Condition category
Circulatory System
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Not provided at time of registration

Trial website

Contact information



Primary contact

Prof Juergen Schrezenmeir


Contact details

Max Rubner-Institute
Federal Research Centre for Nutrition and Food
Hermann-Weigmann-Str. 1
+49 (0)431 609 2220

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title



Study hypothesis

Conjugated 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

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)

Study design

Single centre, randomised double-blind placebo-controlled intervention study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting

Not specified

Trial type


Patient information sheet


Cardiovascular disease


Group 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 type



Not Specified

Drug names

Conjugated linoleic acid (CLA), safflower oil, native olive oil

Primary outcome measure

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

Secondary outcome measures

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.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. 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

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. 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

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Max Rubner-Institute

Sponsor information


Max Rubner Institute (Germany)

Sponsor details

c/o Prof. Juergen Schrezenmeir
Federal Research Centre for Nutrition and Food
Haid-und-Neu-Str. 9
+49 (0)721 6625 400

Sponsor type

Research organisation



Funder type


Funder name

Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung [BMBF]) (Germany)

Alternative name(s)

Federal Ministry of Education and Research, BMBF

Funding Body Type

government organisation

Funding Body Subtype

National government



Funder name

Federal Ministry of Food, Agriculture and Consumer Protection (Bundesministerium für Ernährung, Landwirtschaft und Verbraucherschutz) (Germany)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

Cognis GmbH (Germany)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

1. 2011 results in

Publication citations

  1. Results

    Pfeuffer M, Fielitz K, Laue C, Winkler P, Rubin D, Helwig U, Giller K, Kammann J, Schwedhelm E, Böger RH, Bub A, Bell D, Schrezenmeir J, CLA does not impair endothelial function and decreases body weight as compared with safflower oil in overweight and obese male subjects., J Am Coll Nutr, 2011, 30, 1, 19-28.

Additional files

Editorial Notes