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Less than 18 percent of Irish take vitamin D, and 76 percent have less than 30 ng – April 2013

Vitamin D status of Irish adults: findings from the National Adult Nutrition Survey.

Br J Nutr. 2013 Apr 14;109(7):1248-56. doi: 10.1017/S0007114512003212. Epub 2012 Aug 10.
Cashman KD, Muldowney S, McNulty B, Nugent A, FitzGerald AP, Kiely M, Walton J, Gibney MJ, Flynn A.
School of Food and Nutritional Sciences, University College Cork, Cork, Republic of Ireland.

Previous national nutrition surveys in Irish adults did not include blood samples; thus, representative serum 25-hydroxyvitamin D (25(OH)D) data are lacking. In the present study, we characterised serum 25(OH)D concentrations in Irish adults from the recent National Adult Nutrition Survey, and determined the impact of vitamin D supplement use and season on serum 25(OH)D concentrations. Of the total representative sample (n 1500, aged 18+ years), blood samples were available for 1132 adults. Serum 25(OH)D was measured via immunoassay. Vitamin D-containing supplement use was assessed by questionnaire and food diary. Concentrations of serum 25(OH)D were compared by season and in supplement users and non-users.

Year-round prevalence rates for serum 25(OH)D concentration < 30, < 40, < 50 and < 75 nmol/l were 6.7, 21.9, 40.1 and 75.6 %, respectively (11.1, 31.1, 55.0 and 84.0 % in winter, respectively). Supplement users had significantly higher serum 25(OH)D concentrations compared to non-users. However, 7.5 % of users had winter serum 25(OH)D < 30 nmol/l. Only 1.3 % had serum 25(OH)D concentrations >125 nmol/l. These first nationally representative serum 25(OH)D data for Irish adults show that while only 6.7 % had serum 25(OH)D < 30 nmol/l (vitamin D deficiency) throughout the year, 40.1 % had levels considered by the Institute of Medicine as being inadequate for bone health. These prevalence estimates were much higher during winter time. While vitamin D supplement use has benefits in terms of vitamin D status, at present rates of usage (17.5 % of Irish adults), it will have only very limited impact at a population level. Food-based strategies, including fortified foods, need to be explored.

PMID: 22883239 {PDF is behind a $45 paywall}

Suspect that this study used a different vitamin D tester than the others reported below.
A vitamin D deficiency for the Irish of 85% to 90% would seem to agree with the other European studies
Speculation: does the Irish red hair/light skin allow getting more vitamin D from the sun?

See also VitaminDWiki