Vitamin D works overtime as both a vitamin and a hormone. While you can get some Vitamin D through food, most is produced by the skin in a process that begins with exposure to sunlight, and that takes a little longer in darker skin tones. This hormone is involved in a variety of functions including bone health, reducing inflammation, and supporting a healthy immune response. It is also intimately involved with the skin, and it is believed to have some anti-aging properties, though prolonged exposure to sunlight can also have the opposite effect due to damage known as photoaging.