Sun exposure and 25-hydroxyvitamin D3levels in a community sample: Quantifying the association with electronic dosimeters.
There is uncertainty about the amount of sun exposure required to increase low blood 25-hydroxyvitamin D (25(OH)D3) levels, a possible disease risk factor. The study aimed to quantify the association between sun exposure and serum 25(OH)D3concentrations in a multiethnic community sample (n=502) living in Auckland (37°S) and Dunedin (46°S), New Zealand, aged 18-85 years. They wore electronic ultraviolet dosimeters between March and November (autumn, winter and spring) for 8 weeks to record their sun exposure. This was converted to standard erythemal doses (SEDs), corrected for clothing to generate equivalent full-body exposures, SEDEFB. Blood samples were collected at the end of weeks 4 and 8 to measure 25(OH)D3. Median weekly SEDEFBwas 0.33 during weeks 1-4 and 0.34 during weeks 5-8. Weekly exposures <0.5 SEDEFBduring weeks 5-8 were associated with decreasing 25(OH)D3concentrations at the end of week 8. There was a non-linear association between sun exposure and 25(OH)D3, with most of the increase in 25(OH)D3being at exposures <2 SEDEFBper week. This finding suggests that vitamin D status is increased by regular small sun exposures (<2 SEDEFBper week), and that greater exposures result in only small additional increases in 25(OH)D3.
Section of Epidemiology and Biostatistics, School of Population Health, University of Auckland, Auckland, New Zealand.
Robert K R
RKR
Scragg
Section of Epidemiology and Biostatistics, School of Population Health, University of Auckland, Auckland, New Zealand.
Alistair W
AW
Stewart
National Institute of Water and Atmospheric Research, Lauder, New Zealand.
Richard L
RL
McKenzie
Cancer Society Social and Behavioural Research Unit, Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand.
Anthony I
AI
Reeder
National Institute of Water and Atmospheric Research, Lauder, New Zealand.
J Ben
JB
Liley
Department of Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand.
Martin W
MW
Allen
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002112:Calcifediol / Q000097:blood*; D003020:Clothing; D004781:Environmental Exposure; D006801:Humans; D008875:Middle Aged; D009520:New Zealand; D000069079:Radiation Exposure; D012621:Seasons; D013472:Sunlight; D014466:Ultraviolet Rays; D055815:Young Adult
D002112:Calcifediol