There are two types of vitamin D. Ergocalciferol, or D2, is produced by plants, and cholecalciferol, or D3, is produced in the skin by ultraviolent-B rays. Michael Holick, Ph.D., from Boston University's Bone Health Care Clinic, explains that to get the recommended amount of vitamin D, healthy individuals can go outside on a sunny day with exposed skin for just 15 minutes. Some people need to get the vitamin from other sources due to skin problems.
Getting Vitamin D
Many different factors affect synthesis of vitamin D3 in the skin. In 2008, researchers from Boston University School of Medicine found that darker skin and aged skin limit production of the vitamin, as do other factors such as where you live and wearing protective clothing. To prevent a deficiency, people who fall into these categories can get proper amounts of D3 from UVB lamps or by taking 1,000 IU of vitamin D supplements.
Seniors
Low vitamin D levels are common in seniors. The elderly are at risk of a vitamin D3 deficiency because they have a reduced ability to synthesize cholecalciferol in the skin by UVB light, according to the Linus Pauling Institute. Older folks also tend to have limited movement and may go outside less, restricting UVB contact. This problem has long-reaching complications. A 2002 study published in the "American Journal of Clinical Nutrition" has linked cholecalciferol deficiency to reduction in muscle mass, low muscle strength, falls and fractures.
Skin Cancer
The most common form of cancer in the United States is skin cancer, according to the Centers for Disease Control and Prevention. The sun's rays are directly responsible for this potentially deadly disease, and the best way to prevent it is by wearing a sunscreen with an SPF 15. Sun lotion is capable of blocking 93 percent of the sun's rays, according to Holick, but it also blocks 99 percent of vitamin D3 synthesis. The Skin Cancer Foundation suggests noncarcinogenic alternatives to sun exposure such as vitamin D in foods like salmon or milk and cereal.
Skin Conditions
Vitamin D has also been linked to a variety of skin conditions. In a 2010 study published by the "Journal of the American Academy of Dermatology," researchers found that vitamin D deficiency was linked to vitiligo vulgaris, an irreversible autoimmune skin condition. People with psoriatic arthritis, a chronic skin disorder accompanied by inflammatory arthritis, tend to have low levels of vitamin D. Research is being done to determined if vitamin D supplementation can reverse these conditions or ease symptoms.
References
- MayoClinic: Vitamin D; July 2011
- "American Journal of Clinical Nutrition"; Vitamin D Deficiency, Muscle Function, and Falls in Elderly People; Hennie CJP Janssen, et. al.; April 2002
- Linus Pauling Institute: Vitamin D
- Skin Cancer Statistics; November 2010
- FamilyDoctor: Skin Cancer: Saving Your Skin from Sun Damage; July 2010
- Skin Cancer Foundation: Sunscreens Explained
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