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Completed

NCT Number: NCT00780247

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.

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Key information

Conditions

Vitamin D Deficiency Avitaminosis Deficiency Diseases Malnutrition Nutrition Disorders Nutritional and Metabolic Diseases

Age range

18 year–60 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Alaska Kidney and Diabetes Associates

Anchorage, Alaska, 99508, United States

About this study

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).

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Primary outcomes

  1. To measure the prevailing 25D and Vitamin D levels in communities at diverse latitudes

    Time frame: crosssectional

Secondary outcomes

  1. 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.

    Time frame: cross sectional

  2. To collect a blood sample for DNA analysis of inter-individual differences in Vitamin D metabolism (Gc or Vitamin D binding protein alleles).

    Time frame: cross sectional

Sponsors and collaborators

Lead sponsor

Creighton University

Other

Collaborators

  • Procter and Gamble

Registry information

Acronym: Alaska/Hawaii

Important dates

Study start
2008
Primary completion
2008
Study completion
2008
First posted
Oct 27, 2008
Registry last updated
Oct 27, 2008

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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