Genetic polymorphisms in a beta-carotene metabolising enzyme
| ISRCTN | ISRCTN45245618 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN45245618 |
| Protocol serial number | 7413 |
| Sponsor | Newcastle University (UK) |
| Funder | Biotechnology and Biological Science Research Council (BBSRC) (UK) |
- 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
Scientific
School of Agriculture, Food and Rural Development (AFRD)
University of Newcastle
Kings Road
Newcastle upon Tyne
NE1 7RU
United Kingdom
Study information
| Primary study design | Interventional |
|---|---|
| Study design | Single centre non-randomised interventional trial |
| Secondary study design | Non randomised controlled trial |
| Study type | Participant information sheet |
| Scientific title | Do genetic polymorphisms in a beta-carotene metabolising key enzyme influence dietary vitamin A requirements? |
| Study objectives | Vitamin 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) studied | Topic: Generic Health Relevance and Cross Cutting Themes; Subtopic: Generic Health Relevance (all Subtopics); Disease: Public Health Research |
| Intervention | The 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 type | Other |
| Primary outcome measure(s) |
Blood 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. |
| Key secondary outcome measure(s) |
No secondary outcome measures |
| Completion date | 30/06/2010 |
Eligibility
| Participant type(s) | Patient |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Sex | All |
| Target sample size at registration | 200 |
| Key inclusion criteria | 1. Aged 18 - 45 years 2. Generally fit and healthy adults 3. Males and females |
| Key exclusion criteria | 1. Smokers 2. Pregnant females 3. Diabetics 4. Liver disease 5. Gastrointestinal disorders |
| Date of first enrolment | 01/09/2009 |
| Date of final enrolment | 30/06/2010 |
Locations
Countries of recruitment
- United Kingdom
- England
Study participating centre
School of Agriculture, Food and Rural Development (AFRD)
Newcastle upon Tyne
NE1 7RU
United Kingdom
NE1 7RU
United Kingdom
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|---|
| IPD sharing plan summary | Not provided at time of registration |
| IPD sharing plan |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Participant information sheet | Participant information sheet | 11/11/2025 | 11/11/2025 | No | Yes |
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.
