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| Titel |
The solar UV exposure time required for vitamin D3 synthesis in the human body estimated by numerical simulation and observation in Japan |
| VerfasserIn |
Hideaki Nakajima, Masaatsu Miyauchi, Chizuko Hirai |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075125
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| Zusammenfassung |
| After the discovery of Antarctic ozone hole, the negative effect of exposure of human
body to harmful solar ultraviolet (UV) radiation is widely known. However, there is
positive effect of exposure to UV radiation, i.e., vitamin D synthesis. Although
the importance of solar UV radiation for vitamin D3 synthesis in the human body
is well known, the solar exposure time required to prevent vitamin D deficiency
has not been well determined. This study attempted to identify the time of solar
exposure required for vitamin D3 synthesis in the body by season, time of day, and
geographic location (Sapporo, Tsukuba, and Naha, in Japan) using both numerical
simulations and observations. According to the numerical simulation for Tsukuba at noon
in July under a cloudless sky, 2.3 min of solar exposure are required to produce
5.5 μg vitamin D3 per 600 cm2 skin. This quantity of vitamin D represents the
recommended intake for an adult by the Ministry of Health, Labour and Welfare, and the
2010 Japanese Dietary Reference Intakes (DRIs). In contrast, it took 49.5 min to
produce the same amount of vitamin D3 at Sapporo in the northern part of Japan
in December, at noon under a cloudless sky. The necessary exposure time varied
considerably with the time of the day. For Tsukuba at noon in December, 14.5 min
were required, but at 09:00 68.7 min were required and at 15:00 175.8 min were
required for the same meteorological conditions. Naha receives high levels of UV
radiation allowing vitamin D3 synthesis almost throughout the year. According to our
results, we are further developing an index to quantify the necessary time of UV
radiation exposure to produce required amount of vitamin D3 from a UV radiation
data. |
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