Duration of Vitamin D Stores After Prolonged Vitamin D Substitution

This study has been completed.
Information provided by (Responsible Party):
University of Tromso
ClinicalTrials.gov Identifier:
First received: November 13, 2012
Last updated: September 18, 2015
Last verified: September 2015
Ingested or skin produced vitamin D is either hydroxylated in the liver to 25-hydroxyvitamin D (25(OH)D), metabolized and excreted in the urine, or stored in adipose and other tissues. The capacity for vitamin D storage in adipose tissue is not known, nor the importance of such storage which may potentially be of vital importance when intake or solar exposure is limited. In the present study we will include 76 subjects who have participated in an intervention study with vitamin D (20.000 IU per week) versus placebo for the prevention of type 2 diabetes, and who have completed the study after 5 years or who have been excluded because of diagnosed type 2 diabetes or for other reasons. If vitamin D is stored to any extent in the body the subjects given 20.000 IU vitamin D per week for 2-5 years will have a considerable amount of stored vitamin D and accordingly, a slow decline in serum 25(OH)D during the following year without vitamin D substitution, which will be measured in the present study. If our hypothesis is correct, that vitamin D can be stored in significant amounts when the supply is abundant; current advice on vitamin D supplementation mainly during winter should be changed to "year around" in order to build up sufficient stores for the months without sufficient sun light.


Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Prospective
Official Title: Duration of Vitamin D Stores After Prolonged Vitamin D Substitution

Resource links provided by NLM:

Further study details as provided by University of Tromso:

Primary Outcome Measures:
  • half-life of serum 25-hydroxyvitamin D [ Time Frame: up to 12 months ] [ Designated as safety issue: No ]

Biospecimen Retention:   Samples Without DNA
blood samples and fat biopsy

Enrollment: 78
Study Start Date: November 2012
Study Completion Date: August 2015
Primary Completion Date: May 2015 (Final data collection date for primary outcome measure)
subjects previously given placebo
subjects previously given vitamin D


Ages Eligible for Study:   25 Years to 85 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population
Subjects who have previously participated in a vitamin D study

Inclusion Criteria:

  • previously participated in a vitamin D study

Exclusion Criteria:

  • pregnancy
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Please refer to this study by its ClinicalTrials.gov identifier: NCT01729013

University of Tromsø
Tromsø, Norway, 9037
Sponsors and Collaborators
University of Tromso
Principal Investigator: rolf jorde, professor University of Tromso
  More Information

No publications provided

Responsible Party: University of Tromso
ClinicalTrials.gov Identifier: NCT01729013     History of Changes
Other Study ID Numbers: Tromsø-Endo-2012-2 
Study First Received: November 13, 2012
Last Updated: September 18, 2015
Health Authority: Norway:National Committee for Medical and Health Research Ethics

Keywords provided by University of Tromso:
vitamin D

Additional relevant MeSH terms:
Vitamin D
Bone Density Conservation Agents
Growth Substances
Pharmacologic Actions
Physiological Effects of Drugs

ClinicalTrials.gov processed this record on February 10, 2016