Excess maternal iodine linked to thyroid problems in newborns

By Nathan Gray

- Last updated on GMT

Related tags Thyroid Breastfeeding

Excess maternal iodine linked to thyroid problems in newborns
Over supplementation with iodine during pregnancy could lead to the development of congenital hypothyroidism in newborns, according new clinical case data.

The research paper – published in the Journal of Pediatrics – ​describes three infants who developed thyroid hormone deficiency (known as congenital hypothyroidism) as a result of excess maternal iodine supplementation.

Dr Kara Connelly of Oregon Health & Science University, USA, and colleagues reveal the details of three infants with congenital hypothyroidism whose mothers had taken 12.5 mg of iodine daily – more than 11 times the safe upper limit – while pregnant and/or breastfeeding.

"The use of iodine-containing supplements in pregnancy and while breastfeeding is recommended,”​ noted Connelly. “However, these cases demonstrate the potential hazard of exceeding the safe upper limit for daily ingestion."

Connelly and her colleagues called for increased attention a potential increase in the use of nutritional supplements containing iodine in amounts far higher than the recommended daily allowance during pregnancy: “The use of nutritional supplements is increasing in our society due to the belief that they are healthy and ​safe and can replace dietary deficiencies with minimal side effects.”

“The mothers of these three infants were ingesting a nutritional supplement whose iodine content far exceeded the daily recommended intake and had elevated iodine levels in urine and breast milk samples.”

Iodine excess

Connelly and her team revealed that the three infants had blood iodine levels 10 times higher than healthy control infants.

They added that although the World Health Organization (WHO) recommends 200-300 µg of iodine daily during pregnancy for normal fetal thyroid hormone production and neurocognitive development, 1,100 µg is considered to be the safe upper limit for daily ingestion by the US Institute of Medicine.

Globally congenital hypothyroidism is most commonly caused by a deficiency of iodine. However excess iodine may also be part of the explanation for the reported increasing incidence in recent years.

However, the team noted that because it is not routine practice to ask mothers of infants with congenital hypothyroidism about all nutritional supplements taken during pregnancy, the over-supplementation of iodine – leading to excess iodine – may be a more common practice than currently presumed.

Source: Journal of Pediatrics
Published online ahead of print, doi: 10.1016/j.jpeds.2012.05.057
“Congenital Hypothyroidism Caused by Excess Prenatal Maternal Iodine Ingestion”
Authors: K.J. Connelly, B.A. Boston, E.N. Pearce, D. Sesser, D. Snyder, et al​ 

Related news

Related products

show more

4 reasons children need MFGM, according to science

4 reasons children need MFGM, according to science

Content provided by Valio | 29-Sep-2023 | White Paper

In this white paper, Dr Anu Turpeinen discusses the ample scientific evidence showing why milk fat globule membrane (MFGM) is essential for children’s...

An Insights-driven Holistic Approach to Health

An Insights-driven Holistic Approach to Health

Content provided by Lipofoods, a Lubrizol Company | 25-Sep-2023 | Product Brochure

As they adopt the notion of holistic health, proactive consumers are driving the demand for products that have science-backed ingredients and offer sensory...

Introducing a new era in infant nutrition

Introducing a new era in infant nutrition

Content provided by dsm-firmenich | 01-Sep-2023 | Research Study

Omega-3s are critical to infant health and development – but conventional omega-3 ingredients are impacting the planet.

Related suppliers

2 comments

Seaweed and kelp

Posted by chris aylmer,

The iodine content of kelp and other foods and snacks containing seaweed preparations can be be way higher than the recommended dose. There seems to be no general awareness of this, nor any warnings on labels.

Report abuse

How about adult iodine supplmentation?

Posted by Roseane Santos,

There are some number of products targeting a pre-hypothyroidism population that comes with 12.5mg of iodine and 5.0mg of iodide. What is known about limits for those supplements in the normal adult population?

Report abuse

Follow us

Products

View more

Webinars