The primary vitamin synthesized through sun exposure is Vitamin D. When the skin is exposed to ultraviolet B (UVB) rays from sunlight, it triggers the production of this essential nutrient, which plays a crucial role in bone health, immune function, and calcium absorption. Adequate vitamin D levels are important for preventing deficiencies and associated health issues, such as osteoporosis. For individuals with limited sun exposure or other risk factors, supplementation may be necessary to maintain sufficient levels.