Plasma Vitamin D and 25OHD Responses of Young and Old Men to Supplementation with Vitamin D₃

Abstract

Objectives: This study was conducted to determine whether there are age differences in the plasma parent vitamin D and 25-hydroxyvitamin D (25OHD) responses to eight weeks of supplementation with 20 μg/day of vitamin D₃.

Methods: Twenty-five healthy young men (age 18–35) and 25 healthy older men (62–79) were randomly assigned to supplementation with 20 μg/day of vitamin D₃ or to no intervention and followed for eight weeks. Plasma vitamin D₃ was measured by high performance liquid chromatography and 25OHD was measured by competitive protein binding.

Results: Both young and old men in the supplemented group had pronounced, rapid and similar increases in plasma vitamin D₃, whereas vitamin D₃ concentrations were stable in the control group. By the end of the eight-week adaptation period, plasma vitamin D₃ of young and old men had increased by 4.3 and 6.2 nmol/L respectively. In the supplemented group, mean 25OHD concentrations of both the young and old men increased during the study, and the magnitude of the change after eight weeks was nearly identical in the two age groups (22.5 and 22.1 nmol/L in the young and the old men, respectively). In the control group there was a modest decrease in 25OHD of both the young and old men.

Conclusions: There appears to be no age-related impairment among men in the absorption or metabolism of 20 μg/day of vitamin D₃ taken orally for at least eight weeks.

• vitamin D
• cholecalciferol
• intestinal absorption
• 25-hydroxyvitamin D
• aging
• vitamin supplementation

The vitamin D tablets for this study were provided by the General Nutrition Corp. (Pittsburgh, PA). Funding for study measurements was provided under a grant from the USDA National Research Initiative Competitive Grants Program.

Notes

This material is based on work supported by the U.S. Department of Agriculture, under agreement No. 58-1950-9-001. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors, and do not necessarily reflect the view of the U.S. Department of Agriculture.

This paper was presented in part as a poster at the annual meeting of the American Society for Bone and Mineral Research, Phoenix, AZ, October 13, 2001.