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Rebecca Wike Malone; Cathy Kessenich
Posted: 08/25/2008; Journal for Nurse Practitioners. 2008;4(6):448-456. © 2008 Elsevier Science, Inc.
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Abstract and Introduction
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Vitamin D deficiency can occur in infancy, childhood, midlife, and aging. Research is emerging regarding vitamin D deficiency and its effect on neuromuscular function, cancer, cardiovascular disease, inflammatory illnesses, and bone mineralization. Recent evidence has shown that there is a need for increased vitamin D supplementation across the lifespan. Nurse practitioners must understand the effect of vitamin D deficiency on multiple body systems, assessment for deficiency, treatment, and prevention.

Introduction
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The role of vitamin D and calcium absorption in the eldery with osteoporosis has been well documented. However, as more evidence is developed, it is becoming clear that vitamin D deficiency is not only affecting the elderly population, it has negative effects across the lifespan. It is estimated that 1 billion people worldwide have vitamin D deficiency or insufficiency.[1] Review of research in medical, nursing, and nutritional literature reveals the need for vitamin D education, supplementation, and follow-up in all ages and treatment settings.

Deficiency
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Deficiency occurs when people do not have adequate exposure to UVB rays or adequate dietary intake. According to the National Institutes of Health (NIH), 10 to 15 minutes of direct sunlight at least twice a week to the face, arms, hands, or back is sufficient to maintain optimum serum Vitamin D levels.[6] The common application of sunscreen and decreased outdoor sun exposure can result in inadequate production of vitamin D in the skin. Sunscreen application reduces vitamin D synthesis—SPF 8 by 92.5% and SPF 15 by 99%.[1,7] While there are varying opinions on whether or not sunscreen can be a primary cause of deficiency, it has been shown that sunscreen will reduce the synthesis of the vitamin.[7,8,9] People with darker skin pigmentation have a reduction of synthesis by 99% because the UVB rays are being absorbed by melanin. There is a reduction of 7-dehydrocholesterol in the skin as aging occurs—only 25% of vitamin D3 is synthesized in a 70-year-old.[10] Therefore, people with darker skin, and elders, need to ingest more vitamin D in their diets.