Mono-centred, randomised, placebo-controlled, double-blind parallel-arm study on the effect of Conjugated Linoleic Acid (CLA) on endothelial function and (postprandial) metabolic parameters in overweight men

ISRCTN ISRCTN30870177
DOI https://doi.org/10.1186/ISRCTN30870177
Protocol serial number N/A
Sponsor Max Rubner Institute (Germany)
Funders Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung [BMBF]) (Germany), Federal Ministry of Food, Agriculture and Consumer Protection (Bundesministerium für Ernährung, Landwirtschaft und Verbraucherschutz) (Germany), Cognis GmbH (Germany)
Submission date
03/09/2008
Registration date
17/10/2008
Last edited
03/01/2012
Recruitment status
No longer recruiting
Overall study status
Completed
Condition category
Circulatory System
Prospectively registered
Protocol
Statistical analysis plan
Results
Individual participant data

Plain English summary of protocol

Not provided at time of registration

Contact information

Prof Juergen Schrezenmeir
Scientific

Max Rubner-Institute
Federal Research Centre for Nutrition and Food
Hermann-Weigmann-Str. 1
Kiel
24103
Germany

+49 (0)431 609 2220
juergen.schrezenmeir@mri.bund.de

Study information

Primary study designInterventional
Study designSingle centre, randomised double-blind placebo-controlled intervention study
Secondary study designRandomised controlled trial
Scientific title
Study acronymCLA1
Study objectivesConjugated linoleic acid (CLA) may beneficially affect lipid and glucose metabolism, inflammatory responses and body weight. These aspects are of relevance for subjects afflicted with or prone to develop a so-called metabolic syndrome, which is characterised by an insulin resistance, dyslipidaemia, essential hypertension and adiposity of the central type and frequently leads to early manifestation of type 2 diabetes mellitus, increased vascular risk and risk of atherosclerosis. This study examines the influence of dietary conjugated linoleic acid (CLA) (commercially available 50:50 mixture of isomers cis9,trans11-CLA and trans10,cis12-CLA) on endothelial function and below mentioned fasting and postprandial metabolic parameters in comparison to safflower oil. For explorative purposes two more groups are given native olive oil or heated (thermally oxidised) safflower oil. Tocopherol concentration of the supplements is adjusted to that of safflower oil. Further parameters to judge pro-atherogenic processes are soluble adhesion molecules (intercellular adhesion molecule [ICAM], vascular cell adhesion molecule [VCAM], E-Selectin) which promote inflammatory processes by initiating the adherence of leukocytes and monocytes to the endothelium of blood vessels.
Ethics approval(s)Ethics approval received from the Ethics Committee of the Medical Faculty of the Christian-Albrechts-University of Kiel (Germany) on the 13th April 2006 (ref: A 106/06)
Health condition(s) or problem(s) studiedCardiovascular disease
InterventionGroup 1: CLA 50:50 isomer mixture (cis9,trans11-CLA: trans10,cis12-CLA)
Group 2: safflower oil
Group 3: native olive oil
Group 4: safflower oil - thermally oxidised

Supplements given two times a day during breakfast (or lunch) and dinner, four capsules each, making a total dose per day of eight capsules (= 4.5 g). Total duration of treatment was 4 weeks (28 + 2 days), for all four treatments.

Follow up:
Start of the follow up period, i.e. start of the intervention for the first study subjects was 24/04/2006. End of the trial follow-up period was 02/08/2006.
Intervention typeDrug
PhaseNot Specified
Drug / device / biological / vaccine name(s)Conjugated linoleic acid (CLA), safflower oil, native olive oil
Primary outcome measure(s)

Changes in endothelial function: PAT-Index after 28(± 2) days supplementation.

Key secondary outcome measure(s)

1. Body mass index (BMI)
2. Waist circumference (WC)
3. Waist to hip ratio (WHR)
4. Blood pressure, pulse

Changes in:
5. Fasting and postprandial triglycerides (AUC)
6. Fasting and postprandial insulin (AUC)
7. Fasting and postprandial glucose (AUC)
8. Homeostasis model assessment of insulin resistance (HOMA-IR) (insulin-glucose-product)
9. HOMA-b-cell-function
10. Lipids, namely total, low density lipoprotein (LDL-) and high density lipoprotein (HDL-) cholesterol
11. Oxidative modification of lipids and oxidative stress, namely: oxidised LDL, isoprostanes
13. Inflammatory parameters, namely: C-reactive protein (CRP), soluble vascular cell adhesion molecule (sVCAM), soluble intercellular adhesion molecule (sICAM), soluble E-selectin, interleukin-6 (IL-6), tumour necrosis factor alpha (TNF alpha), monocyte chemoattractant protein-1 (MCP-1)
14. Other regulators/hormones: adiponectin, leptin, ghrelin, glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), vascular endothelial growth factor (VEGF)

All secondary parameters were determined both at start of the intervention (day 0) and end of the study, i.e. after 4 weeks. Treatment-induced changes were calculated and compared between intervention groups.

Completion date02/08/2006

Eligibility

Participant type(s)Patient
Age groupAdult
SexMale
Target sample size at registration88
Key inclusion criteria1. Healthy male volunteers
2. Aged 45 - 68 years
3. Body mass index (BMI) 25 - 29 kg/m^2
4. Member of the Metabolic Intervention Cohort Kiel (MICK)
5. Written informed consent
Key exclusion criteria1. Participation in a clinical study with a medicament or a medicinal product within the last 30 days or simultaneous participation in another clinical examination
2. Inability to understand and to comply with the study protocol
3. Known metabolic or gastro-intestinal diseases, which affect the absorption, metabolism or excretion of food or food components
4. Condition after surgery of the gastro-intestinal tract, which affects gastro-intestinal motility
5. Haemoglobin less than 12 g/dL
6. Latex allergy
7. Diabetes (fasting glucose levels greater than 125 mg/dl after repeated determination)
8. Surgery within the last 3 months, which still affects the current state of health
9. Intake of nitrate and/or calcium antagonists, which affect the blood pressure
10. Deformation of finger tips, which inhibits correct recording of EndoPAT (measures a Peripheral Arterial Tone [PAT™] signal for assessment of endothelial dysfunction)
11. Illness of thyroid gland, which has metabolic and/or cardiovascular effect
12. Known hepatitis B, hepatitis C, human immunodeficiency virus (HIV) infection or chronic liver disease
13. Kidney malfunction
14. Psychiatric disorders, epilepsy, risk of suicide
15. Drug or alcohol abuse
16. Intake of drugs affecting the absorption, metabolism or excretion of food components or the gastro-intestinal motility
17. Intake of hormone preparations, particularly cortisone
18. Eating disorders, anorexia, bulimia, unusual outsider dietary habits
19. Legal incapacity
20. Others depending on the judgement of the study physician
Date of first enrolment18/04/2006
Date of final enrolment02/08/2006

Locations

Countries of recruitment

  • Germany

Study participating centre

Max Rubner-Institute
Kiel
24103
Germany

Results and Publications

Individual participant data (IPD) Intention to shareNo
IPD sharing plan summaryNot provided at time of registration
IPD sharing plan

Study outputs

Output type Details Date created Date added Peer reviewed? Patient-facing?
Results article results 01/02/2011 Yes No
BMC - Part of Springer Nature Springer Nature