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The vitamin D status among Tibetans
Gelsor Norsang1, LiWei Ma, Arne Dahlback
1Geophysics Institute, Tibet University, Tibet, China.
Photochemistry and Photobiology
|June 11, 2009
Summary
Tibetan nomads show severe vitamin D deficiency despite high sun exposure. Dietary habits, not UVB, appear to influence vitamin D levels in other occupations.
Area of Science:
- Nutritional science
- Endocrinology
- Public health
Background:
- Vitamin D is crucial for human health, synthesized via UVB exposure or dietary intake.
- Tibet presents a unique environment with high UVB and traditionally low dietary vitamin D.
- Understanding vitamin D status in diverse Tibetan populations is essential for public health.
Purpose of the Study:
- To assess vitamin D status (serum 25(OH)D levels) in various Tibetan populations.
- To investigate the influence of UVB exposure and dietary habits on vitamin D levels.
- To identify risk factors for vitamin D deficiency in the Tibetan region.
Main Methods:
- Blood samples collected from 63 individuals across different ages, occupations, and locations.
- Measurement of local UVB doses.
- Analysis of serum 25-hydroxyvitamin D (25(OH)D) concentrations using radioimmunoassay.
Main Results:
- Nomads exhibited severe vitamin D deficiency (25(OH)D < 30 nM), possibly due to clothing and sun exposure habits.
- Students, teachers, and farmers showed higher vitamin D levels than nomads.
- A significant portion of non-nomadic participants had levels below 75 nM, indicating potential insufficiency.
Conclusions:
- Vitamin D status among Tibetan nomads is alarmingly low.
- Dietary habits appear to be a significant factor in vitamin D status, more so than high UVB exposure.
- While nomads face severe deficiency, other occupational groups in Tibet generally have more normal vitamin D levels.
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