Adequacy of calcium and vitamin D nutritional status in a nationally representative sample of Irish teenagers aged 13–18 years

Context and purpose: In light of the key roles of vitamin D and calcium in adolescent bone health, there is a critical need for representative data on nutritional status for both micronutrients in teenagers. The present work used data from the recent representative National Teens’ Food Survey II (2019–2020) to assess calcium and vitamin D intakes of teenagers in Ireland, including adequacy of such intakes, as well as, for the first time, to characterise serum 25-hydroxyvitamin D (25(OH)D) concentrations and their determinants. Methods: Usual calcium and vitamin D intake estimates were generated using food intake data (via 4-day weighed food records) from a nationally representative sample of teenagers aged 13–18 years in Ireland (n 428). Serum 25(OH)D was measured (via LC–MS/MS) in the 57.5% (n 246) who provided a blood sample. Results: Sixty-seven and 94% of Irish teenagers had intakes of calcium and vitamin D below the respective Estimated Average Requirements values, reflecting a high degree of inadequacy of intake for both micronutrients (and higher in girls than boys; P < 0.001). In addition, 21.7% and 33.1% of teenagers had serum 25(OH)D < 30 nmol/L (risk of vitamin D deficiency) and 30–49.9 nmol/L (inadequacy), respectively. Extended winter sampling, being aged 16–18 years, low total vitamin D intake, being overweight/obese or being of non-white skin type were significant (P < 0.05) predictors of serum 25(OH)D < 30 nmol/L. Conclusions: There was a high prevalence of inadequacy of intake of calcium and vitamin D in Irish teenagers, and a fifth were at increased risk of vitamin D deficiency.