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Tanning bed twice a month slightly increased vitamin D levels during the winter – RCT Nov 2015

Narrowband Ultraviolet B Exposures Maintain Vitamin D Levels During Winter: A Randomized Controlled Trial.

Acta Derm Venereol. 2015 Nov 3. doi: 10.2340/00015555-2269. [Epub ahead of print]
Karppinen T1, Ala-Houhala MJ, Ylianttila L, Kautiainen H, Viljakainen H, Reunala T, Snellman E.
1Department of Dermatology, Tampere University Hospital, PO Box 2000, FIN-33521 Tampere, Finland. toni.karppinen at epilaser.fi, karppinen.toni.t at student.uta.fi.

VitaminDWiki Summary

UVB just strong enough to make a slight reddening
On entire body (not just upper or lower)

VitaminD levels October April
UVB twice a month 32 ng36 ng
UVB - none 31 ng 26 ng


  • Commerical tanning beds typically have a lot of UVA in addition to UVB
  • UVA appears to decrease the effective production of Vitamin D by UVB
  • Treatments every 18-22 days (instead of 14) might have resulted in no change from Oct to April.
  • Guess: Each treatment takes 3-15 minutes
    much longer if use less intense sun or only illuminate one side
  • 3X-5X longer times for those who do not produce Vitamin D as efficiently
    elderly, those with darker skins, etc
  • 2X-5X longer times also needed for those who need much larger doses to get the same response
    Obese, poor liver, poor gut, smokers, people with diseases which consume Vitamin D - such as Multiple Sclerosis

See also VitaminDWiki

3 tanning sessions raised vitamin D levels about 4 nanograms for about 4 weeks – July 2016

Exposure to solar ultraviolet B radiation during the summer months is the main source of vitamin D (VD) for people living in northern latitudes. The aim of this study was to determine whether artificial narrowband ultraviolet B (NB-UVB) whole-body exposures could maintain VD levels in winter. The intervention group received 2 standard erythema doses (SEDs) of NB-UVB exposures every second week from October 2013 to April 2014. In October 2013 serum 25-hydroxyvitamin D concentrations were 78.3 nmol/l in the intervention group (n = 16) and 76.8 nmol/l in the control group (n = 18). By April 2014 the concentrations had increased by 11.7 nmol/l (p = 0.029) in the intervention group and decreased by 11.1 nmol/l (p = 0.022) in the control group. The baseline VD concentration showed a negative correlation (p = 0.012) with body mass index (BMI). In conclusion, a suberythemal NB-UVB dose of 2 SED every second week maintains and even increases serum VD concentrations during the winter. A high BMI seems to predispose subjects to low levels of VD.

PMID: 26524984