Inter-relationship Between Vitamin D Requirements and Calcium Intake in Older Adults (VitD-Ca)

University College Cork (UCC)

Status: Completed

Conditions: Vitamin D Deficiency

Treatments: Dietary Supplement: Vitamin D3 (20 micrograms/day); Dietary Supplement: Placebo

Study type: Interventional

Funder types: Other

Identifiers

NCT01990872

PR-IC-1111-10005

Details and patient eligibility

About

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.

Full 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.

Enrollment: 125 patients

Sex: All

Ages: 50 to 80 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Prevention

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

---

125 participants in 4 patient groups, including a placebo group

Placebo in high calcium group

Placebo Comparator group

Description:

Placebo + habitual dietary calcium intake (\>1000 mg/d)

Treatment:

Dietary Supplement: Placebo

Vitamin D3 in low/moderate calcium group

Active Comparator group

Description:

Vitamin D3 (20 microgram/day) + habitual calcium intake \<700 mg/d

Treatment:

Dietary Supplement: Vitamin D3 (20 micrograms/day)

Placebo in low/moderate calcium group

Placebo Comparator group

Description:

Placebo + habitual calcium intake \<700 mg/d

Treatment:

Dietary Supplement: Placebo

Vitamin D3 in high calcium group

Active Comparator group

Description:

Vitamin D3 (20 microgram/day) + habitual calcium intake (\>1000 mg/d)

Treatment:

Dietary Supplement: Vitamin D3 (20 micrograms/day)