The skin's exposure to sunlight stimulates the production of which nutrient?

• A. Vitamin D
• B. Vitamin C
• C. Iron
• D. Calcium

Answer: (A)

Sunlight exposure triggers the skin to synthesize vitamin D. UVB rays convert a cholesterol in the skin into previtamin D3, which then becomes vitamin D3. This vitamin D is processed by the liver and kidneys into the active form that helps the body absorb calcium and phosphate for healthy bones. Vitamin C, iron, and calcium are not produced by sun exposure—Vitamin C comes from foods and acts as an antioxidant, while iron and calcium are minerals obtained from the diet (with calcium absorption aided by active vitamin D). Factors like how much sun you get, skin color, age, and sunscreen use influence how much vitamin D your skin can make.