Iodine Deficiency affects IQ of Children

Insufficent iodine in the diet of some Irish women has put them at risk of having children with a lower IQ or even attention problems, according to the preliminary results of a new study published in Irish Journal of Medical Science.

A team of researchers at University College Dublin (UCD, have said that Irish women of childbearing age are not consuming enough iodine. This could adversely affect the development of their unborn foetus, the IQ of their children as well as play a role on the incidence of attention deficit hyperactivity disorder (ADHD)'.

Until 13 - 15 weeks gestation a developing foetus relies solely on the presence of the mother's thyroid hormones to ensure 'neuropsychological development' because its thyroid gland is not yet functional. Of course this supply of thyroid hormones is dependent on an adequate supply of iodine in the diet of the pregnant mother.

Iodine can be got from iodised salt, seafood such as white deep water fish and shellfish, dairy products and certain vegetables.

The researchers studied 54 women who were in the first trimester of their pregnancies and attending the National Maternity Hospital, Holles Street.

In addition the researchers also measured the iodine content of dairy milk on sale in Dublin at the time.

It was found that the dietary intake of iodine by Irish women is much lesser than the level recommended by the World Health Organisation. This problem only worsens in the summer months when available iodine in food sources like dairy milk is at its lowest.

The current findings have revealed that iodine intake by women of childbearing age has declined since the last findings in the mid-1990s when lead researchers, Dr Peter Smyth of UCD and Prof Colm O'Herlihy of Holles Street had carried out similar studies.

The researchers noted that Ireland and the UK are at the bottom of universal salt iodisation (USI) table with iodised salt making up just 3.3% of all salt sold here. Iodised salt has now become the primary dietary source of iodine in most countries worldwide where 60 - 90% of households use iodised salt.

Iodine in Irish diet is mainly based on dietary preference for iodine containing foods, such as seafood.

Dr Smyth said, "While there is as yet no available evidence of widespread under active thyroid function in the Irish obstetric population, the findings are a cause of concern. If confirmed by a more comprehensive investigation, this may indicate a need to increase the dietary iodine supply to both pregnant women and those of childbearing age."