Wellington, Sept 8 NZPA - Exports have long known lack of iodine can retard children's mental development, but thought this and other effects only kicked in with moderate to severe deficiencies.

* Now Otago University researchers have now shown giving iodine to even mildly-deficient children can measurably improve their intelligence.

* Children given 150 micrograms of iodine daily "improved perceptual reasoning in mildly iodine-deficient children".

* A moderate lack of iodine can affect people both mentally and physically, making them people tired, overweight, constipated, and with goitre (an enlarged thyroid gland)..

* Severe deficiency can cause stunted growth, and mental retardation in children and damage hearing.

* Table salt has been iodised since 1924, with the dosage increased to 40-80mg per 1kg of salt since 1938.

* Nutrition surveys have shown mild levels of iodine deficiency in children aged 5-14, with 28 percent with low iodine status.

* Children born to iodine-deficient mothers risk having poorer verbal and information processing skills, lower levels of perceptual, mental and motor skills, and attention deficit and hyperactivity disorders.

* These children can grow up with a lower IQ, learning difficulties, reading difficulties, and hearing difficulties.

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