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Requirements for Vitamin D across the life span
William B Grant1, Barbara J Boucher
1Sunlight, Nutrition, and Health Research Center (SUNARC), San Francisco, CA, USA. wbgrant@infionline.net
Biological Research for Nursing
|January 19, 2011
Summary
Adequate vitamin D levels are linked to lower risks of cancer, heart disease, and infections. Maintaining sufficient vitamin D (25-hydroxyvitamin D 30-60 ng/ml) is crucial for overall health and reducing mortality.
Area of Science:
- Nutritional Science
- Public Health
- Endocrinology
Background:
- Observational studies link adequate vitamin D to reduced risks of numerous diseases, including cancer, cardiovascular diseases (CVDs), autoimmune disorders, diabetes, neurological conditions, infections, and pregnancy complications.
- Vitamin D sufficiency is also associated with lower all-cause mortality rates.
- Classical roles in bone health (rickets, osteomalacia) are well-established.
Purpose of the Study:
- To review the multifaceted role of vitamin D in promoting health and preventing various diseases.
- To highlight the importance of maintaining adequate serum 25-hydroxyvitamin D concentrations.
Main Methods:
- Review of ecological, cross-sectional, observational studies, and randomized controlled trials (RCTs) involving vitamin D supplementation.
- Analysis of research on vitamin D's impact on diverse health outcomes and mortality.
- Examination of recommended vitamin D intake levels and serum concentrations.
Main Results:
- Adequate vitamin D provision is associated with reduced risk across a spectrum of non-skeletal conditions.
- Increased vitamin D intake (over 400 IU/day) and repletion correlate with decreased all-cause mortality.
- Serum 25-hydroxyvitamin D levels of 30-60 ng/ml, achieved through 1,000-4,000 IU/day intake or UVB exposure, are suggested for preventing hypovitaminosis D-related illnesses.
Conclusions:
- Vitamin D plays a critical role in systemic health beyond bone maintenance.
- Maintaining optimal vitamin D status through sensible sun exposure or supplementation is recommended for all ages.
- Dietary sources alone are insufficient for preventing most vitamin D-related health risks.
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01:23Role of Skin in Vitamin D Synthesis
The skin plays a crucial role in the synthesis of vitamin D, a vital nutrient for various physiological processes in the body. Vitamin D is unique because it can be synthesized in the skin through a series of chemical reactions triggered by exposure to ultraviolet B (UVB) radiation from sunlight.
The solar UV B rays (290-315 nm) are absorbed by the skin, and 7-dehydrocholesterol (provitamin D3) photolyzes it to previtamin D3, which undergoes a rapid transformation to vitamin D3(cholecalciferol).
The solar UV B rays (290-315 nm) are absorbed by the skin, and 7-dehydrocholesterol (provitamin D3) photolyzes it to previtamin D3, which undergoes a rapid transformation to vitamin D3(cholecalciferol).
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