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UV every two weeks maintains summer vitamin D level – RCT Oct 2011

A small suberythemal UVB dose every second week is sufficient to maintain summer vitamin D levels: a randomized controlled trial.

Br J Dermatol. 2011 Oct 20
Bogh MK bogh at dadlnet.dk , Schmedes AV, Philipsen PA, Thieden E, Wulf HC.
Department of Dermatology, Copenhagen University Hospital, Bispebjerg, Denmark. Department of Clinical Biochemistry, Lillebaelt Hospital, Vejle, Denmark.

Background:? It is known that ultraviolet-B (UVB) radiation increases serum vitamin D level (25-hydroxyvitamin D(3) OH)D. However, there is uncertainty about the relationship between the maintenance of vitamin D status and UVB. Objective:? To define the frequency of UVB exposure necessary for maintaining summer 25(OH)D levels during the winter.

Patients/Methods:? A total of 60 participants were included from October 2008 to February 2009 (16 weeks) and randomized for UVB exposure of 1 standard erythema dose (SED) to ?88% body area once a week (n = 15 completed), every second week (n = 14 completed) or every fourth week (n = 12 completed). The controls (n = 14 completed) had no intervention. Vitamin D was measured at baseline, every fourth week before exposure and 2 days after the last UVB exposure.

Results:? The 25(OH)D levels (mean) after UVB exposure once a week increased significantly (71.9 to 84.5 nmol/l) (P<0.0001) whereas UVB exposure every second week maintained 25(OH)D levels (P = 0.16). A significant decrease in mean 25(OH)D levels were found after UVB exposure once every fourth week (56.4 to 47.8 nmol/l) (P<0.0001) and for the control group (64.8 to 40.1 nmol/l) (P<0.0001). Further, the development in 25(OH)D levels during the 16-weeks study period and the increase in 25(OH)D after the last UVB exposure were negatively correlated with baseline 25(OH)D levels (P<0.0001).

Conclusion:? Exposure to a UVB dose of 1 SED every second week to ?88% body area is sufficient for maintaining summer 25(OH)D levels during the winter.
Copyright © 2011 British Association of Dermatologists. PMID: 22013924

PDF is attached at bottom of this page

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Start with 29 ng/ml

UV over 88% of body area (assume front and back)
UV weekly ==> 34 ng
UV every 2 weeks ==> maintained
UV every 4 week ==> 19 ng
No UV (control) 26 ng ==> 16 ng

Standard erythema dose (SED level = The amount of UV which causes skin reddening ( not burning)
Actual UV amount not stated in abstract. Will vary with skin darkness

We guess for a white skinned person that less than SED is 5-20 minutes when surrounded by long UV powerful tubes, such as those used in tanning salons.

Very approximate costs to maintain vitamin D level for 6 months of winter are

  1. Take a vitamin D pill (say 50,000 IU) weekly: $6
  2. Go to a tanning salon very two weeks for 6 months - $150
    Be sure the salon has "low pressure" bulbs. The "high pressure" bulbs to not have enough UVB
  3. Buy a facial tanning unit Amazon for about $200 which amortizes over 10 years to $20
    Note these small units have far less intense UV - so might require 10X-30X longer time
  4. Buy a UV tanning bed for $1,000 (Google Shopping and amortize your cost over 10 years: $100
    Note: Cost of bed can be amortized over many people - cost of other solutions are per person.
    Can also consider lowering your cost by buying only enough (low pressure) bulbs to tan 1 side of body at a time.
  5. Take two vacations to a sunny climate: $7,000
    Vitamin D from a single vacation will last 2-3 months

See also VitaminDWiki

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Previous publications by the same lead author include

Br J Dermatol. 2011 Jan;164(1):163-9. doi: 10.1111/j.1365-2133.2010.10082.x.

Interdependence between body surface area and ultraviolet B dose in vitamin D production: a randomized controlled trial.

Bogh MK, Schmedes AV, Philipsen PA, Thieden E, Wulf HC.
Department of Dermatology, Copenhagen University Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark. bogh at dadlnet.dk

BACKGROUND: Ultraviolet (UV) B radiation increases serum vitamin D level expressed as 25-hydroxyvitamin-D(3) [25(OH)D], but the relationship to body surface area and UVB dose needs investigation.

OBJECTIVE: To investigate the importance of body surface area and UVB dose on vitamin D production after UVB exposure.

METHODS: We randomized 92 participants to have 6%, 12% or 24% of their skin exposed to 0·75 (7·5 mJ cm(-2) at 298 nm using the CIE erythema action spectrum), 1·5 (15 mJ cm(-2) ) or 3·0 (30 mJ cm(-2) ) standard erythema doses (SED) of UVB. Each participant underwent four UVB exposures at intervals of 2-3 days. Skin pigmentation and 25(OH)D levels were measured before and 48 h after the final exposure.

RESULTS:The increase in 25(OH)D after irradiation [?25(OH)D] was positively correlated with body surface area (P = 0·006; R(2) = 0·08) and UVB dose (P < 0·0001; R(2) = 0·28), and negatively correlated with baseline 25(OH)D (P < 0·0001; R(2) = 0·18), for the entire data sample. However, when analysing each body surface area separately, we found a significant UVB response correlation for 6% (P < 0·0001; R(2) = 0·48) and 12% (P = 0·0004; R(2) = 0·35), but not for 24%. We also found a significant skin area response correlation for 0·75 SED (P < 0·0001; R(2) = 0·56), but not for 1·5 and 3·0 SED when analysing each UVB dose separately. The relationships did not change significantly after adjustment of ?25(OH)D for baseline 25(OH)D.

CONCLUSION: The increase in 25(OH)D depends mainly on the UVB dose; however, for small UVB doses the area of irradiated body surface is important.

© 2011 The Authors. BJD © 2011 British Association of Dermatologists 2011. PMID: 21039402

Exp Dermatol. 2011 Jan;20(1):14-8. doi: 10.1111/j.1600-0625.2010.01201.x.

Vitamin D production depends on ultraviolet-B dose but not on dose rate: a randomized controlled trial.

Bogh MK, Schmedes AV, Philipsen PA, Thieden E, Wulf HC.
Department of Dermatology, Copenhagen University Hospital, Bispebjerg, Denmark. bogh at dadlnet.dk

Ultraviolet-B (UV-B) radiation increases serum vitamin D level expressed as 25-hydroxyvitamin D(3) (25(OH)D), but the dose-response relationship and the importance of dose rate is unclear. Of 172 fair-skinned persons screened for 25(OH)D, 55 with insufficient baseline 25(OH)D?50 nm (mean 31.2 nm) were selected and randomized to one of 11 groups of five participants. Each group was exposed to one of four different UV-B doses: 0.375, 0.75, 1.5 or 3.0 standard erythema dose (SED) for 1, 5, 10 or 20 min. All participants had four UV-B sessions with 2- to 3-day interval with 24% of their skin exposed. Skin pigmentation and 25(OH)D were measured before and after the irradiations. The increase in 25(OH)D after UV-B exposure (adjusted for baseline 25(OH)D) was positively correlated with the UV-B dose (P=0.001; R(2) =0.176) but not to dose rate (1-20 min). 25(OH)D increased in response to four UV-B treatments of 3 SED with 24.8 nm on average and 14.2 nm after four UV-B treatments of just 0.375 SED. In conclusion, the increase in 25(OH)D after UV-B exposure depends on the dose but not on the dose rate (1-20 min). Further, a significant increase in 25(OH)D was achieved with a very low UV-B dose.
© 2010 John Wiley & Sons A/S. PMID: 21158934

J Invest Dermatol. 2010 Feb;130(2):546-53. Epub 2009 Oct 8.

Vitamin D production after UVB exposure depends on baseline vitamin D and total cholesterol but not on skin pigmentation.

Bogh MK, Schmedes AV, Philipsen PA, Thieden E, Wulf HC.
Department of Dermatology, Copenhagen University Hospital, Bispebjerg, Copenhagen NV Vejle, Denmark. bogh at dadlnet.dk

UVB radiation increases serum vitamin D level expressed as 25-hydroxyvitamin-D(3) (25(OH)D), but the influence of skin pigmentation, baseline 25(OH)D level, and total cholesterol has not been well characterized. To determine the importance of skin pigmentation, baseline 25(OH)D level, and total cholesterol on 25(OH)D production after UVB exposure, 182 persons were screened for 25(OH)D level. A total of 50 participants with a wide range in baseline 25(OH)D levels were selected to define the importance of baseline 25(OH)D level. Of these, 28 non-sun worshippers with limited past sun exposure were used to investigate the influence of skin pigmentation and baseline total cholesterol. The participants had 24% of their skin exposed to UVB (3 standard erythema doses) four times every second or third day. Skin pigmentation and 25(OH)D levels were measured before and after the irradiations. Total cholesterol was measured at baseline. The increase in 25(OH)D level after UVB exposure was negatively correlated with baseline 25(OH)D level (P<0.001) and positively correlated with baseline total cholesterol level (P=0.005), but no significant correlations were found with constitutive or facultative skin pigmentation.
In addition, we paired a dark-skinned group with a fair-skinned group according to baseline 25(OH)D levels and found no differences in 25(OH)D increase after identical UVB exposure.

Attached files

ID Name Comment Uploaded Size Downloads
1067 Ultraviolet B Dose during winter months.pdf PDF admin 06 Feb, 2012 20:19 169.61 Kb 489
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