What does iodine do in the body?

Iodine is required to make thyroid hormones, which help regulate metabolism, growth, and development. Adequate iodine is especially important during pregnancy and early childhood for brain development.

What are the best dietary sources of iodine?

Common sources include seafood, dairy products, eggs, and iodized salt. Iodine content can vary by food and local soil or farming practices.

How much iodine do adults typically need?

Many adult recommendations are around 150 mcg per day, and some people may use higher intakes under medical guidance. Needs can differ during pregnancy and breastfeeding.

What are signs of iodine deficiency?

Deficiency can lead to an enlarged thyroid (goiter) and low thyroid function. During pregnancy and infancy, inadequate iodine can impair normal growth and neurodevelopment.

Can you get too much iodine?

Yes—excess iodine can trigger thyroid dysfunction in some people, including hypothyroidism or hyperthyroidism. People with thyroid disease should discuss iodine supplements with a clinician.

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Iodine

Strong study situation·10/10

A higher score indicates better study conditions, but not necessarily effectiveness.

Iodine is an essential trace mineral, critical for thyroid hormone production, cognitive development, and metabolic health.

Eye Health Motherhood Cognitive Enhancement Essential Nutrient Bone Health Hormone Balance

dose range

150–300 µg

Once daily with food

Consumption

Take once daily, ideally with food to reduce gastrointestinal upset.

Not fat-soluble.

Best time

Taking with the first or second meal is standard.

Description

Iodine is a vital micronutrient required for the synthesis of thyroid hormones, which regulate metabolism, growth, and development. It is naturally found in seafood, dairy products, eggs, and iodized salt. Adequate iodine intake is especially important during pregnancy and infancy to support fetal and neurological development.

benefits

Main effects with level of evidence

Strong

Note on evidence

Evidence for iodine’s role in preventing deficiency disorders and supporting neurodevelopment is robust. Excess intake risks are well documented.

Supports healthy thyroid function

Strong

Iodine is essential for the synthesis of thyroid hormones, which regulate metabolic rate and energy balance.

Particularly relevant for: General · Pregnant women · Infants · Children

ODS · NIH Office of Dietary Supplements: Iodine Fact Sheet EFSA · EFSA: Tolerable upper intake level for iodine WHO · WHO: Iodine Status Worldwide

Prevents iodine deficiency disorders (IDD)

Strong

Reduces risk of goiter, hypothyroidism, mental impairment, and congenital abnormalities associated with deficiency.

Particularly relevant for: General · Pregnant women · Infants · Children

ODS · NIH Office of Dietary Supplements: Iodine Fact Sheet WHO · WHO: Iodine Status Worldwide Cochrane · Iodine supplementation for preventing iodine deficiency disorders in children

Critical for cognitive development in infants and children

Strong

Iodine sufficiency supports neurological development and IQ; deficiency during pregnancy or early life can impair cognitive outcomes.

Particularly relevant for: Pregnant women · Infants · Children

ODS · NIH Office of Dietary Supplements: Iodine Fact Sheet WHO · WHO: Iodine Status Worldwide Cochrane · Iodine supplementation for preventing iodine deficiency disorders in children

Safety & Information

Important safety information & known risks

For educational purposes only • not medical advice

Iodine is safe in recommended doses but excess intake can disrupt thyroid function and may be harmful in people with pre-existing thyroid conditions.

warning notices

Excessive intake can trigger hypothyroidism, hyperthyroidism, or thyroiditis, especially in those with thyroid autoimmunity.
Acute toxicity from very high doses is rare but can cause gastrointestinal and neurological symptoms.
People with autoimmune thyroid disease should use with medical supervision.
Avoid iodine supplements if you have autoimmune thyroid disease unless directed by a healthcare provider.
Do not use high-dose iodine if you are taking antithyroid medications due to risk of thyroid dysfunction.
Monitor thyroid function when taking iodine supplements with lithium or ACE inhibitors.

Known interactions with medications