Adherence to Mediterranean diet can reduce the risk of obesity in people with genetic predisposition to obesity
| ISRCTN | ISRCTN15898185 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN15898185 |
| Secondary identifying numbers | Research Institute for Endocrine Sciences (Grant No. 840), Shahid Beheshti University of Medical Sciences |
- Submission date
- 23/07/2017
- Registration date
- 02/08/2017
- Last edited
- 20/09/2023
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Nutritional, Metabolic, Endocrine
Plain English summary of protocol
Background and study aims
The obesity epidemic worldwide is fast increasing and affecting individuals of all ages, races and both genders. It is related with a series of other issues including diabetes, hypertension, cancer and cardiovascular diseases. Obesity is caused by genetic and environmental factors such as over-consumption of energy and sedentary lifestyle. Of genetic variants, fat mass and the obesity associated gene (FTO) have been found to be consistently associated with obesity traits in several populations. However there is increasing interest in finding out whether lifestyle factors modify the association of FTO variants and obesity as this could better provide insight into the role of diet/environmental factors in obesity. The Mediterranean diet is a diet that is high in vegetables, olive oil and fish (lean sources of protein). A higher adherence to the Mediterranean dietary pattern (Med Diet) using Mediterranean diet scores (MDS) has been associated with a decrease in obesity, regardless of genetic risk. This study uses participants in the Tehran Lipid and Glucose Study (TLGS). The TLGS is a large-scale, community-based, prospective study being performed on a sample of residents of District 13 of Tehran, capital of Iran. The first phase of the TLGS was conducted from 1999 to 2001 and follow-up examinations have been conducted every 3 years (2002–2005; 2006–2008; 2008–2011, and 2011–2014) to identify newly developed diseases. The aim of this study is to investigate whether Med Diet could interact with FTO in relation to obesity among adult participants in order to identify environmental interactions to create preventive approaches in individuals with greater genetic susceptibility to obesity.
Who can participate?
Adults aged 18 years and older.
What does the study involve?
Participants undergo a baseline survey. Those who are evaluated as obese are excluded. The other participants are followed and randomly selected for follow-up surveys.The surveys include questions about food frequency and types of food ingested in order to provide a MDS score to participants. Other measures such as physical activity, smoking, and other demographics are also assessed. DNA samples are provided by participants in order to identify their genetic risk.
What are the possible benefits and risks of participating?
Participants may help prevent obesity in those with FTO risk alleles. There are no risks with participating.
Where is the study run from?
This study is run by the Shahid Beheshti Univeristy of Medical Sciences (Iran) and the TLGS is performed on a sample of residents of District 13 of Tehran (Iran).
When is the study starting and how long is it expected to run for?
February 1998 to February 2017
Who is funding the study?
Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences (Iran)
Who is the main contact?
Parvin Mirmiran, Prof.
mirmiran@endocrine.ac.ir
Contact information
Scientific
Nutrition and Endocrine Research Centre
Research Institute for Endocrine Sciences
Shahid Beheshti University of Medical Sciences
No.24, Arabi Street
Yemen Avenue
Chamran Highway
Tehran
1985717413
Iran
 ORCID ID |
0000-0002-9697-0081 |
|---|---|
| Phone | +98 212 243 2500 |
| f.hosseini@sbmu.ac.ir |
Scientific
Nutrition and Endocrine Research Centre
Research Institute for Endocrine Sciences
Shahid Beheshti University of Medical Sciences
No.24, Arabi Street
Yemen Avenue
Chamran Highway
Tehran
1985717413
Iran
| ORCID ID |
0000-0003-2391-4924 |
|---|---|
| Phone | +98 212 243 2500 |
| mirmiran@endocrine.ac.ir |
Study information
| Study design | Observational-nested case-control study |
|---|---|
| Primary study design | Observational |
| Secondary study design | Nested case-control study |
| Study setting(s) | Community |
| Study type | Other |
| Scientific title | Mediterranean dietary pattern adherence modify the association between FTO genetic variations and obesity phenotypes |
| Study objectives | Can Mediterranean Diet interact with FTO gene polymorphisms (rs1121980, rs1421085, rs9939973, rs8050136, rs17817449 and rs3751812) in isolation or combined form (GRS) in relation to obesity phenotypes among participants of the Tehran Lipid and Glucose Study (TLGS)? |
| Ethics approval(s) | Ethics committee of the Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, 10/01/1999, ref: 840 |
| Health condition(s) or problem(s) studied | Obesity |
| Intervention | Participants undergo a baseline survey. Those who are evaluated as obese are excluded. The other participants are followed and randomly selected for follow-up surveys between 2006-2008, 2008-2011 and 2011-2014. Each of these cases are individually paired and matched by age (plus or minus five years), sex and duration of follow-up with a random control from a population with normal body mass index. The duration of follow-up is from baseline to the follow up survey which marks the end of their participation in the study. The survey that participants fill out assessed participants dietary intakes using a valid and reliable 168-item semi-quantitative food frequency questionnaire (FFQ) at baseline and follow up surveys. The Mediterranean dietary score is computed according to richopoulou et al. based on the following eight components: Legumes, vegetables, nuts and fruits, fish, and cereals intake; dietary ratio of monounsaturated fatty acid (MUFA) to saturated fatty acid (SFA); intake of dairy products, mostly in the form of cheese or yogurt and intakes of meat and poultry. The anthropometric, physical activity, smoking and the other demographic variables are assessed at baseline and follow-up surveys, DNA products of participants were genotyped and genetic risk score is computed. The risk of obesity (odds ratio) of individuals with different genetic risk scores assessed across the Mediterranean dietary score quartiles from baseline to follow-up survey. |
| Intervention type | Other |
| Primary outcome measure | 1. Weight is measured using the digital scales at baseline and each follow-up examination (every three years) 2. Height is measured using a tape measure at baseline and each follow-up examination (every three years) 3. Waist circumference is measured using the upstretched tape meter at baseline and each follow-up examination (every three years) 4. Hip circumference is measured using the upstretched tape meter at baseline and each follow-up examination (every three years) |
| Secondary outcome measures | 1. BMI (body mass index) is calculated by dividing weight in kilograms on height in meters squared baseline (kg/m2) at baseline and each follow-up examination (every three years) 2. WHR (waist to hip ratio) is calculated by dividing waist on hip circumferences at baseline and each follow-up examination (every three years) 3. Obesity was defined as a BMI ≥30 kg/m2 4. BMI between 18.5 and 24.9 classified a person as having a normal weight 5. Waist circumference >95 cm for both genders was considered as indicators of abdominal obesity 6. WHR >0.8 in men and >0.9 in women, was considered as indicators of abdominal obesity |
| Overall study start date | 01/02/1998 |
| Completion date | 15/02/2017 |
Eligibility
| Participant type(s) | Mixed |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Sex | Both |
| Target number of participants | 627 pairs of persons with obesity and their matched controls (1254 persons) |
| Total final enrolment | 1000 |
| Key inclusion criteria | 1. Age ≥18 years 2. Both genders 3. Participating in baseline and follow-up examinations of Tehran Lipid and Glucose Study 4. BMI≥30 for cases, BMI≥18.5 and <25 for controls. 5. Not pregnant or lactating women 6. Not history of weight loss or gain >5 kg in the last 6 months 7. Not taking drugs that affect weight 8. Not under or over-reporters of energy intake 9. DNA purification in the range of 1.7<A260/A280<2 |
| Key exclusion criteria | 1. Individuals with a history of weight loss or gain >5 kg in the last 6 months 2. Pregnant and lactating 3. Taken drugs that affect weight 4. Cases/controls lacking DNA purification in the range of 1.7<A260/A280<2 5. Reported energy intakes divided by the predicted energy intake did not qualify for the ±3SD range |
| Date of first enrolment | 31/01/1999 |
| Date of final enrolment | 20/01/2015 |
Locations
Countries of recruitment
- Iran
Study participating centre
Research Institute for Endocrine Sciences
No. 24, Arabi Street
Yemen Anenue
Chamran highway
Tehran
1985717413
Iran
Sponsor information
Research organisation
Nutrition and Endocrine Research Centre
Research Institute for Endocrine Sciences
No. 24, Arabi Street
Yemen Avenue
Chamran Highway
Tehran
1985717413
Iran
| Phone | +98 212 243 2500 |
|---|---|
| mirmiran@endocrine.ac.ir | |
"ROR" |
https://ror.org/034m2b326 |
Funders
Funder type
Not defined
Government organisation / Universities (academic only)
- Alternative name(s)
- Shahid Beheshti University of Medical Sciences (SBMU), Iran, Shahid Beheshti University of Medical Sciences (Iran), Shahid Beheshti University of Medical Sciences - Iran, دانشگاه علومپزشکی شهید بهشتی, Université des Sciences Médicales de Shahid Beheshti, جامعة شهيد بهشتي للعلوم الطبية, Shahid Beheshti University of Medical Sciences Tehran Iran, Shahid Beheshti University of Medical Sciences Tehran, Université des Sciences Médicales de, دانشگاه علوم پزشکی و درمانی شهید بهشتی, جامعة شهيد بهشتي للعلوم, SBUMS
- Location
- Iran
Results and Publications
| Intention to publish date | 15/08/2017 |
|---|---|
| Individual participant data (IPD) Intention to share | Yes |
| IPD sharing plan summary | Available on request |
| Publication and dissemination plan | Phase one and two have been published. The manuscript is planned to submit in American Journal of Clinical Nutrition as soon as we receive Clinical Trial Registration Number. |
| IPD sharing plan | The datasets generated during and/or analysed during the current study are/will be available upon request from Dr. Amir-Abbas Momenan at momenan@gmail.com or momenan@endocrine.ac.ir |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Results article | results (phase one) | 01/05/2002 | Yes | No | |
| Results article | results (phase two) in | 25/01/2009 | Yes | No | |
| Results article | 26/09/2017 | 20/09/2023 | Yes | No |
Editorial Notes
20/09/2023: Publication reference and total final enrolment added.
25/09/2017: Internal review.
