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

Cashman, Kevin D.; Muldowney, Siobhan; McNulty, Breige A.; Nugent, Anne P.; Fitzgerald, Anthony P.; Kiely, Mairead E.; Walton, Janette; Gibney, Michael J.; Flynn, Albert

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

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Published Version

Date

2012-08-12

Authors

Cashman, Kevin D.

Muldowney, Siobhan

McNulty, Breige A.

Nugent, Anne P.

Fitzgerald, Anthony P.

Kiely, Mairead E.

Walton, Janette

Gibney, Michael J.

Flynn, Albert

Publisher

Cambridge University Press

Published Version

10.1017/S0007114512003212

Abstract

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.

Keywords

Vitamin D , Serum 25-hydroxyvitamin D , National nutrition surveys , Supplements

Citation

Cashman, K. D., Muldowney, S., McNulty, B., Nugent, A., FitzGerald, A. P., Kiely, M., Walton, J., Gibney, M. J. and Flynn, A. (2013) 'Vitamin D status of Irish adults: findings from the National Adult Nutrition Survey', British Journal of Nutrition, 109(7), pp. 1248-1256. doi:10.1017/S0007114512003212