Iodine
Needed to make thyroid hormones that guide growth and metabolism.
Why it matters
Iodine is required to make thyroid hormones, which influence growth, brain development, temperature regulation, and metabolism.
- Helps make thyroid hormones.
- Supports normal growth and brain development.
- Influences metabolism and temperature regulation.
If intake is too low
Low iodine can lead to goiter and hypothyroidism. During pregnancy, deficiency can impair fetal brain development.
- Goiter and low thyroid function.
- Fatigue, weight gain, or feeling cold when thyroid hormone drops.
- Pregnancy-related deficiency can affect fetal brain development.
If intake is too high
Too much iodine can also disrupt thyroid function. Very high intakes can trigger goiter, hypothyroidism, or hyperthyroidism in susceptible people.
- Can worsen or trigger thyroid dysfunction.
- Seaweed or kelp products can deliver very large amounts.
- Too much is not safer just because iodine is essential.
Adult upper limit: 1,100 mcg/day
Iodine has a real upper limit because both too little and too much can disturb thyroid function.
Common food sources
Iodine comes from iodized salt, seafood, dairy foods, and some fortified products.
- Iodized table salt
- Seafood, seaweed, dairy foods, and eggs
- Some multivitamins and prenatals that include iodine
Who may need closer attention
Low iodine intake is more likely when iodized salt, seafood, and dairy foods are all limited.
- People who are pregnant or breastfeeding
- People who avoid seafood and dairy and do not use iodized salt
- Anyone using kelp or seaweed products that may overshoot intake
Use extra caution if
Small details change the risk picture with nutrients more than most people expect.
You are pregnant, avoid seafood and dairy, use only non-iodized specialty salts, or take kelp-based supplements. Iodine status often depends on habits people do not realize are relevant.
Supplement and label notes
Useful context when this nutrient shows up across more than one product.
- Kelp products can vary widely in iodine content.
- Not every prenatal includes iodine, so labels are worth checking.
- If you have thyroid disease, do not assume more iodine is helpful.
Daily Value targets in SuppMap
These are the same label-style Daily Value targets used in the app.
Official references
These pages were used to draft the summaries on this guide.
Educational only. These pages are not a diagnosis or a substitute for personal medical care.
More guides
Keep moving through the rest of the Daily Value chart from here.