Difficulty: Easy
Correct Answer: Provitamin A
Explanation:
Introduction / Context:
β-carotene is a carotenoid pigment widely distributed in plants and is nutritionally important for humans. Understanding its relationship to vitamin A clarifies labeling, fortification, and dietary recommendations.
Given Data / Assumptions:
Concept / Approach:
“Vitamin A” refers to retinol, retinal, and retinyl esters of animal origin or delivered forms. β-carotene is a plant-derived carotenoid that the body can enzymatically cleave to form retinal, which is then reduced to retinol or oxidized to retinoic acid. Hence, β-carotene is properly termed provitamin A.
Step-by-Step Solution:
Recognize chemical nature: β-carotene → carotenoid hydrocarbon.
Convertibility: intestinal dioxygenase splits β-carotene to retinal.
Terminology: compounds convertible to vitamin A are “provitamin A”.
Select “Provitamin A”.
Verification / Alternative check:
Nutrition references list retinol equivalents and consider β-carotene as a source of vitamin A after bioconversion, not vitamin A itself.
Why Other Options Are Wrong:
Vitamins C, D, K are unrelated. “Vitamin A” alone would imply preformed retinoids, not the precursor.
Common Pitfalls:
Equating dietary plant carotenoids directly with retinol; bioavailability and conversion efficiency vary.
Final Answer:
Provitamin A.
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