Iodine

Sources of Iodine

Natural Sources

Iodine is naturally found in seawater and soil. Common dietary sources include seafood (fish, seaweed, shellfish), dairy products, and eggs.

Fortified Sources

Many countries fortify table salt with iodine (iodized salt) to ensure adequate intake.

Supplements

In cases of deficiency or dietary restrictions, iodine supplements may be used under medical guidance.

Functions of Iodine

Thyroid Hormone Synthesis: Iodine is crucial for the production of thyroid hormones, thyroxine (T4), and triiodothyronine (T3). These hormones regulate metabolism, growth, and development.

Neurodevelopment: Adequate iodine is particularly vital during pregnancy and infancy for the proper neurological development of the fetus and infant.

Effects of Iodine Deficiency

Goiter: Enlargement of the thyroid gland, known as goiter, is a common manifestation of iodine deficiency.

Hypothyroidism: Reduced thyroid hormone production leading to symptoms like fatigue, weight gain, and cold intolerance.

Developmental Delays: In severe cases, iodine deficiency can cause cretinism in infants, characterised by stunted physical and mental growth.

Pregnancy Complications: Deficiency during pregnancy can lead to miscarriage, stillbirth, and congenital anomalies.

Recommended Dietary Allowances (RDAs) for Iodine

The RDA for iodine varies with age, gender, and physiological status (e.g., pregnancy). Generally, adults require around 150 micrograms per day. Pregnant and lactating women need higher amounts.

Properties of Iodine

Chemical Nature

Iodine is a non-metallic element in the halogen group.

Stability

It is stable in food sources and not easily destroyed by cooking or processing.

Bioavailability

The bioavailability of iodine can vary depending on the source and dietary factors.

Factors Affecting Iodine Absorption

Dietary Goitrogens: Certain foods (like cruciferous vegetables) contain substances that can interfere with iodine utilisation.

Interaction with Other Minerals: Excessive intake of minerals like calcium and iron can compete with iodine absorption.

Health Conditions: Certain health conditions, such as autoimmune thyroid disease, can affect iodine absorption and utilisation.

Example Exam Questions and Answers

1. What are the primary functions of iodine in the body?

Iodine's primary functions include the synthesis of thyroid hormones which regulate metabolism, growth, and development, and supporting fetal and infant neurodevelopment.

2. What can be the potential effects of iodine deficiency in pregnant women?

In pregnant women, iodine deficiency can lead to complications such as miscarriage, stillbirth, congenital anomalies, and impaired neurodevelopment in the child.

3. Describe the role of iodine in thyroid hormone production.

Iodine is a key component in the structure of thyroid hormones, thyroxine (T4), and triiodothyronine (T3). These hormones are essential for regulating metabolic processes in the body.