Portuguese pregnant women have mild to moderate iodine deficiency, which may compromise the neurological and cognitive development of babies. The conclusion is from a study conducted by researchers from CINTESIS – Center for Health Technology and Services Research / Faculty of Medicine of the University of Porto (FMUP), as part of the IoMum project, aiming to determine iodine levels during pregnancy.
In all, 481 pregnant women, with an average age of 32 years, living in the region of Porto, participated in this study for one year. Iodine levels were calculated from urine tests performed on the participants. The results indicate that the median iodine level was only 104 μg/L, well below 150 μg/L, the minimum adequate value during pregnancy. In 19% of the pregnant women, these levels were below 50 μg/l.
Published in the Journal of Endocrinological Investigation, this study reveals that 43% of pregnant women were not taking a supplement of iodine, which increases the risk of deficiency. Moreover, among the women who were taking this supplement, almost half started after the sixth week of gestation, contrary to what is recommended.
Since 2013, the Portuguese Directorate General of Health (DGS) has recommended iodine supplementation before getting pregnant (three months), during pregnancy and breastfeeding, with the World Health Organization (WHO) recommending a daily intake of 250 μg.
Lack of supplementation is a risk factor for developing a deficiency in this micronutrient. In this study, median iodine levels were only 74 μg/l in women who did not supplement. Pregnant women taking iodine supplementation, on the other hand, had median values of 146 μg/l.
“Pregnant women’s lack of adherence to supplementation is clearly related to iodine insufficiency. Not taking a supplement is associated with a six-fold increased risk of having iodine levels below what is adequate,” explains Elisa Keating, from FMUP/CINTESIS and coordinator of IoMum, and Cláudia Matta Coelho, PhD student at FMUP and first author of the study.
Previous studies from the same group indicate that about half of pregnant women do not recognize the importance of iodine intake for the normal neurocognitive development of their babies in utero and, among the women who know that iodine is essential during pregnancy, 32% cannot indicate any food rich in this nutrient.
It is not enough to know that iodine is important in pregnancy. Even pregnant women who recognize this importance have iodine amounts below what is advised. “Knowing that iodine is important during pregnancy may not be enough. It is urgent to promote actions to ensure that Portuguese women of childbearing age start their pregnancy with appropriate levels of iodine,” they warn.
For IoMum researchers, the findings of these studies should support the implementation of Public Health measures that include the promotion of milk consumption, which is also associated with increased iodine levels, and the use of iodized salt in food during pregnancy, and all these measures should be accompanied by active monitoring of iodine status in this vulnerable population.
“Portugal still has no salt iodization program, although more than 100 countries already have legislation in this area. Concerns about salt related to cardiovascular diseases should be counterbalanced with actions that lead the industry to adjust the concentrations of iodine in salt, and implementing measures to monitor the iodine status in the population. The recently established Associate Laboratory – RISE may address this monitoring need,” they indicate.
Italy appears as an example to follow. To compensate for the need to reduce salt in the diet, this country has increased the iodine content in salt (30 mg per kilogram of salt).
The IoMum project has the participation of dozens of researchers from several Higher Education Institutions in Portugal and other countries, and the University Hospital Center of São João, in Porto.