Published in the British Journal of Nutrition, the study found that the average pregnancy iodine intake without supplements was 190 microgram (μg) per day, falling well below the 250 μg recommended by the World Health Organisation (WHO).
Last year, the European Food Safety Authority (EFSA) proposed a new reference value of 200 μg per day as an adequate intake for pregnant women.
Meanwhile, in the UK the Reference Nutrient Intake for adults was 140 μg day, without any suggested increase for pregnant and lactating women.
Commenting on this UK advice, the researchers from the University of Glasgow said: “Current dietary recommendations in pregnancy, and their dissemination, are found not to equip women to meet the requirements for iodine intake.”
They looked at 1026 pregnant women and mothers with a child aged up to 36 months. Online electronic questionnaires were distributed across the UK between August 2011 and February 2012.
They found self-reported awareness about general nutritional recommendations during pregnancy was high (96%). Yet awareness of iodine-specific recommendations was low (12%), as was the level of confidence on how to achieve adequate iodine intake (28%).
While messages about folic acid and iron reached the women, mothers were not confident about their iodine intake in terms of good dietary sources or how to meet the adequate levels for pregnancy.
They said awareness of nutritional recommendations during pregnancy would “empower mothers to make the right dietary choices” leading to adequate iodine intake.
Crucial for neurodevelopment
The researchers described iodine as a key component of the thyroid hormones, which are crucial for neurodevelopment in the womb, infancy and beyond.
The UK population was described as mildly iodine-insufficient, while it was listed as the top eighth iodine-deficient country in the world by a 2012 paper.
“Adequate levels of iodine during pregnancy are essential for foetal neurodevelopment, and mild iodine deficiency is linked to developmental impairments,” the researchers wrote.
According to WHO, iodine deficiency affects 1.9 billion people globally and is the most preventable cause of intellectual disability.
Good food sources include sea fish and shellfish as well as some cereals and grains. Iodine supplements are also available but the UK's National Health Service (NHS) advices consumers not to take too much since this could be "harmful". Past research suggested that over supplementation with iodine during pregnancy could lead to the development of thyroid hormone deficiency (congenital hypothyroidism).
EFSA has authorised five health claims for iodine covering ‘normal thyroid function and production of thyroid hormones’, ‘maintenance of skin’, ‘normal cognitive and neurological function’ and ‘normal energy-yielding metabolism’ and ‘normal growth of children’.
Source: British Journal of Nutrition
Published online ahead of print, doi:10.1017/S0007114515001464
“Iodine and pregnancy – a UK cross-sectional survey of dietary intake, knowledge and awareness”
Authors: E. Combet, M. Bouga, B. Pan, M. E. J. Lean and C. O. Christopher