Vitamin D Supplementation in Northern European Winters: Evidence, Dose and the Gap Between Guidance and Practice
DOI:
https://doi.org/10.5281/zenodo.22275642Keywords:
Vitamin D, 25-hydroxyvitamin D, Supplementation, Northern Europe, FortificationAbstract
Two authoritative reviews of vitamin D status in Northern Europe disagree by a wide margin. One reports that 43 to 92 per cent of
adults and 89 to 97 per cent of teenage girls have serum 25-hydroxyvitamin D below 50 nmol/L; another reports that deficiency at
the same threshold occurs in under 20 per cent of the population in Northern Europe, against 30 to 60 per cent in Western,
Southern and Eastern Europe. The discrepancy is not a simple error. Where fortification policy and a supplementation tradition
exist, latitude runs inversely to serum concentration, so the countries with least winter sunlight are not reliably the worst affected.
Dose guidance is similarly unsettled, ranging from a reference intake of 400 to 800 international units daily to expert consensus of
800 to 2,000, and up to 4,000 for defined groups. Across the European general population 13.0 per cent fall below 30 nmol/L and
40.4 per cent below 50.
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