Vitamin C is required for –
**Core Concept**
Vitamin C, also known as ascorbic acid, plays a crucial role in various bodily functions, including collagen synthesis, iron absorption, and antioxidant defenses. It acts as a cofactor for enzymes involved in these processes.
**Why the Correct Answer is Right**
Vitamin C is essential for the hydroxylation of proline and lysine residues in collagen, a protein that provides structural support to connective tissue. This process is mediated by the enzyme prolyl hydroxylase, which requires vitamin C as a cofactor. Vitamin C also participates in the regeneration of other antioxidants, such as vitamin E, and helps to maintain the integrity of the blood-brain barrier.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because vitamin C is not directly involved in the regulation of blood pressure.
**Option B:** Incorrect because while vitamin C may have some role in immune function, it is not the primary vitamin required for immune system function.
**Option C:** Incorrect because vitamin C is not directly involved in the metabolism of carbohydrates.
**Clinical Pearl / High-Yield Fact**
Vitamin C deficiency, known as scurvy, can lead to impaired collagen synthesis, causing symptoms such as bleeding gums, joint pain, and poor wound healing. This condition is often seen in individuals with inadequate dietary intake of vitamin C, particularly those with restrictive diets or gastrointestinal disorders.
**Correct Answer:** D. Collagen synthesis.