Vitamin D, also known as “the sunshine vitamin”, is both a naturally-produced hormone and a vitamin (meaning that you can mitigate deficiencies by taking it orally). Cholecalciferol, or vitamin D3, is created by a reaction between UV rays and cholesterol in the skin of animals. Plants produce ergocalciferol (vitamin D2). Both vitamin D2 and vitamin D3 must be converted into the active form of vitamin D (1,25-dihydroxycholecalciferol, or calcitrol) before the body can use it.
Functions:
- Regulates levels of calcium and phosphorus in the blood, thus helping to maintain strong bones
- Plays a role in regulating cell growth, thus potentially helping to protect against some forms of cancer
- Reduces blood pressure by regulating the renin-angiotensin system and helping to keep arteries flexible
- May bolster the immune system and reduce the risk of autoimmune disorders and certain chronic diseases *more research regarding mechanisms is needed
Recommended Daily Amount (RDA): 600 IU for men and women ages 19 +, 800 IU for adults ages 70 +
Sources:
- Sun exposure (the length of time required varies dependent on skin color and the amount of skin exposed)
- Fortified foods (e.g. milk, soymilk, yogurt, orange juice, breakfast cereals)
- Fatty fish (e.g. salmon, sardines)
- Beef liver, egg yolks
- Supplements (check with your doctor first to determine need)
Vitamin D Fact Sheet