Iodine Deficiency

Introduction

Iodine (I) is an essential micro-mineral that is required for the growth and development of the human body and brain. It is also referred as a trace element along with zinc, copper, cobalt, chromium, manganese, molybdenum and selenium as these minerals are required by the body in <100 mg/day through diet (WHO Expert Committee on Trace Elements in Human Nutrition & World Health Organization, ‎1973). In the year 1811, this element was discovered by a French scientist Bemard Courtois, and later named after a Greek word ‘iodes’ meaning ‘violet coloured’ by a French chemist Joseph Louis Gay- Lussac. This appears as black, crystalline solid and shiny and when heated, iodine sublimes to form a purple vapour (Royal Society of Chemistry, n.d.).

Iodine is necessary to synthesize the thyroid hormones by thyroid cells, i.e., thyroxine (T4) and tri-iodothyronine (T3) that helps in synthesis of proteins and enzymatic activities in the body. Further, these hormones play a vital role in regulating the body’s large numbers of metabolic functions, for proper bone and brain/neuro development of fetus

Figure 1.

Functions of iodine

during pregnancy as well as during infancy and supports in many other important organ and body functions including heart, kidneys, pituitary gland, muscles and brain (Figure-1). Iodine deficiency during pregnancy and early childhood days is one of the extreme source of intellectual retardation among children which is purely preventable with iodine supplementation. A healthy adult body contains around 15–20mg of iodine and out of which almost 70%-80% are present in the organic form as iodothyroglobulin in thyroid gland of neck and the remaining 20%-30% stored in other bodily tissues such as salivary glands, blood, ovaries and muscles. Most of these iodine are present as Protein Bound Iodine (PBI) which represent the iodine level in the body with a usual range of 4-6 mg of iodine per deciliter of serum. With lack of iodine, there is a high chance of improper action of thyroid gland, causing various adverse side effects including Iodine Deficiency disorders (IDD) and medical conditions such as goiters, hypothyroidism and hyperthyroidism, which affects people of all age group [The Nutrition Source, Iodine, Havard T.H. Chan, School of public Health]. Apart from human beings, animals can also develop goiters due to iodine deficiency which is very much visible in dogs, cattle, goats, birds and fish (Zimmermann, 2009; De Benoist et al., 2007; NIH, n.d.; Degroot et al., 2007).

Today, people in many parts of the world still do not have enough iodine and iodine deficiency continues to be a public health problem. About 30% of the people in the world are at risk of iodine deficiency. As per the global estimation, around 2 billion people are affected by IDD. This deficiency of dietary iodine includes 12% school age children, whereas iodine is the major preventable cause of intellectual disabilities and development of central nervous system. A recent study based on the Global Burden of Disease Study 2019 (GBD 2019) shows that in thirteen nations, more than half of preschool-aged children had iodine deficiency and it is estimated that every year about 50 thousand still births occurs in Ethiopia just because of severe iodine deficiency among pregnant women.

Source: WHO/UNICEF/ICCIDD (2007). Assessment of iodine deficiency disorders and monitoring their elimination. Report of a joint WHO/UNICEF/ICCIDD consultation. Geneva: WHO