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Vitamin D winter lasts from 4 to 215 days in Europe – Dec 2022

Comprehensive Analysis of Seasonal and Geographical Variation in UVB Radiation Relevant for Vitamin D Production in Europe

Nutrients 2022, 14(23), 5189; https://doi.org/10.3390/nu14235189
Tarinee Khanna 1,†, Rasha Shraim 1,2,† , Masa Zarkovic 1,3, Michiel van Weele 4 , Jos van Geffen 4 and Lina Zgag

Days lacking UVB to make Vitamin D (winter): 4 to 215 days in Europe


5X difference in peak UVB

Dermal synthesis, following sun exposure, is the main source of vitamin D. This study characterizes ambient UVB radiation relevant for vitamin D production in Europe. A biological weighing function was applied to data from the Tropospheric Emissions Monitoring Internet Service (TEMIS) for 46 capital cities over an 18-year period (2004–2021) to isolate wavelengths relevant for vitamin D production (D-UVB). Cumulative and weighted D-UVB (CW-D-UVB) were calculated to approximate seasonal vitamin D accumulation and diminution. Monthly 25(OH)D concentration measurements were extracted from published reports. All data were analyzed by location and time.
Despite a moderate latitudinal range (35–64° N), we observed large—up to five-fold—regional differences: the highest mean diurnal D-UVB dose of 5.57 kJ/m2 (SD = 3.55 kJ/m2) was observed in Nicosia (Cyprus) and the lowest in Reykjavik (Iceland, 1.16 ± 1.29 kJ/m2).
Seasonal differences in diurnal D-UVB dose were even more pronounced, with a median 36-fold difference between annual peak and trough depending on a location (range: 10- to 525-fold).
The mean duration of “vitamin D winter” was 126 days but varied widely (4 to 215 days).
Monthly CW-D-UVB and 25(OH)D changes were very strongly correlated: the changes in 25(OH)D concentration increased by 12.6 nmol/L for every 100 kJ/m2 increment of CW-D-UVB in population-based studies (r2 = 0.79, p-value = 1.16 × 10−37). Understanding the differences in D-UVB radiation can help understand determinants of vitamin D status and guide region- and season-specific safe and effective sunlight exposure recommendations and vitamin D supplementation guidelines.
 Download the PDF from VitaminDWiki

4 possible reasons for HIGHER Vitamin D in Northern latitudes

  1. Vitamin D fortification of food - especially Finland
  2. More fish consumption (provided not farmed fish)
    • Iceland: fish 91 kg /person annually/ Mainly cod and haddock - which are not farmed
  3. Paler skin
  4. Lactase persistence Jan 2020 FREE PDF
    • "" It was found that individuals with the genetic LP variant had considerably higher levels of serum 25(OH)D (P < 2 × 10−16"

2 possible reasons for LOWER vitamin D in Northern Latitudes

  1. Fewer hours of summer UVB
    might get UVB from 9 AM to 3 PM near the eqator, vs. 10 AM to 2 PM in mid-latitudes or 11 AM to 1 PM in high latitudes
  2. Less intense UVB

VitaminDwiki - UV and D contains

377 items in UV category   see also

VitaminDWiki - 5 studies in both categories UV and Europe

This list is automatically updated

UVB lamp appears to give 2,000 IU/ min. if young, 200 IU/min if senior (founder of VitaminDWiki)

Make your own UVB Vitamin D lamp for 40 dollars - Jan 2019
I turn around while in front of it for 3 minutes every day in the winter and have 10 seconds on my face ~ 600 IU
I found that staying still would cause a "sun" burn in <1 minute
I also take 100,000 IU of vitamin D once every 4 days during all seasons
Have eyes closed while the lamp is on - the UVB will damage the eyes

VitaminDwiki - Iceland and Vitamin D - many studies

Created by admin. Last Modification: Wednesday April 24, 2024 10:24:45 GMT-0000 by admin. (Version 20)

Attached files

ID Name Comment Uploaded Size Downloads
18941 Henry UVB bulb.jpg admin 06 Dec, 2022 11.10 Kb 389
18940 UVB Europe chart.jpg admin 06 Dec, 2022 74.15 Kb 344
18939 Days on Winter.jpg admin 06 Dec, 2022 96.55 Kb 356
18938 UVB Europe_CompressPdf.pdf admin 06 Dec, 2022 590.23 Kb 165