Diet: Prioritizing Food Sources
The Dietary Guidelines for Americans emphasize obtaining the majority of nutrients from food and beverages. Whole foods provide a complex array of vitamins, minerals, dietary fiber, and other beneficial compounds. While fortified foods and dietary supplements can be valuable in specific situations, such as pregnancy, meeting nutrient needs through a balanced dietary pattern is generally recommended. For comprehensive guidance on building a healthy dietary pattern, consult the Dietary Guidelines for Americans and MyPlate resources from the U.S. Department of Agriculture.
Further Information on Iodine: Expanding Your Knowledge
For more in-depth information about iodine, refer to our health professional fact sheet.
Disclaimer
This information sheet from the National Institutes of Health (NIH) Office of Dietary Supplements (ODS) is intended for informational purposes and should not be considered medical advice. Always consult with your healthcare providers (doctor, registered dietitian, pharmacist, etc.) regarding dietary supplements and their suitability for your individual health needs. Mention of specific products, services, organizations, or professional societies in this publication does not constitute endorsement by the ODS.
Updated: May 1, 2024 History of changes to this fact sheet
