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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