Environmental Influences on Vitamin D Status (Alaska/Hawaii)

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.

Study Overview

• Status: Completed
• Conditions: Vitamin D Deficiency

Detailed Description

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

Specific Aims

1. To measure the prevailing 25D and Vitamin D levels in communities at diverse latitudes (Alaska and Hawaii).
2. 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.
3. To collect typical food samples from the region for future analysis of their Vitamin D and 25D content.
4. To collect a blood sample for DNA analysis of inter-individual differences in Vitamin D metabolism (Gc or Vitamin D binding protein alleles).

• Study Type: Observational
• Enrollment (Actual): 50

Contacts and Locations

Study Locations

• United States
  • Alaska
    • Anchorage, Alaska, United States, 99508
      • Alaska Kidney and Diabetes Associates

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 60 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Age of Subjects: The subjects will be between ages 18-60. The upper age is limited to age 60 as aging skin is less able to make vitamin D, therefore a separate study of elderly people would be more appropriate.

Racial and Ethnic Origin: Both sites have a diverse ethnic and racial population and the subjects will be as representative of the population as possible.

Description

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.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Alaska residents; 50 "healthy" community dwelling males or females.
Hawaiian residents; 50 "healthy" community dwelling males or females at each site

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
To measure the prevailing 25D and Vitamin D levels in communities at diverse latitudes	crosssectional

Secondary Outcome Measures

Outcome Measure	Time Frame
2. To collect information on variables that influence Vitamin D status such to collect information on skin color, history of sun exposure and sunscreen use, diet history, vitamin and calcium supplements used, and BMI.	cross sectional
To collect a blood sample for DNA analysis of inter-individual differences in Vitamin D metabolism (Gc or Vitamin D binding protein alleles).	cross sectional

Collaborators and Investigators

• Sponsor: Creighton University
• Collaborators: Procter and Gamble
• Investigators: Principal Investigator: Laura A Armas, MD, Creighton University

Study record dates

Study Major Dates

• Study Start: July 1, 2008
• Primary Completion (Actual): August 1, 2008
• Study Completion (Actual): August 1, 2008

Study Registration Dates

• First Submitted: October 24, 2008
• First Submitted That Met QC Criteria: October 24, 2008
• First Posted (Estimate): October 27, 2008

Study Record Updates

• Last Update Posted (Estimate): October 27, 2008
• Last Update Submitted That Met QC Criteria: October 24, 2008
• Last Verified: October 1, 2008

More Information

Terms related to this study

• Keywords: Vitamin D; Sun; Vitamin D status; Latitude
• Additional Relevant MeSH Terms: Nutrition Disorders; Avitaminosis; Deficiency Diseases; Malnutrition; Vitamin D Deficiency
• Other Study ID Numbers: Creighton6; WIRB approval 20080712