Genetic polymorphisms in a beta-carotene metabolising enzyme

ISRCTN ISRCTN45245618
DOI https://doi.org/10.1186/ISRCTN45245618
Secondary identifying numbers 7413
Submission date
12/05/2010
Registration date
12/05/2010
Last edited
31/10/2019
Recruitment status
No longer recruiting
Overall study status
Completed
Condition category
Other
Prospectively registered
Protocol
Statistical analysis plan
Results
Individual participant data
Record updated in last year

Plain English summary of protocol

Not provided at time of registration

Contact information

Dr Georg Lietz
Scientific

School of Agriculture, Food and Rural Development (AFRD)
University of Newcastle
Kings Road
Newcastle upon Tyne
NE1 7RU
United Kingdom

Study information

Study designSingle centre non-randomised interventional trial
Primary study designInterventional
Secondary study designNon randomised controlled trial
Study setting(s)Other
Study typeTreatment
Participant information sheet Not available in web format, please use the contact details below to request a patient information sheet
Scientific titleDo genetic polymorphisms in a beta-carotene metabolising key enzyme influence dietary vitamin A requirements?
Study objectivesVitamin A (retinol) is an essential nutrient for vision, embryonic development, maturity of organs, cellular proliferation andthe immune response. It is obtained from the diet per se or through provitamin A sources that are cleaved enzymatically
in the body to produce retinol. Vitamin A deficiency occurs largely due to increases in physiological requirements (growth, pregnancy, lactation, infection) together with a low dietary intake.

Currently, the mean daily intake of vitamin A is below the recommended intake levels for men and women aged 19 to 24 years. This means that young individuals in the UK rely to over 50% on provitamin A sources, beta-carotene being the main one, to cover their vitamin A needs. Since a significant proportion of young British individuals have a low vitamin A intake and since the Expert Group on Vitamins and Minerals has recommended to limit the use of beta-carotene in food supplements, there is growing concern that young men and women in the UK might develop subclinical deficiencies, therefore increasing their susceptibility to infectious diseases. This concern is especially valid for young pregnant women who will experience a higher physiological need for vitamin A.

Given the fact that a high proportion of the British population relies on beta carotene to cover their vitamin A needs, it is important to note that the amount of retinol produced after ingestion and conversion of beta-carotene is highly variable between healthy individuals. Several studies have shown a large disparity between individuals who are efficient or inefficient converters of beta-carotene, with variations of up to 8-fold. It is possible that the observed differences in obtaining retinol from beta-carotene may be due to genetic polymorphisms in genes involved in aspects of beta-carotene conversion. Indeed, results from our laboratory have shown that two genetic variants exists in the key enzyme responsible for beta-carotene conversion.
Ethics approval(s)Newcastle and North Tyneside Local Research Ethics Committees approved on the 19th May 2009 (ref: 09/H0904/20)
Health condition(s) or problem(s) studiedTopic: Generic Health Relevance and Cross Cutting Themes; Subtopic: Generic Health Relevance (all Subtopics); Disease: Public Health Research
InterventionThe intervention will last 14 days. However, first contact with the study participants will be 2 months prior to the start of the intervention to explain the study. A capsule containing 2 mg dose of beta-carotene and 1 mg retinyl acetate stable isotope will be orally adminstered to volunteers on day 1. Blood samples will be drawn at 7 time points on day 1, with subsequent samples being taken on days 2, 3, 7, and 14.
Intervention typeOther
Primary outcome measureBlood concentrations of administered beta-carotene/retinyl acetate, and derived metabolites. Primary outcome measures will be taken at 0, 2, 4, 6, 8, 12 hours on day 1. Then at days 2, 3, 7, and 14.
Secondary outcome measuresNo secondary outcome measures
Overall study start date01/09/2009
Completion date30/06/2010

Eligibility

Participant type(s)Patient
Age groupAdult
Lower age limit18 Years
SexBoth
Target number of participantsPlanned sample size: 200
Key inclusion criteria1. Aged 18 - 45 years
2. Generally fit and healthy adults
3. Males and females
Key exclusion criteria1. Smokers
2. Pregnant females
3. Diabetics
4. Liver disease
5. Gastrointestinal disorders
Date of first enrolment01/09/2009
Date of final enrolment30/06/2010

Locations

Countries of recruitment

  • England
  • United Kingdom

Study participating centre

School of Agriculture, Food and Rural Development (AFRD)
Newcastle upon Tyne
NE1 7RU
United Kingdom

Sponsor information

Newcastle University (UK)
University/education

School of Agriculture Food and Rural Department
Claremont Road
Newcastle Upon Tyne
NE1 7RU
England
United Kingdom

Website http://www.ncl.ac.uk/
ROR logo "ROR" https://ror.org/01kj2bm70

Funders

Funder type

Research council

Biotechnology and Biological Science Research Council (BBSRC) (UK)

No information available

Results and Publications

Intention to publish date
Individual participant data (IPD) Intention to shareNo
IPD sharing plan summaryNot provided at time of registration
Publication and dissemination planNot provided at time of registration
IPD sharing plan

Editorial Notes

31/10/2019: No publications found, verifying study status with principal investigator.
21/07/2016: No publications found, verifying study status with principal investigator.