Vitamin D
Vitamin D is an essential fat-soluble vitamin. Good food sources of vitamin D include: certain fish such as: salmon, mackerels, and sardines.1 Vitamin D can also be found in fortified milk and breads as well as fruit juices.1
Solar Ultraviolent (UV) light stimulates the production of Vitamin D in the skin. It is estimated about 15 minutes of sun exposure around noon on a sunny day during Spring, Summer, and Autumn is sufficient for the daily Vitamin D requirement.2 However, using sunblock with SPF factor of 10 or higher will reduce Vitamin D production substantially.3
The 100% Daily Value for Vitamin D (based on a 2,000 kcal diet) is 400 IU* (=10 mcg), but it has been revised to 20 mcg as of May 27, 2016.13 The 100% Daily Value for pregnant or lactating women is 15 mcg, effective as of January 1st, 2020.13
*IU stands for International Unit; Vitamin D unit changed from IU to mcg by FDA. (effective January 1st, 2020)4,13
Forms
- Vitamin D3: Vitamin D3, also known as cholecalciferol, is a bioavailable form of vitamin D. Vitamin D3 can be derived from 7-dehydrocholesterol, extracted from the natural fat found in lamb’s wool. Vitamin D3 is the same type of vitamin D formed in human skin through exposure to natural sunlight.
Major Health Benefits
Vitamin D helps the absorption of calcium and phosphorous. Thus, Vitamin D is critical for proper formation and maintenance of healthy bones, teeth, and muscular function.5-7 Vitamin D also contributes to the normal function of the immune system and may help prevent the development of autoimmunity in some autoimmune disorders such as: type 1 diabetes, multiple sclerosis, and rheumatoid arthritis.8-11 Vitamin D also plays a role in increasing cell division (differentiation) leading to cancer prevention.5 Deficiency of Vitamin D can lead to rickets in children and infants, and muscle weakness and pain, excessive production of parathyroid hormone (PTH), and bone breakdown.9,12