Vitamin B-12 deficiency leads to which conditions?

• A. Scurvy
• B. Rickets
• C. Pernicious anemia and nervous system disorders
• D. Osteoporosis

Answer: (C)

Vitamin B12 deficiency disrupts both blood formation and nerve function. B12 is essential for DNA synthesis in rapidly dividing cells, so insufficient B12 leads to megaloblastic anemia; when absorption is impaired—as in pernicious anemia, where autoimmunity reduces intrinsic factor—the anemia becomes evident and is often labeled pernicious. B12 is also crucial for maintaining the myelin sheath that surrounds nerves, so a lack of it causes demyelination and neurological symptoms such as numbness or tingling, difficulty walking, and cognitive changes. Seeing both pernicious anemia and nervous system disorders together is a hallmark of B12 deficiency. Other deficiencies explain different problems—scurvy (vitamin C deficiency) affects collagen and gums; rickets (vitamin D deficiency) affects bone mineralization; osteoporosis involves bone density loss but not B12-related nerve or red blood cell issues.