Vitamin D intake and status in Ireland: a narrative review

Vitamin D is crucial for musculoskeletal health, with evidence suggesting non-skeletal benefits. Cutaneous vitamin D synthesis is limited in Ireland due to its northern latitude (52–55°N) and the population is dependent on dietary sources, yet intakes are inadequate. No study to-date has comprehensively examined vitamin D intakes and status in Ireland (Northern Ireland and the Republic). We aimed to review the evidence since 2010 and summarise the results in subgroups of the Irish population. We found that in the largest studies prevalence of deficiency [25-hydroxyvitamin D (25(OH)D) < 30 nM/l] was 15–17% in pregnancy, 15–23% in children and 13% in adults. Approximately half the population had 25(OH)D < 50 nM/l. There were only four small studies in an ethnic population with the largest in Southeast Asians finding that 67% were deficient. All studies found higher rates of deficiency and levels <50 nM/l in winter v. summer. Vitamin D intake was lowest in children (mean 2⋅3–4⋅2 μg/d) and pregnant women (mean 1⋅9–5⋅1 μg/d) and highest in older adults (6⋅9 μg/d), with over 90% of the population not meeting the recommended daily allowance. This review indicates that low vitamin D status and dietary vitamin D intake are widespread with children, adolescents, younger adults, pregnant women and ethnic minorities most at-risk. However, data are sparse in at-risk groups including the Travelling community, non-Europeans and institutionalised adults. Given the significant prevalence of deficiency, public health policies to promote better awareness of recommended vitamin D intakes and explore the options of food fortification are needed to address this issue.