Iodine in pregnancy: why it must not be missing in a mother's diet

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Catherine Le Nevez
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Lo iodine it is an essential micronutrient essential for the proper functioning of the thyroid. There thyroid it is an endocrine gland located in the neck and only in the presence of iodine synthesizes the thyroid hormones responsible for various functions by regulating, for example, energy metabolism, body temperature, the accumulation of calcium ions in the bone tissue, the activity of the hypothalamus and pituitary gland. Pregnant thyroid hormones play a very important key role: they stimulate the development of the nervous system of the fetus. Their lack leads to a pathology that takes the name of cretinism, irrecoverable, characterized by intellectual and cognitive deficits. One in three women does not know that the need for iodine has almost doubled during pregnancy!

Where is iodine found in Del Paese

Iodine is naturally present in the soil and with the passing of millennia and geological eras, through the rains it has been distributed to seas and rivers. The evaporation of water allows its passage into the atmosphere and its subsequent return to the ground during atmospheric precipitation. Its quantity in food depends on its concentration in the soil which varies from area to area: there are many areas in the world where this trace element is scarce, not only in the mountainous areas but also in the plains and on the coast.

The country is a geographical area where iodine is present in insufficient quantities.

Iodine in pregnancy, smarter babies

How iodine is taken. The right nutrition

Iodine is taken with food, but its concentration varies greatly from food to food and from area to area. Crustaceans, sea fish and algae are particularly rich in them; while milk, meat, eggs, cereals, legumes, fruit and vegetables contain low quantities (depending on the soil in which the animals were grown or raised).

Average iodine content in food

  • Marine fish: 1.2 -2.5 mg / kg
  • Molluscs: 0.8 - 1.6 mg / kg
  • Marine algae: 20 - 8000 mg / kg
  • Sale marino: 1.4 mg/kg
  • Cow's milk: 50-200 μg / L
  • Eggs: 70-90 μg / kg
  • Meat: 50 μg / kg
  • Cereals: 47 μg / kg
  • Freshwater fish: 30 μg / kg
  • Legum: 30 μg / kg
  • Vegetables: 29 μg / kg
  • Fruit: 18 μg / kg

The iodized salt: how much per day

Often the iodine introduced in the diet is not sufficient to reach the daily requirement. To this end, in order to prevent pathologies related to iodine deficiency, from 5 May 2005 (Law 21 March 2005, n ° 55) in Del Paese, in addition to common salt, the sale of iodized salt is mandatory and must be available in bars, restaurants and collective catering places (canteens) and can be used in the preparation and storage of food products. According to the WHO, at least 90% of families should use iodized salt, but currently the data show that 57% of families use it regularly, 19% occasionally while 23% say they have never used it.

In almost all of Europe, a daily consumption of iodized salt of about 3-5 grams is recommended, providing together with the foods introduced in the diet a daily amount of iodine equal to 90-150 μg sufficient to guarantee an adequate intake of this important micronutrient, reducing at the same time the negative impact of excessive consumption of salt (sodium chloride) on arterial pressure and cardiovascular diseases.

During pregnancy and breastfeeding, supplements are necessary to reach the recommended daily doses with a positive effect on the development of the thyroid functions and the cognitive and psychomotor abilities of the child, confirmed by a recent study published in the European Journal of Endocrinology involving Del Paese, Denmark , Belgium, Germany and Spain.

According to experts, a cup of milk a day would help to get a good amount of iodine and after weaning it is important to use iodine-rich foods such as sea fish at least twice a week; while after the first year of life you can also start seasoning foods with a moderate amount of iodized salt. (Also Read: Iodized Salt in Pregnancy)

Daily requirement

The daily need for iodine in adults is approximately 150 micrograms per day (μg / day), but during pregnancy it rises to 200-250 μg/die reaching i 290 μg/die while breastfeeding. These values ​​represent the Recommended Dietary Allowace (RDA) and have been decided by the World Health Organization in agreement with the main international institutions (AMA, NIH National Research Council, Joint UN FAO / WHO Expert Committee on Food Additives , and the EU IPCS).

RDA in age groups (μg / day)

- 0-6 months -> 110

- 7-12 months -> 120

- 1-8 years -> 90

- 9-12 years -> 120

- 12 up -> 150

- In pregnancy -> 220

- Breastfeeding -> 290

Things worth knowing about iodine:

- Cooking reduces the iodine content. Observations show a reduction of 20% with frying, 58% with boiling and 23% with cooking. - There are several foods enriched in iodine (potatoes, carrots…). - Some medications contain excess iodine (eg amiodarone) as well as slimming and anti-cellulite treatments containing algae.

Iodine deficiency: brain development and IQ at risk

Iodine deficiency is the main cause of goiter due to the increase in the size of the thyroid gland, with harmful effects on the body indicated as a whole "iodine deficiency disorders". The minimum amount to prevent goiter is about 50-75 μg / day.


  • Particularly sensitive to iodine deficiency is the nervous system of the unborn child. The brain begins to develop around the 3rd-4th week with the appearance of the neural tube under the action of thyroid hormones. The fetus begins to produce its own thyroid hormones only from the 12th week, so in the 1st trimester the proper development of the brain and organs depends on the mother's thyroid hormones passing through the placenta. A study conducted by the University of Bristol and Surrey, published in The Lancet, highlighted how an inadequate intake of iodine during pregnancy can damage the IQ (IQ) of the unborn child.
  • Feeding time.

    Even during breastfeeding, the mother must provide her baby with an adequate amount of iodine for proper thyroid function. Pregnancy and childhood are the stages of life in which even slight iodine deficiencies can cause serious, irreversible damage. The risk for infants is very high: their need for iodine in relation to body weight is greater than that present in any other age.
  • Childhood.

    Children with iodine deficiency, often born to mothers who did not take the correct amounts of iodine, in addition to goiter may have decreased IQ if the deficiency is mild, and hypothyroidism and cretinism if severe.

In this regard, the World Health Organization recommends that women of childbearing age use iodized salt consistently and regularly and resort to any supplementation both before and during gestation, in relation to diet and geographical area.

Iodine deficiency disorders

In pregnancy: miscarriage, congenital anomalies, death at birth, cretinism;
In the newborn: hypothyroidism and neonatal goiter;
In the adolescent: goiter, juvenile hypothyroidism, mental retardation and growth retardation;
In the adult: goiter and its complications, hypothyroidism, intellectual deficit.

Iodine yes, but not too much!

The European Scientific Commissions and the US Institute of Medicine recommend not to exceed with iodine supplementation. The observations show that taking 1 mg / day of iodine is excessive and harmful, especially during pregnancy and breastfeeding. Researchers from Oregon University in their study published in the Journal of Pediatrics, highlight how excessive consumption of iodine during pregnancy leads to a temporary block of normal thyroid functions and iodine levels in the unborn child's blood 10 times higher than normal.

In adults and older children, the block of thyroid functions decreases after a few weeks, while in newborns and fetuses, where the thyroid is not yet developed, the risk is of permanent damage to the thyroid gland with consequent development of hypothyroidism. The use of supplements containing iodine, especially during pregnancy and breastfeeding, must be done under careful medical supervision, in order not to exceed the safety limit set by the World Health Organization. (Read also: Nutrition during pregnancy, allowed foods and prohibited foods)

Sources: Sarah C Bath, Colin D Steer, Prof Jean Golding, Pauline Emmett, Prof Margaret P Rayman - Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: results from the Avon Longitudinal Study of Parents and Children (ALSPAC) – The Lancet Volume 382, No 9889, p331-337, 27 July 2022

Maria José Costeira, Pedro Oliveria, Nadine Correia Santos, Susana Ares, Belen Saenz-Rico, Gabriella Morreale de Escobar, Joana Almeida Palha - Psychomotor Development of Children from an Iodine-Deficient Region - The Journal of Pediatrics

Sarah S. Long - Iodine deficiency during pregnancy - The Journal of Pediatrics

European Journal of Endocrinology

Kara J. Connelly, Bruce A. Boston, Elizabeth N. Pearce, David Sesser, David Snyder, Lewis E. Braverman, Sam Pino, Stephen H. La Franchi - Congenital Hypothyroidism Caused by Excess Prenatal Maternal Iodine Ingestion – The Journal of Pediatrics



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