Clinical trial NCT01990872: Inter-relationship Between Vitamin D Requirements and Calcium Intake in Older Adults
Official title: Randomized Controlled Trial to Explore the Inter-relationship Between Vitamin D Requirements and Calcium Intake
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Vitamin D Deficiency
Keywords: Vitamin D status
25-hydroxyvitamin D
Vitamin D3
RCT
Calcium intake
Dietary requirement
Lead sponsor: University College Cork
Sponsor class: OTHER
First posted: 2013-11-25
Enrollment: 125
Sex: ALL
Minimum age (years): 50
Maximum age (years): 80
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: PREVENTION

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.

Eligibility criteria: 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

Primary outcomes:
measure: Response of serum 25(OH)D concentration over winter in subjects stratified by calcium intake
timeFrame: 0, 8, 15 weeks
Secondary outcomes:
measure: Serum albumin-adjusted calcium
timeFrame: 0, 8, 15 weeks
measure: serum parathyroid hormone
timeFrame: 0, 8, 15 weeks
measure: Serum 24,25(OH)2D
timeFrame: 0 and 15 weeks
measure: Serum 1,25(OH)2D
timeFrame: 0 and 15 weeks
measure: Serum free 25(OH)D
timeFrame: 0 and 15 weeks
measure: Serum vitamin D binding protein
timeFrame: 0 and 15 weeks
Other outcomes:
Locations:
city: Cork
country: Ireland
facility: Human Dietary Studies Facility, School of Food and Nutritional Sciences, University College Cork, Cork, Ireland
Study officials:
affiliation: University College Cork
name: Kevin D Cashman, BSc. PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Cashman KD, Kinsella M, Walton J, Flynn A, Hayes A, Lucey AJ, Seamans KM, Kiely M. The 3 epimer of 25-hydroxycholecalciferol is present in the circulation of the majority of adults in a nationally representative sample and has endogenous origins. J Nutr. 2014 Jul;144(7):1050-7. doi: 10.3945/jn.114.192419. Epub 2014 May 14.
citation: Cashman KD, Hayes A, O'Donovan SM, Zhang JY, Kinsella M, Galvin K, Kiely M, Seamans KM. Dietary calcium does not interact with vitamin D(3) in terms of determining the response and catabolism of serum 25-hydroxyvitamin D during winter in older adults. Am J Clin Nutr. 2014 Jun;99(6):1414-23. doi: 10.3945/ajcn.113.080358. Epub 2014 Apr 2.