Vitamin D Deficiency
Conditions
Keywords
Vitamin D status, 25-hydroxyvitamin D, Vitamin D3, RCT, Calcium intake, Dietary requirement
Brief summary
This winter-based placebo-controlled, single-dose vitamin D randomized controlled trial (RCT) aims to examine the impact of various levels of habitual calcium intake on dietary vitamin D requirements in older adults stratified by calcium intake. This will provide new data on the impact of different levels of calcium intake, ranging from low/moderate to high, on winter serum 25(OH)D levels, and their utilization and catabolism in adults.
Detailed description
The aim of this study is to perform a randomised controlled vitamin D3 intervention study in apparently healthy, free-living adults (aged 50+ y) to investigate whether different levels of habitual calcium intake, ranging from low-moderate to high, influence serum 25(OH)D concentrations and indices of vitamin D activation and catabolism during winter, when vitamin D intake is adequate versus inadequate. This research will provide new data and scientific understanding in relation to the impact of different levels of dietary calcium intake on vitamin D requirements in the older adult population. As such, this new data will inform dietary reference values for vitamin D.
Interventions
DIETARY_SUPPLEMENTVitamin D3 (20 micrograms/day)
Vitamin D3 (20 micrograms/day)
DIETARY_SUPPLEMENTPlacebo
Placebo (0 micrograms vitamin D3/day)
Sponsors
University College Cork
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
50 Years to 80 Years
Healthy volunteers
Yes
Inclusion criteria
Consenting white men and women aged ≥ 50 y
Exclusion criteria
* Unwilling to discontinue consumption of vitamin D-containing supplements 4 wks before the initiation of the study and throughout the study. * Planning to take a winter vacation (during the course of the 15-wk intervention) to a location at which either the altitude or the latitude was predicted to result in significant cutaneous vitamin D synthesis from solar radiation (e.g., a winter sun coastal resort or a mountain ski resort) * Use of tanning facilities of any type. * Pregnancy or planning to become pregnant during the study * A severe medical illness, * hypercalcaemia, * Known intestinal malabsorption syndrome, * Excessive alcohol use, * Taking medications known to interfere with vitamin D metabolism
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Response of serum 25(OH)D concentration over winter in subjects stratified by calcium intake | 0, 8, 15 weeks |
Secondary
| Measure | Time frame |
|---|---|
| Serum albumin-adjusted calcium | 0, 8, 15 weeks |
| serum parathyroid hormone | 0, 8, 15 weeks |
| Serum 24,25(OH)2D | 0 and 15 weeks |
| Serum 1,25(OH)2D | 0 and 15 weeks |
| Serum free 25(OH)D | 0 and 15 weeks |
| Serum vitamin D binding protein | 0 and 15 weeks |
Countries
Ireland
Outcome results
None listed