25(OH)D2half-life is shorter than 25(OH)D3half-life and is influenced by DBP concentration and genotype

Abstract

Objective: The objective of the study was to compare the plasma half-lives of 25(OH)D2and 25(OH)D3in two distinct populations with different dietary calcium intake and 25(OH)D status. Participants: Healthy men (aged 24 and 39 y), resident in The Gambia (n = 18) or the United Kingdom (n = 18) participated in the study. Interventions: The intervention included an oral tracer dose of deuterated-25(OH)D2and deuterated-25(OH)D3(both 40 nmol). Blood samples were collected over 33 days. Main Outcome Measures: 25(OH)D2and 25(OH)D3plasma half-lives, concentrations of 25(OH)D, and vitamin D binding protein (DBP) and DBP genotypes were measured. Results: 25(OH)D2half-life [mean (SD)] [13.9 (2.6) d] was shorter than 25(OH)D3half-life [15.1 (3.1) d; P=.001] for countries combined, and in Gambians [12.8 (2.3) d vs 14.7 (3.5) d; P