Iodine deficient population in the world is:
**Core Concept**
Iodine deficiency is a significant public health concern worldwide, affecting thyroid function and overall health. Iodine is essential for the synthesis of thyroid hormones, and its deficiency can lead to hypothyroidism, goiter, and cretinism. The iodine deficiency disorders (IDD) are a major cause of preventable intellectual disability and growth retardation.
**Why the Correct Answer is Right**
The correct answer is based on the fact that iodine deficiency is a widespread problem, particularly in regions where iodized salt is not used or where soil iodine levels are low. The prevalence of IDD varies by region, but it is most common in mountainous areas where the soil is poor in iodine. The World Health Organization (WHO) estimates that over 2 billion people worldwide are at risk of iodine deficiency, with the highest prevalence in South Asia, East Asia, and the Pacific.
**Why Each Wrong Option is Incorrect**
**Option A:** The Middle East and North Africa have iodine deficiency issues, but they are not the most affected regions globally.
**Option B:** South America has some iodine-deficient areas, but it is not the most affected continent.
**Option C:** Southeast Asia has iodine deficiency issues, but it is not the most affected region.
**Clinical Pearl / High-Yield Fact**
The most effective way to prevent iodine deficiency is through the universal use of iodized salt, which has been shown to significantly reduce the prevalence of IDD.
**Correct Answer:** D.