A 38-year-old woman from rural Maharashtra presents with progressive weakness, paresthesias in the lower limbs, and a positive Romberg sign. She reports a predominantly rice-based diet with minimal meat intake. Blood investigations show macrocytic anemia. What is the most common cause of her vitamin B12 deficiency in the Indian population?

Explanation

## Most Common Cause of Vitamin B12 Deficiency in India **Key Point:** In the Indian population, dietary deficiency is the most common cause of vitamin B12 deficiency, particularly among vegetarians and those with low socioeconomic status consuming predominantly plant-based diets. ### Epidemiological Context Unlike Western countries where pernicious anemia (autoimmune) is common, India has a high prevalence of nutritional B12 deficiency due to: - Predominantly vegetarian diets in large population segments - Low intake of animal-derived foods (meat, fish, eggs, dairy) - Poverty and limited access to fortified foods - Cultural and religious dietary practices ### Clinical Presentation in This Case The patient's presentation is consistent with B12 deficiency: - Macrocytic anemia (elevated MCV) - Neurological manifestations: paresthesias, positive Romberg sign (posterior column involvement) - Dietary history: rice-based diet with minimal meat ### Comparison of B12 Deficiency Causes | Cause | Prevalence in India | Mechanism | Clinical Features | |-------|-------------------|-----------|------------------| | **Dietary deficiency** | **Most common** | Inadequate intake of animal products | Gradual onset, reversible with supplementation | | Pernicious anemia | Less common | Autoimmune destruction of gastric parietal cells | Insidious, requires lifelong B12 injections | | Gastrectomy | Rare | Loss of intrinsic factor-producing tissue | Post-surgical, predictable | | Crohn's disease | Uncommon | Malabsorption in terminal ileum | Associated GI symptoms | **High-Yield:** Dietary B12 deficiency is the leading cause in India and other developing nations with large vegetarian populations. It is preventable through dietary counseling and supplementation. **Clinical Pearl:** In Indian patients with B12 deficiency, always ask about dietary intake and vegetarian status before pursuing invasive investigations like endoscopy or antibody testing.