UVA decreased serum levels of vitamin D - RCT Oct 2012

Changes in serum 25-hydroxyvitamin D and cholecalciferol after one whole-body exposure in a commercial tanning bed: a randomized study.

Endocrine. 2012 Oct;42(2):430-5. Epub 2012 Mar 6.
Langdahl JH, Schierbeck LL, Bang UC, Jensen JE.
Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark.

We wanted to evaluate the cutaneous synthesis of 25OHD and cholecalciferol after one whole-body exposure to ultraviolet radiation type B (UVB) in a randomized setup. Healthy volunteers were randomized to one whole-body exposure in a commercial tanning bed with UVB emission (UVB/UVA ratio 1.8-2.0%) or an identical placebo tanning bed without UVB. The output in the 280-320 nm range was 450 µW/cm². Blood samples were analyzed for 25OHD and cholecalciferol at baseline and during 7 days after treatment.

We included 20 volunteers, 11 to UVB and 9 to placebo treatment. During the first 6 h, no significant differences in 25OHD between the groups were found. At the end of the study, we found a mean increase of 25OHD in the UVB group of 4.5 nmol/l (SD 7 nmol/l) compared to a decline of -1.2 nmol/l (SD 7 nmol/l) in the placebo group (p = 0.1). A linear mixed model yielded an increase of 25OHD in the UVB group of 1.0 nmol/l per 24 h (p < 0.01). For cholecalciferol, we found a near significant increase of 1 pmol/l per hour in the UVB group compared to the placebo group during the first 6 h (p = 0.052). One tanning bed session had significant, but modest impact on the level of 25OHD during 7 days after exposure to UVB.

PMID: 22391940

Details: yellow = no UVB

Notice: Frequently (but not always) getting just UVA DECREASED the vitamin D levels.
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Spectrum of one of the bulbs

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Comments by VitaminDWiki

  • UVA destroys Vitamin D in the body (many previous hints of this)
    • Window glass block most of UVA, but ALL of UVB - thus getting UV thru glass appears to decrease your levels of vitamin D
    • This may be one of the reasons that truckers live much shorter lives: UVA without UVB ==> lowering of vitamin D levels
  • UVA + UVB: net increase in blood levels of vitamin D
  • UVB only: larger net increase (a single hint that it might be 6x this has not been confirmed)
    • Some bulbs have just UVB
  • There is a way to block all but UVB:i.e. block UVA and visible and IR (Heat) - see below

See VitaminDWiki

uv window glass.jpg

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