Get acquainted with your nutrients - Iodine

Iodine is an essential micronutrient required at all stages of life, starting from the fetal stage. The amount of iodine present in an adult human body is very little, 15-20 mg. Most of it is concentrated in the thyroid gland which is about 70-80% of the total iodine in the body.

Iodide is more stable in nature after it acquires an extra electron and becomes negatively

charged (I^–). Iodide is a component of the thyroid hormone which is mainly involved in energy metabolism. Thyroid hormones play an important role in the regulation of several enzymes and metabolic processes.

The human body is dependent on iodine to produce thyroid hormones. Iodine deficiency is very critical in pregnancy because it may lead to neurological damage during fetal development. It is also very important during lactation.

Functions of iodine

The major function of iodine is the role it plays in the synthesis of thyroid hormones. Iodine is an important constituent of the thyroid hormones, which are made in the thyroid gland located in the neck. Thyroid hormone is synthesized using iodide and tyrosine amino acid.

There are two forms of thyroid hormones thyroxine (T4) and triiodothyronine (T3). They are so-called based on the number of iodide atoms they contain that 3 or 4. In thyroxine, 65 % of the weight is contributed by iodine and 59 % of the weight of T3 is iodine. These hormones regulate many vital biochemical reactions in protein synthesis and enzymatic activity.

Thyroid hormones help in brain development in the fetus during pregnancy and during infancy.

Recommended daily allowances

The Recommended Dietary Allowance (RDA) for adult men and women is 150 μg/day. During pregnancy and lactation, the requirement goes up to 200 micrograms/day.  About 120 micrograms of iodide is required by the thyroid gland to synthesize thyroid hormones.

Sources of iodine

Diet is the main source of iodine and iodine content is dependent upon the iodine content of water and soil. The coastal region soils are rich in iodine compared to the soils inland. Vegetables grown in iodine-rich soil are good sources of iodine. Drinking water also contains iodine. Seaweeds such as wakame, nori or mekabu, used in some Asian cuisines for making soups, salads, and condiments, are rich sources of iodine.

Bioavailability of iodine

Healthy and normal adults can absorb 90% of dietary iodine. When thyroxine is taken orally the bioavailability is about 75 percent.

Iodine deficiency

Iodine deficiency leads to insufficient secretion of thyroid hormones by the thyroid gland. The thyroid gland enlargement or goiter as it is called is the symptom of iodine deficiency. The size of the thyroid gland increases in because of iodine deficiency. Iodine deficiency during childhood has an adverse effect on growth, organ development, and brain development.

To combat iodine deficiency, increase dietary iodine intake. One of the steps taken by authorities is introducing iodized salt. Reduce goitrogen containing foods. Goitrogens are substances that interfere with thyroid hormone production or utilization. In areas where iodine deficiency was eliminated the infant mortality rates also decreased.