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.
RCT Entities:
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.
Authors: Bibi Petersen; Hans C Wulf; Margarita Triguero-Mas; Peter A Philipsen; Elisabeth Thieden; Peter Olsen; Jakob Heydenreich; Payam Dadvand; Xavier Basagaña; Tove S Liljendahl; Graham I Harrison; Dan Segerbäck; Alois W Schmalwieser; Antony R Young; Mark J Nieuwenhuijsen Journal: J Invest Dermatol Date: 2014-05-20 Impact factor: 8.551
Authors: Robert K R Scragg; Alistair W Stewart; Richard L McKenzie; Anthony I Reeder; J Ben Liley; Martin W Allen Journal: J Expo Sci Environ Epidemiol Date: 2016-09-07 Impact factor: 5.563