Which vitamin do humans receive primarily from the sun?

Humans primarily receive Vitamin D through exposure to sunlight. When UV rays from the sun come into contact with the skin, they trigger a chemical reaction that converts a precursor molecule into vitamin D3, which is then metabolized in the liver and kidneys to form active vitamin D. This vitamin plays a crucial role in bone health by regulating calcium and phosphorus levels in the body, which are essential for maintaining strong bones and overall health.

In contrast, the other vitamins listed are obtained primarily through dietary sources rather than sunlight. Vitamin B12 is mainly found in animal products such as meat, eggs, and dairy. Vitamin A is derived from animal-based foods and certain plant sources, like carrots and sweet potatoes, where it exists in the form of beta-carotene. Vitamin C is found predominantly in fruits and vegetables, such as oranges, strawberries, and leafy greens. Therefore, sunlight is uniquely significant in the synthesis of Vitamin D, making it essential for maintaining adequate levels in the body.