The vitamin synthesized when exposed to sunlight is vitamin D. When the skin is exposed to ultraviolet (UV) rays from sunlight, it initiates a chemical reaction that produces vitamin D, essential for maintaining healthy bones and teeth. Vitamin D also plays a crucial role in immune function and overall health. It can be obtained from certain foods, like fatty fish and fortified dairy, but sunlight exposure is a natural and efficient way for the body to produce this vital nutrient. Adequate vitamin D levels are important, especially in areas with limited sunlight during winter months, to prevent deficiencies and related health issues.