The effect of vernal solar UV radiation on serum 25-hydroxyvitamin D concentration depends on the baseline level: observations from a high latitude in Finland

Humans obtain vitamin D from conversion of 7-dehydrocholesterol in the skin by ultraviolet B (UVB) radiation or from dietary sources. As the radiation level is insufficient in winter, vitamin D deficiency is common at higher latitudes. We assessed whether vernal solar UVB radiation at latitudes 61°N...

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Bibliographic Details
Published in:International Journal of Circumpolar Health
Main Authors: Toni Karppinen, Meri Ala-Houhala, Lasse Ylianttila, Hannu Kautiainen, Kaisa Lakkala, Henna-Reetta Hannula, Esa Turunen, Heli Viljakainen, Timo Reunala, Erna Snellman
Format: Article in Journal/Newspaper
Language:English
Published: Taylor & Francis Group 2017
Subjects:
25(OH)D
vitamin D
ultraviolet
UVB
spring
Arctic medicine. Tropical medicine
RC955-962
Arctic
Circumpolar Health
International Journal of Circumpolar Health
Online Access:https://doi.org/10.1080/22423982.2016.1272790
https://doaj.org/article/d9af046336e54e14b328446b93933816
Description
Summary:Humans obtain vitamin D from conversion of 7-dehydrocholesterol in the skin by ultraviolet B (UVB) radiation or from dietary sources. As the radiation level is insufficient in winter, vitamin D deficiency is common at higher latitudes. We assessed whether vernal solar UVB radiation at latitudes 61°N and 67°N in Finland has an impact on serum 25-hydroxyvitamin D [S-25(OH)D] concentrations. Twenty-seven healthy volunteers participated in outdoor activities in snow-covered terrain for 4–10 days in March or April, with their face and hands sun-exposed. The personal UVB doses and S-25(OH)D levels were monitored. A mean UVB dose of 11.8 standard erythema doses (SED) was received during an average of 12.3 outdoor hours. The mean S-25(OH)D concentration in subjects with a baseline concentration below 90.0 nmol/L (n=13) increased significantly, by 6.0 nmol/L from an initial mean of 62.4 nmol/L (p<0.001), whereas in those with a basal concentration above 90.0 nmol/L (n=12) it decreased significantly, by 6.7 nmol/L from a mean of 116.9 nmol/L (p<0.01). To conclude, only 7% of total body surface area was exposed to vernal sunlight and this was capable of increasing S-25(OH)D levels in subjects with a baseline level below 90 nmol/L but not in those with higher levels.

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