Environmental Influences on Vitamin D Status

Vitamin D deficiency is a common problem. The principal source of vitamin D for humans is solar exposure, with cutaneous synthesis of vitamin D by photoconversion of 7-dehydrocholesterol in the skin to pre-vitamin D3. Latitude, altitude, season, skin pigmentation, and age are recognized factors that influence how much vitamin D can be made by solar exposure. However, the relative influences of each are largely unknown and we cannot reliably answer the question of how much sun exposure an individual needs at various latitudes and at various seasons in order to ensure normal vitamin D status.

Description

Purpose of the study: To determine the effect of environmental influences on Vitamin D status.

Specific Aims

To measure the prevailing 25D and Vitamin D levels in communities at diverse latitudes (Alaska and Hawaii).
To collect information on variables that influence Vitamin D status such as skin color, history of sun exposure and sunscreen use, diet history, vitamin and calcium supplements used, and BMI.
To collect typical food samples from the region for future analysis of their Vitamin D and 25D content.
To collect a blood sample for DNA analysis of inter-individual differences in Vitamin D metabolism (Gc or Vitamin D binding protein alleles).

Status: Completed (N/A). Started on July 1st, 2008. Ended on August 1st, 2008.

Enrollment: 50 subjects

Study Type: Observational

Study Design:

Cohort
Cross-Sectional

Conditions:

Vitamin D Deficiency

Interventions:

Eligibility

Inclusion Criteria:

Able to consent and come for a study visit. Male or female males and females ages 18-60.

Exclusion Criteria:

Unable to consent or come to a visit, taking Vitamin D supplements, anticonvulsants, barbiturates, steroids, having granulomatous disease, or liver or kidney disease as these medications and conditions interfere with Vitamin D metabolism.

Gender: Both
Mininum Age: 18 Years
Maximum Age: 60 Years
Healthy Volunteers: Accepts Healthy Volunteers

Resources

Source: Creighton University

Authority: United States: Institutional Review Board

Locations

Alaska Kidney and Diabetes Associates
Anchorage
Alaska
99508
United States

Officials

Laura A Armas, MD (Principal Investigator, Creighton University)

References

None.

Links

None.

Date Verified: October 1st, 2008
First Received: October 24th, 2008
Last Changed: October 24th, 2008

Information obtained from ClinicalTrials.gov on October 28, 2008. Link to the current ClinicalTrials.gov record.

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