Solar UV Doses of Young Americans and Vitamin D3 Production.

Environ Health Perspect. 2011 Aug 18.

Godar DE, Pope SJ, Grant WB, Holick MF.

Food and Drug Administration

Background: Sunlight contains UVB radiation (290-315 nm) that affects human health in both detrimental (skin cancers) and beneficial (vitamin D3) ways. Serum 25-hydroxyvitamin D concentrations of young Americans (?19 yr) show many have deficient (<50 nmol/L, 20 ng/ml) or insufficient (<75 nmol/L, 30 ng/ml) vitamin D levels, indicating they are not getting enough sun exposure.

Those findings are in conflict with some calculated, published values that suggest people make "ample" vitamin D3 (~1,000 IU/day) from their "casual," or everyday, outdoor exposures even if they diligently use sunscreens with sun protection factor 15.

Objective: We estimated how much vitamin D3 young Americans (~2,000) produce from their everyday outdoor UV doses in the north (45°N) and south (35°N) each season of the year with and without vacationing.

Methods: To do these vitamin D3 calculations properly, we used geometric conversion factors that change planar to whole body doses, which previous calculations did not incorporate.

Results: Our estimates suggest that American children may not be getting adequate outdoor UVB exposures to satisfy their vitamin D3 needs all year, except some Caucasians during the summer if they do not diligently wear sunscreens except during beach vacations.

Conclusion: These estimates suggest most American children may not be going outside enough to meet their minimal (~600 IU/day) or optimal (?1,200 IU/day) vitamin D requirements.

PMID: 21852226

Figure 3 - 1.6 hours hours outside each day

Much more than 10 minutes/day
Does not seem to indicate time of day nor amount of clothing

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See also VitaminDWiki

• Overview Deficiency of vitamin D
• All items UV and Vitamin D 382 items
• All items Noontime Sun and Vitamin D 333 items
• No – 10 minutes per day of sun-UVB is NOT enough