Which of the following is the most common cause of megaloblastic anemia in India?

Explanation

## Epidemiology of Megaloblastic Anemia in India **Key Point:** In India, **dietary vitamin B12 deficiency in vegetarians** is the most common cause of megaloblastic anemia, whereas in Western countries, pernicious anemia (autoimmune) is more prevalent. ### Geographic and Dietary Variation | Cause | India | Western Countries | |-------|-------|-------------------| | **Dietary B12 deficiency** | Most common | Uncommon | | **Pernicious anemia** | Uncommon | Most common | | **Folate deficiency** | Common (second most) | Less common | | **Malabsorption** | Moderate | Common | **High-Yield:** India has a large vegetarian population, and B12 is found exclusively in animal products (meat, fish, eggs, dairy). Strict vegetarians and vegans are at high risk of dietary B12 deficiency. ### Why Pernicious Anemia Is Less Common in India - Pernicious anemia is an autoimmune condition (antibodies against intrinsic factor or gastric parietal cells) - More prevalent in Northern European populations and those of European descent - Relatively rare in Indian and Asian populations - Requires specific genetic and immunologic predisposition **Clinical Pearl:** Always ask about dietary habits in an Indian patient with megaloblastic anemia. A vegetarian or vegan diet is a major risk factor for B12 deficiency. ### Folate Deficiency in India - Second most common cause of megaloblastic anemia in India - Causes: poor dietary intake, malabsorption (celiac disease, tropical sprue), increased demand (pregnancy, hemolysis) - Tropical sprue (endemic in parts of India) is an important cause of folate malabsorption