Question

The mineral which is required for the metabolism of Vitamin A

• A. Cobalt
• B. Zinc
• C. Iron
• D. Copper

Hint:

Mineral-Vitamin Synergisms:
Zinc $\leftrightarrow$ Vitamin A (RBP synthesis & Retinol Dehydrogenase).
Selenium $\leftrightarrow$ Vitamin E (Glutathione Peroxidase antioxidant synergy).
Cobalt $\leftrightarrow$ Vitamin $\text{B}_{12}$.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Nutritional trace element interactions: zinc is essential for hepatic synthesis of retinol-binding protein (RBP) and serves as the catalytic cofactor for retinol dehydrogenase.
Key Formula or Approach:
\[ \text{Retinol (Vitamin A)} \xrightleftharpoons{\text{Retinol Dehydrogenase [Zinc Metalloprotein]}} \text{Retinal (Rhodopsin Component)} \]

Step 2: Detailed Explanation:
In animal and fish biochemical nutrition:
- Zinc ($\text{Zn}^{2+}$) is obligately required for the metabolism, transport, and physiological action of Vitamin A (Retinol):
1. Retinol-Binding Protein (RBP) Synthesis: Zinc deficiency impairs hepatic synthesis of RBP, trapping vitamin A in liver storage and preventing mobilization to peripheral tissues.
2. Enzymatic Oxidation: Retinol Dehydrogenase (the metalloenzyme catalyzing the reversible interconversion of retinol to retinal in the visual cycle of the retina) is a zinc-dependent metalloprotein.
- Zinc deficiency thus precipitates secondary functional vitamin A deficiency (night blindness/abnormal vision).

Step 3: Final Answer:
Hence, the mineral required for Vitamin A metabolism is Zinc, corresponding to option (B).