5.6.3 Iodine
Iodine is vitally important; it is required for the synthesis of maternal thyroid hormones, which,
in turn, are essential for the development of the fetal central nervous system. An adequate
intake of iodine should thus be assured before conception and during pregnancy and lactation.
Thyroid hormones are necessary for programmed, coordinated development of the child’s
central nervous system and cognitive and behavioural development; therefore, iodine deficit is
one of the preventable causes of developmental and mental disorders. The fetus is most
susceptible to iodine deficit during the early stages of pregnancy. If iodine supplementation is
given only after the first antenatal visit (ninth week), it is too late to ensure the best possible
outcome of the pregnancy.
To ensure an adequate intake of iodine before conception, women of reproductive age should
have a sufficient daily intake. The daily intake of iodine before conception and during
pregnancy and lactation should be 150–250 µg, which can be supplied by vitamin formulations
with potassium iodide as the active ingredient. The maximum dosage allowed for pregnant and
lactating women is 600 µg/day; a dosage > 1100 µg/day is deemed unsafe. The dosage should
be adjusted for women with a thyroid disorder, in consultation with an endocrinologist. Intake
of iodine with food depends on the iodine levels in food and soil, the use of iodine disinfectants
in the food industry and use of iodine-‐containing fertilizers in agriculture.
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The main sources of iodine in the diet are fish, seafood and dairy products. Use of iodized salt in
cooking food at home is important, as it is added to only a small proportion of processed foods
in Latvia. For most pregnant women, the intake of iodine from food is insufficient: iodized salt,
consumption of seafood twice a week and dairy products generally provide up to 100 μg/day;
therefore, an additional 100–150 μg of iodine are required, which should be taken as
supplements. Complex supplements containing folic acid and iodine are available for use when
planning a pregnancy. An expectant mother who is already taking multivitamin supplements
that contain the required amounts of iodine does not require additional supplementation.
Seaweed and algae supplements are not recommended during pregnancy, as they might result
in an overdose of iodine, with a negative impact on thyroid function.
Exclusively breastfed children receive an adequate supply of iodine if the mother’s intake is
adequate.
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