Which vitamin is essential for calcium homeostasis and bone mineralization?

• A. Vitamin C
• B. Vitamin D (calciferol)
• C. Vitamin B12
• D. Vitamin K

Answer: (B)

Vitamin D regulates calcium and phosphate balance and bone mineralization. When activated to calcitriol, it increases the intestine’s absorption of calcium (and phosphate), supplying minerals needed for bone formation. It works with parathyroid hormone to keep blood calcium within a tight range, boosting gut absorption and, when needed, mobilizing calcium from bone to support critical functions. Without enough vitamin D, calcium absorption falls, bones don’t mineralize properly, and disorders like rickets or osteomalacia can develop. While other vitamins like C, B12, and K contribute to bone health in different ways, none regulate calcium homeostasis and mineralization as directly as vitamin D.