“The two main ways to get vitamin D are by exposing your bare skin to sunlight and by taking vitamin D supplements. You can’t get the right amount of vitamin D your body needs from food.
The most natural way to get vitamin D is by exposing your bare skin to sunlight (ultraviolet B rays). This can happen very quickly, particularly in the summer. You don’t need to tan or burn your skin to get vitamin D. You only need to expose your skin for around half the time it takes for your skin to begin to burn. How much vitamin D is produced from sunlight depends on the time of day, where you live in the world and the color of your skin. The more skin you expose the more vitamin D is produced”