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

Type:Uv phototherapy   Time:2017-06-13 11:36:09
A small suberythemal ultraviolet B dose every second week is sufficient to maintain summer vitamin D levels: a randomized 

controlled trial.
Bogh MK1, Schmedes AV, Philipsen PA, Thieden E, Wulf HC.
Author information
Abstract
BACKGROUND:
It is known that ultraviolet (UV) B radiation increases serum 25-hydroxyvitamin D(3) [25(OH)D] level. However, there is 

uncertainty about the relationship between the maintenance of vitamin D status and UVB.
OBJECTIVES:
To define the frequency of UVB exposure necessary for maintaining summer 25(OH)D levels during the winter.
METHODS:
In total, 60 participants were included from October 2008 to February 2009 (16weeks) 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 2days after the last UVB exposure.
RESULTS:
The 25(OH)D levels (mean) after UVB exposure once a week increased significantly (from 71��9 to 84��5nmolL(-1) ) (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 

(from 56��4 to 47��8nmolL(-1) ) (P<0��0001) was found after UVB exposure once every fourth week and for the control group 

(from 64��8 to 40��1nmolL(-1) ) (P<0��0001). The development in 25(OH)D levels during the 16-week study period were 

negatively correlated with baseline 25(OH)D (P<0��0001). Further, the increase in 25(OH)D after the last UVB exposure was 

negatively correlated with the 25(OH)D level just before the last UVB exposure (P<0��0001).
CONCLUSIONS:
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.
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