Which of the following is a fat-soluble vitamin that helps in promotion of calcium absorption in the gut for bone health?

Question

Which of the following is a fat-soluble vitamin that helps in promotion of calcium absorption in the gut for bone health?

1. A. Vitamin D (Correct answer)
2. B. Vitamin A
3. C. Vitamin B
4. D. Vitamin C

Correct Answer

Option A — Vitamin D

Detailed Solution & Explanation

The correct answer is Vitamin D.

Key Points

• Vitamin D is fat-soluble and its central role is to promote absorption of calcium and phosphorus from the gut, without which dietary calcium passes through largely unused.
• The other options fail on one criterion or the other:
  • Vitamin A is fat-soluble but governs vision and epithelial health, not calcium uptake.
  • Vitamins B and C are water-soluble and have no such role.

Additional Information

• The four fat-soluble vitamins are A, D, E and K — stored in the liver and fatty tissue, so excess accumulates and can cause hypervitaminosis. Water-soluble vitamins (B-complex and C) are excreted in urine and need regular replacement.
• Vitamin D is unusual in being synthesised in the skin on exposure to ultraviolet-B sunlight, which is why it is often called the "sunshine vitamin" and why deficiency is common where sunlight exposure is limited.
• Deficiency causes rickets in children and osteomalacia in adults — both disorders of bone mineralisation, the direct consequence of failed calcium absorption.
• It functions more like a hormone than a classical vitamin, being converted in the liver and kidneys to its active form, calcitriol.