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Duration of Vitamin D Stores After Prolonged Vitamin D Substitution

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT01729013
First Posted: November 20, 2012
Last Update Posted: September 22, 2015
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Information provided by (Responsible Party):
University of Tromso
November 13, 2012
November 20, 2012
September 22, 2015
November 2012
May 2015   (Final data collection date for primary outcome measure)
half-life of serum 25-hydroxyvitamin D [ Time Frame: up to 12 months ]
Same as current
Complete list of historical versions of study NCT01729013 on ClinicalTrials.gov Archive Site
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Duration of Vitamin D Stores After Prolonged Vitamin D Substitution
Duration of Vitamin D Stores After Prolonged Vitamin D Substitution
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.
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Observational
Observational Model: Cohort
Time Perspective: Prospective
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Retention:   Samples Without DNA
Description:
blood samples and fat biopsy
Non-Probability Sample
Subjects who have previously participated in a vitamin D study
Obesity
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  • subjects previously given placebo
  • subjects previously given vitamin D
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*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Completed
78
August 2015
May 2015   (Final data collection date for primary outcome measure)

Inclusion Criteria:

  • previously participated in a vitamin D study

Exclusion Criteria:

  • pregnancy
Sexes Eligible for Study: All
25 Years to 85 Years   (Adult, Senior)
Yes
Contact information is only displayed when the study is recruiting subjects
Norway
 
 
NCT01729013
Tromsø-Endo-2012-2
No
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University of Tromso
University of Tromso
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Principal Investigator: rolf jorde, professor University of Tromso
University of Tromso
September 2015