What are two types of vitamins that are synthesized naturally?

Two types of vitamins that are synthesized naturally in the body are vitamin D and vitamin K. Vitamin D is produced when the skin is exposed to sunlight, specifically ultraviolet B (UVB) rays. Vitamin K can be synthesized by gut bacteria, helping in blood clotting and bone health. Both vitamins play essential roles in various bodily functions and can also be obtained from dietary sources.