Duration of Vitamin D Stores After Prolonged Vitamin D Substitution

September 18, 2015 updated by: University of Tromso
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 Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Study Type

Study Type

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Observational

Enrollment (Actual)

Enrollment

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78

Contacts and Locations

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Study Locations

  • Norway
      • Tromsø, Norway, 9037
        • University of Tromsø

Participation Criteria

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Eligibility Criteria

Eligibility Criteria

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Ages Eligible for Study

25 years to 85 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Subjects who have previously participated in a vitamin D study

Description

Inclusion Criteria:

  • previously participated in a vitamin D study

Exclusion Criteria:

  • pregnancy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
subjects previously given placebo
subjects previously given vitamin D

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
half-life of serum 25-hydroxyvitamin D
Time Frame: up to 12 months
up to 12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Tromso

Publications and helpful links

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General Publications

Study record dates

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Study Major Dates

Study Start

Study Start

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November 1, 2012

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 1, 2015

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 1, 2015

Study Registration Dates

First Submitted

First Submitted

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November 13, 2012

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 19, 2012

First Posted (Estimate)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 20, 2012

Study Record Updates

Last Update Posted (Estimate)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 22, 2015

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 18, 2015

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2015

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • Tromsø-Endo-2012-2

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