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An investigation of the dietary requirements for vitamin D
ISRCTN ISRCTN20236112
DOI 10.1186/ISRCTN20236112
ClinicalTrials.gov identifier
EudraCT number
Public title An investigation of the dietary requirements for vitamin D
Scientific title Dietary requirements for vitamin D: an investigation of the relative significance of dietary intake and sunlight on vitamin D status in young and elderly adults
Acronym N/A
Serial number at source N05R0003
Study hypothesis We hypothesise that additional dietary vitamin D is required to prevent nutritional deficiency during winter in young and elderly adults.
Lay summary Not provided at time of registration
Ethics approval Ethics approval received from the University of Ulster Research Ethics Committee on the 22nd March 2006 (ref: REC/06/13)
Study design Double blinded randomised placebo controlled intervention study - multicentre collaboration (University of Ulster and University College Cork)
Countries of recruitment Ireland
Disease/condition/study domain Dietary vitamin D intake and status
Participants - inclusion criteria 1. Consenting adult men and women
2. Aged 20 - 85 years
3. In general good health
Participants - exclusion criteria 1. Severe medical illness
2. Hypercalcaemia
3. Known intestinal malabsorption syndrome
4. Excessive alcohol use
5. Those who took medications known to interfere with vitamin D metabolism
6. Pregnancy or planning to become pregnant during the six months of the intervention
7. Those taking high dose vitamin D-containing supplements for three months before initiation of study
8. Those who over the six-month course of intervention are planning a winter vacation to a location at which either the altitude or the latitude would be predicted to result in significant cutaneous vitamin D synthesis from solar radiation (e.g., a mountain ski resort or a winter sun coastal resort)
Anticipated start date 01/04/2006
Anticipated end date 31/12/2008
Status of trial Completed
Patient information material
Target number of participants 240 from Coleraine and 240 from Cork
Interventions Oral daily supplementation with vitamin D3 of the following doses:
1. Placebo (no treatment)
2. 5 mcg
3. 10 mcg
4. 15 mcg

Supplementation is provided for six months from October to March. There is no additional follow-up. However there is a run-in phase during the preceding summer when participants are asked to keep a diary of sun exposure and activities outdoors. This is assessed in July and August.
Primary outcome measure(s) 1. Serum 25 hydroxyvitamin D concentrations
2. Serum parathyroid hormone concentrations
3. Serum calcium concentrations
4. Dietary calcium and vitamin D intakes (from four-day food diary and food frequency questionnaire)
Secondary outcome measure(s) 1. Bone mineral density (from dual energy x-ray absorptiometry [DXA] scan of spine, hip and whole body)
2. Body composition measurements
3. Immune markers
4. Bone turnover markers
Sources of funding Food Standards Agency (UK) (ref: N05R0003)
Trial website
Publications 1. 2009 results in http://www.ncbi.nlm.nih.gov/pubmed/19297462
2. 2011 results in http://www.ncbi.nlm.nih.gov/pubmed/21270359
3. 2012 results in http://www.ncbi.nlm.nih.gov/pubmed/22739371
Contact name Prof  Kevin  Cashman
  Address Department of Food and Nutritional Sciences
University College Cork
  City/town Cork
  Zip/Postcode N/A
  Country Ireland
Sponsor Food Standards Agency (UK)
  Address UK Headquarters
Aviation House
125 Kingsway
  City/town London
  Zip/Postcode WC2B 6NH
  Country United Kingdom
  Sponsor website: http://www.food.gov.uk
Date applied 20/12/2007
Last edited 17/10/2012
Date ISRCTN assigned 21/02/2008
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