Improved Dietary Guidelines for Vitamin D: Application of Individual Participant Data (IPD)-Level Meta-Regression Analyses

• Published in: Nutrients Vol. 9; no. 5; p. 469
• Main Authors: Cashman, Kevin, Ritz, Christian, Kiely, Mairead
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 08.05.2017; MDPI
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; blood serum; Child; Child, Preschool; Diet; Dietary Guidelines; Dietary Reference Intakes; dose response; Female; Humans; Male; Middle Aged; Nutrition Policy - trends; Nutritional Status; randomized clinical trials; Randomized Controlled Trials as Topic; Regression Analysis; Risk Assessment; Seasons; Vitamin D; Vitamin D - administration & dosage; Vitamin D - analogs & derivatives; Vitamin D - blood; vitamin D deficiency; Vitamin D Deficiency - prevention & control; Vitamin deficiency; Young Adult; DRV; vitamin D recommendations; Individual Participant Data-level meta-regression analyses; RDA; EAR
• ISSN: 2072-6643; 2072-6643
• DOI: 10.3390/nu9050469

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.