This causes the skin to turn brown or tan. When the skin tans, this is evidence that the skin has been damaged by ultraviolet light. There is no such thing as a safe way to tan. Tanning is a process in which skin injury is occurring. The only benefit from exposing the skin to sunlight is for vitamin D production.
Most people obtain plenty of vitamin D from fortified milk.
If you take a multivitamin each day or eat a healthy diet, there is no reason to lie in the sun. One should never indulge in sunbathing. Sunbathing is a social disease like drinking alcohol or smoking cigarettes. Apply a sunscreen of SPF 15 or greater every day as a regular habit beginning at an early age. Each morning one should apply sunscreen to all skin that is exposed to sunlight.