Vitamin D is a fat-soluble vitamin that is found in foods and also made in your skin. It has been shown that getting enough vitamin D can reduce your risk of developing osteoporosis or osteomalacia. This is because vitamin D is involved in promoting calcium absorption in the gut and in regulating calcium and phosphate concentrations in your blood.
Surprisingly, vitamin D is naturally found in very few foods. Most Americans get the majority of their vitamin D in foods that have had this nutrient added to them, such as in milk, orange juice, or cereal. Fish and fish oil are the best sources of naturally occurring vitamin D.
The human body can also make vitamin D using sunlight and a special form of cholesterol. You only need 15 minutes of sunlight on your hands a few times a week to make enough vitamin D for your whole body! It is very important to still wear sunscreen and stay out of the sun as much as possible because the UV radiation from the sun can cause cancer.
Vitamin D is also sold in supplemental form, often times paired with calcium. It is important to talk to your doctor before beginning any supplements, as there is a risk for adverse interactions with other medications you are taking or risk of toxicity.