Getting Vitamin D Dosing Right
Condition: Vitamin D Status
Study type: Interventional

Summary: 
      The investigators want to make sure that people get the right dose of Vitamin D treatment.
      They will therefore investigate how skin colour, body mass index, ethnicity, vitamin D
      binding protein and genetic variation affect the response to a standard course of vitamin D
      in young adults, as a prelude to further studies in younger children.
    

Detailed description: 
      The Department of Health and the Chief Medical Officer have identified vitamin D deficiency
      as a key area of interest and concern for public health.

      The main function of vitamin D is to enable dietary calcium to be absorbed from the
      intestine. Low levels of vitamin D can lead to diseases of bone such as rickets and
      osteomalacia and are linked to a higher risk of fracturing bones in older women with
      osteoporosis.

      Vitamin D levels may be affected by the skin colour, body mass index (BMI), lifestyle or
      environment in which someone lives, and by their genetic makeup. Vitamin D levels tend to be
      lower in people with higher BMI and / or darker coloured skin or if the skin is covered by
      clothing because a lot of vitamin D is made from the action of sunlight on natural chemicals
      in the skin.

      Vitamin D does occur naturally in the diet in foods like oily fish, and also vitamin D can be
      given as a supplement either on its own or as part of a multivitamin tablet.

      There is natural variation from one person to another in how well the system controlling
      vitamin D blood levels works. Vitamin D circulates bound to a carrier protein, vitamin D
      binding protein (VDBP). When vitamin D levels are measured, both vitamin D bound to the
      protein and "free" vitamin D are measured.

      A recent study in America showed that when "free" vitamin D levels (total vitamin D minus
      vitamin D bound to VDBP) are measured, they correlate very closely with other factors that
      help determine blood calcium levels.This variation is determined in part by a person's
      genetic makeup, and recent large studies have identified specific genetic variations that are
      linked to blood levels of vitamin D; some of these vary with the person's ethnic origin.

      At present if someone has low vitamin D levels that put them at increased risk of bone
      problems, a course of vitamin D treatment is given.

      When the investigators assessed their regular treatment given to children recently, they
      found some individuals developed very high blood vitamin D levels and others didn't.

      They don't know how VDBP levels affect the response to treatment with vitamin D.

      Further variation can occur because of the distribution of vitamin D into fat tissue. The
      investigators will measure height and weight, and waist and hip circumference and calculate
      Body Mass Index, body surface area (BSA) and waist: hip ratio as proxy measures of fat mass.

      They will also evaluate whether blood or saliva tests give better information about vitamin D
      levels. The information about how these factors affect the response to vitamin D will help
      the clinicians choose the right dose of vitamin D for studies in younger children who are
      still growing.
    

Intervention name(s): Vitamin D
Intervention type(s): Dietary Supplement
Intervention description(s): 150,000 IU of Vitamin D3 Oral solution
Intervention MeSH terms: Vitamin D
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic