Sunlight is the richest source of which vitamin?

Appeared in: AIIMS Nagpur NO - 2018

Explanation

Sunlight is the primary natural source of Vitamin D.
Exposure to ultraviolet B (UVB) radiation from the sun triggers the synthesis of Vitamin D in the skin.
A precursor molecule in the skin, 7-dehydrocholesterol, is converted to Vitamin D3 (cholecalciferol) upon sun exposure.
This vitamin is essential for calcium absorption and bone health.

Option A: Vitamin B refers to a complex of several vitamins that are water-soluble and must be obtained from the diet. They are not synthesized through sun exposure.
Option C: Vitamin A is a fat-soluble vitamin obtained from dietary sources, either as preformed vitamin A (retinol) from animal products or as provitamin A (carotenoids) from plants.
Option D: Vitamin C (ascorbic acid) is a water-soluble vitamin that humans cannot synthesize and must obtain from food, particularly fruits and vegetables.

Visual 1: Diagram: The process of Vitamin D synthesis in the skin, showing UVB rays from the sun converting 7-dehydrocholesterol into Vitamin D3.
Visual 2: Infographic: A chart comparing the primary sources of Vitamins A, B, C, and D, highlighting sunlight for Vitamin D and various foods for the others.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Sources of Vitamins as background academic context rather than a clinical decision trigger.
Nurses play a crucial role in educating patients about safe sun exposure to maintain adequate Vitamin D levels, balancing the benefits against the risks of skin cancer.
Assessment for Vitamin D deficiency is important in high-risk groups, including the elderly, individuals with limited sun exposure, and people with darker skin pigmentation. Symptoms can include bone pain and muscle weakness.
What if? A patient has chronic kidney disease. Their ability to convert Vitamin D into its active form (calcitriol) is impaired. Therefore, even with adequate sun exposure, they would likely need supplementation with an active form of Vitamin D to prevent bone disease.

How to Approach the Question

This is a factual recall question that tests your knowledge of basic nutrition.
Identify the key components of the question: 'Sunlight' and 'richest source of which vitamin'.
Systematically review your knowledge of the major vitamins (A, B, C, D, E, K) and their primary sources.
Recall the unique mechanism of Vitamin D synthesis, which is initiated by sun exposure on the skin.
Compare this knowledge with the given options to identify the correct match.
Eliminate the other options by recalling their main dietary sources (e.g., Vitamin C from citrus, Vitamin A from carrots).

Concept Tested & Keywords

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Practise the full AIIMS Nagpur NO - 2018

Attempt every question from this paper in a timed mock, then review the full solution for each one.