Iodine is an element that is essential for normal growth, and for brain development. A healthy diet needs enough iodine, but too much can cause health problems. As food hygiene practices have changed, and less people consume iodised salt, iodine deficiency is becoming more common in Australia. A radioactive form of iodine is sometimes used to treat certain thyroid conditions including hyperthyroidism and thyroid cancer — this is not the same as iodine found in food or dietary supplements.

Iodine helps the thyroid gland, in the neck, to make the hormone thyroxine. Thyroxine controls many of the ways certain body cells work. Thyroxine is important for the growth of bones and nerves, and affects how proteins, fats and carbohydrates are used in the body (metabolism). Iodine is especially important before birth and in babies and young children. It is essential for the development of the brain and nervous system, the 5 senses, alertness and coordination. Iodine deficiency is the most common worldwide cause of preventable mental retardation.

How do I get enough iodine?

You get iodine from the food you eat. Foods high in iodine include seafoods such as oysters, snapper and seaweed. Tinned salmon, bread, eggs, milk and dairy products such as yoghurt also contain iodine. Iodine is also added to many types of salt. You can check on the label whether salt is ‘iodised’ (has added iodine). Iodised salt is now used in commercial bread making, to help make sure all Australians get enough. The packaging will tell you how much iodine the bread contains.

If you are pregnant, it’s important to check if you are getting enough iodine. Low iodine levels can increase the risk of a miscarriage. It can also lead to poor growth and intellectual disability in the baby. The National Health and Medical Research Council recommends that anyone who is pregnant, breastfeeding or planning a pregnancy take an iodine supplement of 150 micrograms each day to top up their dietary intake. This will help ensure that they get all the iodine they need. Ask your doctor or pharmacist for more information. If you are pregnant, avoid kelp (seaweed) supplements as these may contain varying levels of iodine and may contain heavy metals such as mercury that can be problematic during pregnancy. If you have a thyroid condition, check with your doctor before taking an iodine supplement. Iodine supplements aren’t recommended for people with certain thyroid conditions.

Foods high in iodine

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Iodine and your health

Key facts

Iodine is a mineral that your body needs to make thyroid hormones.
Foods rich in iodine include seafood, dairy products and iodised table salt.
You should take an iodine supplement if you're planning a pregnancy, are pregnant or breastfeeding.
Too little iodine can cause iodine deficiency disorders and hypothyroidism.
Too little iodine during pregnancy is the most common cause of intellectual disability.

What is iodine?

Iodine is a mineral that your body needs to make thyroid hormones. Babies and young children need iodine for normal growth and for brain development.

Iodine is a critical nutrient for good health at all stages of life.

Why is iodine important for my health?

Your body needs thyroid hormones to make protein and for your metabolism.

Iodine is very important during pregnancy to make sure that your baby grows properly. Babies and children need iodine so that their bones and brains can develop properly.

Iodine deficiency during pregnancy is the most common cause of intellectual disability. Deficiency of Iodine during pregnancy and in early infancy can cause problems that last your baby's lifetime.

Radioactive iodine treatment is sometimes used to treat certain thyroid conditions. If you need this treatment, your doctor will help you change to a diet that's low in iodine.

Where does iodine come from?

Iodine is found in many foods such as:

seafood — fish and prawns
dairy products
eggs
packaged bread

Some parts of Australia have soils that are low in iodine. This affects the amount of iodine in any food grown and may increase your chance of being iodine deficient.

In Australia, iodised salt must be used in the manufacture of bread. This helps to lower rates of iodine deficiency.

Plant based milks do not normally contain iodine. Learn more about foods high in iodine.

How much iodine do I need?

How much iodine you need depends on your age.

Most adults need 150 micrograms of iodine a day. You need more iodine if you are pregnant or breastfeeding.

Iodine daily intake recommendations.
Stage of Life	Recommended dietary intake* of iodine (micrograms per day)
0-6 months	90
7-12 months	110
1-8 years	90
9-13 years	120
14-18 years	150
Adults	150
During pregnancy	220
While breastfeeding	270

*Recommended dietary intake (RDI): is the average daily dietary intake level that is needed to meet the nutrient requirements of nearly all (97–98%) healthy people in a certain life stage and gender group.

Can I have too little iodine?

Too little iodine can cause hypothyroidism (underactive thyroid). Symptoms of hypothyroidism are:

tiredness
constipation (difficulty pooing)
weight gain
depression

Goitre (a lump in your neck due to an enlarged thyroid gland) is less common.

Learn more about iodine deficiency.

Preparing for an appointment? Check our page on questions to ask your doctor for general tips on what to ask your GP or specialist.

Can I have too much iodine?

Too much iodine can cause the same symptoms as iodine deficiency, such as:

goitre
hypothyroidism
higher levels of thyroid stimulating hormone

Too much iodine can also cause:

hyperthyroidism
thyroiditis (when your thyroid is inflamed)
thyroid cancer

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Should I take iodine during pregnancy?

You should take an iodine supplement of 150 micrograms a day, when planning a pregnancy, pregnant or breastfeeding.

This helps your baby's brain and nervous system grow properly. Mild iodine deficiency has been linked to a lower intelligence quotient (IQ).

Iodine supplements aren't advised for people with some thyroid conditions. Check with your doctor, pharmacist or midwife before taking an iodine supplement.

Resources and support

Visit Nutrition Australia to learn more about iodine.
Read the NHMRC factsheet on iodine supplementation before conception, during pregnancy and while breastfeeding.
Pregnancy, Birth and Baby has information on vitamins and supplements in pregnancy.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.

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Last reviewed: April 2025

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