The vitamin primarily produced in the skin through sun exposure is vitamin D. When UV rays from sunlight hit the skin, they convert a cholesterol derivative into vitamin D3, which the body can then utilize. Adequate sun exposure is essential for maintaining optimal vitamin D levels, impacting calcium metabolism and overall health. However, factors such as geographical location, skin tone, and sun exposure duration can influence vitamin D synthesis. Supplementation may be necessary for those with limited sun exposure or higher needs.