Inter-relationship Between Vitamin D Requirements and Calcium Intake in Older Adults

N/ACompletedNCT01990872

University College Cork125 enrolled

Overview

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.

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

DOUBLE

Enrollment

125

Conditions

Vitamin D Deficiency

Interventions

Vitamin D3 (20 micrograms/day)DIETARY_SUPPLEMENT

Vitamin D3 (20 micrograms/day)

PlaceboDIETARY_SUPPLEMENT

Placebo (0 micrograms vitamin D3/day)

Eligibility

Sex: ALLMin age: 50 YearsMax age: 80 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Locations (1)

Human Dietary Studies Facility, School of Food and Nutritional Sciences, University College Cork, Cork, Ireland

Cork, Ireland

Outcomes

Primary Outcomes

Response of serum 25(OH)D concentration over winter in subjects stratified by calcium intake

Time frame: 0, 8, 15 weeks

Secondary Outcomes

Serum albumin-adjusted calcium

Time frame: 0, 8, 15 weeks

serum parathyroid hormone

Time frame: 0, 8, 15 weeks

Serum 24,25(OH)2D

Time frame: 0 and 15 weeks

Serum 1,25(OH)2D

Time frame: 0 and 15 weeks

Serum free 25(OH)D

Time frame: 0 and 15 weeks

Serum vitamin D binding protein

Time frame: 0 and 15 weeks

Data from ClinicalTrials.gov

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