Which of these vitamins is sourced both from sunlight and food?

BTSC Staff Nurse 1 August-2025

Applied Nutrition & Dietetics

Easy

Appeared in: BTSC Staff Nurse 1 August-2025

Explanation

Vitamin D is famously known as the 'sunshine vitamin' because it is endogenously synthesized in the skin upon exposure to ultraviolet B (UVB) rays from the sun.
The synthesis process involves the conversion of a precursor molecule, 7-dehydrocholesterol, present in the skin into cholecalciferol (Vitamin D3).
In addition to sun exposure, Vitamin D can be obtained exogenously from dietary sources.
Key food sources include fatty fish (like salmon, mackerel, and tuna), fish liver oils, egg yolks, and foods fortified with Vitamin D, such as milk, cereals, and orange juice.

Option B: The Vitamin B complex is a group of water-soluble vitamins that are not synthesized by the body through sun exposure. They must be obtained from the diet.
Option C: Vitamin C (ascorbic acid) is an essential nutrient that the human body cannot synthesize. It must be obtained entirely from dietary sources, primarily fruits and vegetables.
Option D: Vitamin A (retinol and carotenoids) is a fat-soluble vitamin obtained exclusively from the diet, either from animal sources or by converting carotenoids from plants. It is not produced by sun exposure.

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.
Understanding the dual sources of Vitamin D is crucial for nurses when advising patients on preventing deficiency, which can lead to rickets in children and osteomalacia in adults.
Nurses should assess patients for risk factors for Vitamin D deficiency, such as limited sun exposure (due to lifestyle, clothing, or geography), dark skin pigmentation, and certain medical conditions (e.g., malabsorption syndromes).
In India, despite ample sunlight, deficiency is prevalent due to factors like skin pigmentation, pollution, and cultural practices of covering the skin, making dietary intake and supplementation important.

How to Approach the Question

First, analyze the question to identify the key requirements: a vitamin sourced from BOTH 'sunlight' AND 'food'.
Recall the common names and primary sources of the vitamins listed in the options.
Consider Vitamin D, often called the 'sunshine vitamin'. This nickname is a strong clue that it's related to sun exposure.
Evaluate if Vitamin D also comes from food. Recall that it is found in fatty fish and fortified milk.
Briefly check the other options (Vitamin A, B, and C) to confirm they are primarily from food sources only.
Conclude that Vitamin D is the only option that uniquely fits both criteria, making it the correct answer.

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