Osteomalacia is most closely associated with deficiency of which nutrient?

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

Answer: (B)

Osteomalacia is caused by defective mineralization of bone matrix in adults, most commonly due to insufficient vitamin D. Vitamin D is essential for absorbing calcium and phosphate from the gut and delivering these minerals to the bone for proper mineralization. When vitamin D is deficient, calcium and phosphate availability for bone mineralization drops, leading to softer, fragile bones despite having the bone matrix in place. While calcium is involved in bone structure, without adequate vitamin D to enable mineral absorption, mineralization fails. Vitamin C and vitamin K influence other aspects of bone biology, but they do not cause the characteristic defective mineralization seen in osteomalacia.