What is iodine? And what are iodine-rich foods?

What is iodine?

Iodine is the 53^rd element displayed on the Periodic Table. It is most commonly found within specific rigid structures (such as seaweed) as a solid trace element, though in day-to-day life it tends to be found as a non-edible solution in liquid form, such as the iodine seen in some antiseptics, or, alternatively, as an edible trace element within the food we eat. In terms of specific foods that contain iodine, seafood and dairy products are good sources, though iodine is also routinely added into table salt and bread in countries like Australia, to combat iodine deficiency.

What does iodine do?

Iodine is important within the body because it is intricately involved with thyroid gland function, which is paramount in maintaining body metabolism and hormonal balance. However, iodine also tends to have specific influences over the body, as seen in recent research.

Iodine deficiency during pregnancy

Iodine plays an important role in the development of the fetal brain, as seen in a recent UK study that has shown that maternal iodine deficiency during pregnancy impede a child’s reading capabilities and general IQ in early childhood [1]. In the ALSPAC study, a correlation was established between children with lower verbal IQ, reading accuracy and comprehension, and women with a mild-to-moderate deficiency in iodine [1]. The effect also appeared to be more profound as the deficiency in iodine increased in severity [1].

In another similar study, the children of mothers with mild to moderate iodine deficiency displayed significantly higher scores on the problem scales of inhibition and working memory, demonstrating impairment in executive functioning at the age of four [2]. This was in comparison to children of mothers with sufficient iodine status, who did not tend to display these issues [2].

And, yet another study showed that 9 year old children had significantly lower educational outcomes in spelling, grammar and literacy if their mothers had mild-moderate iodine deficiencies during pregnancy, as compared to children whose mothers had a sufficient iodine status during gestation [3]. This was observed despite all children having normal iodine levels at the time of the trial [3], which suggests that brain development in the first 1000 days requires iodine, and also that a deficiency during gestation can imbue long-term damage upon children, which in itself is not reversible by simply correcting the iodine deficiency later on.

Iodine deficiency in adults

Conversely, with regard to adults, the World Health Organisation suggests that iodine deficiency is linked to a decrease in productivity and can cause a human being to forfeit as many as 15 IQ points, due to the brain damage associated with deficiency. All of this information combined suggests that iodine levels must be kept in check from the moment of conception, and maintained throughout life, so as to ensure optimal growth and development in all stages of life.

References

1. Bath et al. Lancet. 2013 Jul 27;382(9889):331-7.
2. van Mil et al. J Nutr. 142(12): p. 2167-74.
3. Hynes et al. J Clin Endocrinol Metab. 98(5): p. 1954-62.