Osteomalacia is characterized by poorly mineralized bones due to deficiency of which nutrient?

• A. Vitamin D
• B. Calcium
• C. Phosphorus
• D. Vitamin C

Answer: (A)

Osteomalacia happens when the bone matrix (osteoid) is laid down but not properly mineralized. The mineralization process requires vitamin D to promote absorption of calcium and phosphate from the gut, maintaining adequate levels for bone mineralization. When vitamin D is deficient, calcium and phosphate absorption drop, osteoid remains poorly mineralized, and bones become soft and weak. That’s why vitamin D deficiency is the classic cause of osteomalacia.

Calcium deficiency can contribute to problems, but it’s the lack of vitamin D which directly impairs the mineralization process. Vitamin C deficiency affects collagen formation, not mineralization, and phosphorus deficiency can also disrupt mineralization but is not the typical defining cause in most cases.