The Prevalence of Vitamin D Deficiency and the Determinants of 25(OH)D Concentration in Older Irish Adults: Data From The Irish Longitudinal Study on Ageing (TILDA).
Level 4 - case-series / case-control
Cross-sectional observational study
PubMed 28958047 · doi:10.1093/gerona/glx168
What was done
Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured in 5,356 community-dwelling older adults (aged 50–98 years) from The Irish Longitudinal Study on Ageing (TILDA). Questionnaires assessed demographic, geographic, lifestyle, and socioeconomic variables. Seasonal prevalence of deficiency (defined as 25(OH)D < 30 nmol/L) was calculated, and linear regression was used to evaluate predictors of 25(OH)D concentration.
What was found
The prevalence of vitamin D deficiency (< 30 nmol/L) was 13.1% (95% CI: 12.1–14.2). Deficiency was more prevalent among nonsupplement users, in winter, in smokers, in obese adults, the physically inactive, those living alone, and those aged over 80 years. Significant predictors (p < .05) of 25(OH)D concentration were supplement use (coefficient: 27.2 nmol/L [95% CI: 15.3–39.2]), summer season (5.9 [95% CI: 2.7–9.1]), smoking (-8.9 [95% CI: -12.6– -5.2]), and obesity (-4.0 [95% CI: -6.3– -1.7]).
Why it matters
This study provides representative population-level prevalence data and identifies key modifiable determinants of vitamin D deficiency in community-dwelling older adults.
Limits
The cross-sectional analysis precludes establishing causality. Determinants were collected via self-reported questionnaires, introducing potential recall or reporting bias. The sample was restricted to community-dwelling Irish adults, so findings may not generalize to institutionalized older adults or populations at different latitudes.
Cited by
- supports The Irish Longitudinal Study on Ageing (TILDA) showed that vitamin D supplementation provided health benefits.