Iodine – Everything you need to know
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The following article provides the most important facts about iodine. Here you'll learn what iodine actually is, how much iodine your child needs, which foods contain iodine, and when you might need to supplement.
Iodine is a trace element and essential for the production of thyroid hormones. We humans obtain iodine through our diet.
Typical sources of iodine include fish, seafood, dairy products, bread and baked goods, and iodized table salt. Dairy products have a high iodine content because the cows' feed is supplemented with iodine. Bread is only rich in iodine if iodized table salt is used in its production. Vegetables such as broccoli, spinach, and kale also contain iodine, but only in small amounts.
Iodine Intake in Germany:
Approximately 30% of adults and almost 45% of women of childbearing age do not have sufficient iodine intake. This was revealed in the German Health Interview and Examination Survey for Adults (DEGS) with nearly 7,000 participants in 2011.
Unfortunately, the situation is no better for children and adolescents: The large second study on the health of children and adolescents, with nearly 3,400 participants, showed that almost 44% of children and adolescents do not consume enough iodine.
How can I recognize an iodine deficiency?
An iodine deficiency leads to the thyroid gland not being able to produce sufficient thyroid hormones. These are particularly important for body growth and the regulation of important metabolic processes. A lack of thyroid hormones can cause fatigue, difficulty concentrating, weight gain, and impaired growth. It can also lead to a condition called goiter, an enlargement of the thyroid gland. In very young babies, an iodine deficiency is not immediately noticeable, but can lead to impaired mental development and reduced intelligence.
The following table provides an overview of the amounts of iodine in some foods.
Foods: Average Iodine Content in μg/100 g
Iodized Table Salt: 1,500 – 2,500
Hadfish: 243
Pollock: 200
Lobster: 185
Shrimp: 130
Cod: 94
Hard Cheese: 40 – 80
Semi-Semi Cheese: 10 – 30
Milk and Dairy Products: 10 – 15
Broccoli: 15
Spinach: 12
Egg: 8 – 10
Rye Bread: 8.5
Iodine requirements are increased during certain phases of life, particularly during pregnancy, breastfeeding, and growth spurts. Even during pregnancy, mothers should ensure adequate iodine intake to avoid unnecessarily increasing the risk of premature birth and miscarriage. Even mild iodine deficiency during pregnancy or after birth carries the risk of hypothyroidism in the newborn, which can be associated with impaired brain development. This can potentially lead to hearing loss, cognitive deficits, and neuropsychological developmental disorders.
Therefore, the German Nutrition Society (DGE) recommends a 15% increase in iodine intake during pregnancy and breastfeeding.
The German Nutrition Society (DGE) recommends the following amounts of iodine depending on age:
Age µg/day
0 to under 4 months 40
4 to under 12 months 80
1 to under 4 years 100
4 to under 7 years 120
7 to under 10 years 140
10 to under 13 years 180
13 to under 15 years 200
15 to under 19 years 200
19 to under 25 years 200
25 to under 51 years 200
51 to under 65 years 180
65 years and over 180
Pregnant women 230
Breastfeeding women 260
How do I know if and how much iodine I should supplement?
Unfortunately, there are no official recommendations for iodine supplementation. The German Nutrition Society (DGE) only publishes reference values and indicates the recommended total intake. Therefore, if in doubt, it is always advisable to consult a doctor.
Here's a general guideline:
• In Germany, iodized table salt is one of the best sources of iodine. Therefore, when buying salt, make sure it is iodized.
• Adults who eat a balanced diet that includes fish, dairy products, and iodized table salt are very likely to get enough iodine.
• Pregnant women following a vegan diet should take 100-150 μg of iodine daily.
• Breastfeeding women are also advised to take 100-150 μg of iodine daily. Unfortunately, statutory health insurance companies do not cover iodine supplements.
• Breastfed babies get enough iodine from breast milk, provided the mother has sufficient iodine levels. Formula-fed babies get iodine from formula, which is fortified with sufficient amounts of iodine.
• As soon as infants start eating complementary foods and consume less milk or formula, their iodine intake changes. This depends on the amount of milk consumed and the complementary foods and their ingredients.
• Ready-made infant formula (milk substitute) usually contains added iodine, so bottle-fed infants generally don't have a problem with iodine intake. Some special baby foods, such as baby cereal flakes, are often fortified with iodine. Typical baby food jars for babies in their first year are unsalted and therefore only contain the amount of iodine naturally present in the ingredients. Baby food jars for babies over one year old usually contain iodized salt and therefore have a slightly higher iodine content. Iodine supplementation can thus be beneficial from the start of complementary feeding, as the recommended minimum intake is generally not met through diet alone. Anyone wanting to know their exact iodine intake should calculate it based on the food consumed and supplement accordingly if necessary.
• The following example could serve as a basis for an estimate: Breast milk (BM) should contain at least 5 μg of iodine per 100 ml. A baby still drinking 500 ml of BM thus ingests 25 μg of iodine through the milk, leaving at least 55 μg of iodine that must be obtained from other sources.
• Infants should receive a total of 80 μg of iodine daily from the age of 5 months.
• After the first birthday, the high iodine requirement hardly changes, but more and more iodine is now also ingested through complementary foods. Children who consume milk and cheese, occasionally fish, and regularly bread products with iodized table salt generally do not need additional iodine. For children on a vegan diet, iodine supplementation of 60-80 μg daily is certainly advisable.
The Connection Between Newborn Screening and the Thyroid Gland
In Germany, congenital hypothyroidism is detected through newborn screening. Children identified through this screening require lifelong thyroid hormone replacement therapy. This applies even to children who consume sufficient iodine, because the problem lies with the thyroid gland itself, not with iodine intake. If the thyroid gland is not functioning efficiently, even a simple iodine deficiency is not detected by the screening. However, the symptoms of iodine deficiency and congenital hypothyroidism in newborns are similar. The babies exhibit poor feeding, fatigue, and lethargy. If detected early, this condition can be treated effectively.
H. Heseker and B. Heseker, The Nutritional Value Table, 6th ed. Wiesbaden, 2021.
P. R. Pehrsson et al., “Iodine in food- and dietary supplement-composition databases,” Am. J. Clin. Nutr., vol. 104, no. Suppl 3, pp. 868S–876S, Sep. 2016, doi: 10.3945/ajcn.115.110064.
Robert Koch Institute – RKI (ed.) (2015) Health in Germany. Federal Health Reporting. RKI, Berlin
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