Improved dietary guidelines for vitamin D: application of individual participant data (IPD)-level meta-regression analyses

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Cashman, Kevin D.
Ritz, Christian
Kiely, Mairead E.
ODIN Collaborators
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Dietary Reference Values (DRVs) for vitamin D have a key role in the prevention of vitamin D deficiency. However, despite adopting similar risk assessment protocols, estimates from authoritative agencies over the last 6 years have been diverse. This may have arisen from diverse approaches to data analysis. Modelling strategies for pooling of individual subject data from cognate vitamin D randomized controlled trials (RCTs) are likely to provide the most appropriate DRV estimates. Thus, the objective of the present work was to undertake the first-ever individual participant data (IPD)-level meta-regression, which is increasingly recognized as best practice, from seven winter-based RCTs (with 882 participants ranging in age from 4 to 90 years) of the vitamin D intake–serum 25-hydroxyvitamin D (25(OH)D) dose-response. Our IPD-derived estimates of vitamin D intakes required to maintain 97.5% of 25(OH)D concentrations >25, 30, and 50 nmol/L across the population are 10, 13, and 26 µg/day, respectively. In contrast, standard meta-regression analyses with aggregate data (as used by several agencies in recent years) from the same RCTs estimated that a vitamin D intake requirement of 14 µg/day would maintain 97.5% of 25(OH)D >50 nmol/L. These first IPD-derived estimates offer improved dietary recommendations for vitamin D because the underpinning modeling captures the between-person variability in response of serum 25(OH)D to vitamin D intake.
Vitamin D recommendations , DRV , RDA , EAR , Individual participant data-level meta-regression analyses
Cashman, K., Ritz, C., Kiely, M. and ODIN Collaborators (2017) 'Improved dietary guidelines for Vitamin D: Application of individual participant data (IPD)-Level meta-regression analyses', Nutrients, 9(5), 469 (17pp). doi: 10.3390/nu9050469
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