Question

Which vitamin enhances the absorption of iron?

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

Hint:

Dietary iron is absorbed best in its reduced ferrous (Fe 2+ ) form. A reducing agent in the gut therefore improves how much iron the body can take in.

Answer 1

The Correct Option is C

Step 1: Iron absorption basics.
Dietary iron is absorbed mainly in the duodenum and upper jejunum. Non-heme iron (Fe³⁺) must be reduced to the ferrous form (Fe²⁺) before it can be absorbed by the enterocyte transporter DMT1 (divalent metal transporter 1). Anything that promotes this reduction improves iron absorption.

Step 2: How does Vitamin C help?
Vitamin C (ascorbic acid) is a powerful reducing agent. It reduces Fe³⁺ to Fe²⁺ in the acidic stomach environment, making it suitable for DMT1 absorption. Vitamin C also forms a soluble iron-ascorbate complex that prevents iron from precipitating at the higher pH of the duodenum, keeping it bioavailable.

Step 3: Evaluate the other vitamins.
Vitamin A (Option 1): Important for vision and immune function; does NOT directly enhance iron absorption. Vitamin D (Option 2): Primarily controls calcium and phosphate absorption, not iron. Vitamin K (Option 4): Required for synthesis of clotting factors; does NOT enhance iron absorption.

Step 4: Clinical application.
In clinical practice, patients taking iron supplements are often advised to take them with orange juice (rich in Vitamin C) to improve absorption. This is why iron and Vitamin C are sometimes combined in one tablet.

Step 5: Confirm the answer.
Vitamin C enhances iron absorption by reducing Fe³⁺ to Fe²⁺ and by forming soluble complexes. It is the correct answer.


Answer: Option (3) — Vitamin C