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. Issue 1 (1st January 2017)

• Record Type: Journal Article
• Authors: Karppinen, Toni; Ala-Houhala, Meri; Ylianttila, Lasse; Kautiainen, Hannu; Lakkala, Kaisa; Hannula, Henna-Reetta; Turunen, Esa; Viljakainen, Heli; Reunala, Timo; Snellman, Erna
• Is Part Of: International journal of circumpolar health. Volume 76:Issue 1(2017)
• Publication Date: 2017-01-01
• Subjects: 25(OH)D -- vitamin D -- ultraviolet -- UVB -- spring; Arctic medicine -- Periodicals; Circumpolar medicine -- Periodicals; Médecine arctique -- Périodiques; Médecine polaire -- Périodiques; Arctic medicine; Circumpolar medicine; Gezondheid; Noordpoolgebied; Cold Climate; Medicine; Antarctic Regions; Arctic Regions; Periodicals; 616.9881
• DOI: 10.1080/22423982.2016.1272790
• Languages: English
• ISSNs: 1239-9736

Abstract

ABSTRACT: 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.