Seasonal Changes in Vitamin D-Effective UVB Availability in Europe and Associations with Population Serum 25-Hydroxyvitamin D.
Level 4 - case-series / case-control
Ecological comparative study combining atmospheric modeling with population survey data
PubMed 27589793 · doi:10.3390/nu8090533
What was done
Researchers modeled vitamin D-effective ultraviolet B (UVB) availability (J/m²) across nine European locations (latitudes 35° N to 69° N) using a validated UV irradiance model. They compared modeled UVB data to representative, standardized population serum 25-hydroxyvitamin D (25(OH)D) data from Ireland (51°–54° N), Iceland (64° N), and Norway (69° N) obtained from the European Commission-funded ODIN project.
What was found
UVB availability decreased with increasing latitude, and all locations exhibited significant seasonal variation. The duration of "vitamin D winter" ranged from zero months (at 35° N) to eight months (at 69° N). Large seasonal fluctuations in serum 25(OH)D observed in Irish adults were dampened in Norwegian and Icelandic adults despite lower UVB availability at higher latitudes, which co-occurred with higher vitamin D intakes. No specific numerical values for serum 25(OH)D or dietary intakes were reported in the abstract.
Why it matters
This study demonstrates that higher dietary vitamin D intake can mitigate the impact of prolonged seasonal lack of UVB radiation on population vitamin D status.
Limits
The abstract does not report participant sample sizes, demographic characteristics, or numerical serum concentrations and dietary intake levels. The ecological design compares modeled ambient irradiance with population datasets, precluding assessment of individual-level sun exposure behaviors, clothing habits, or supplement adherence.
Cited by
- supports Living above the 35th parallel prevents sufficient atmospheric penetration of UVB radiation to synthesize adequate vitamin D in the skin during winter months.