Condition category
Not Applicable
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

Bundesforschungsanstalt für Ernährung und Lebensmittel
Standort Kiel
Institut für Physiologie und Biochemie der Ernährung
Hermann-Weigmann-Str. 1
+49 (0)431 609 2220

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title


CLA2 (Conjugated linoleic acid 2)

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 so called “metabolic syndrome”, which is characterized 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.

Studies of the influence of dietary CLA, namely the individual isomers cis9,trans11-CLA and trans10,cis12-CLA as well as the commercially available 50:50 mixture of these isomers, as compared to linoleic acid as control, on fasting and postprandial metabolism. The study will test if there are genotype-dependent specific effects of the PPARγ2 P12A polymorphism (P12P versus A12A homozygosity). Expression of genes relevant for inflammation and metabolic regulation will be examined in monocytes independent of a PPARγ2 polymorphism. Further parameters to assess atherogenic processes are the expression of adhesion molecules (ICAM, VCAM, E-Selectin). Low Density Lipoprotein (LDL) will be isolated and tested for adhesion molecules expression on endothelial cells. As another study reported that a mixture of CLA isomers impairs endothelial function, this parameter will be determined in our study, with particular attention for the effect of individual isomers. As dietary fats may acutely change endothelial function, this parameter is tested both in the fasting state and following a fat-rich meal. Genotype-dependent specific effects on fat tissue are to be examined by determining the gene expression profile of the subcutaneous fat tissue. Furthermore the effect of CLA on fecal flora will be assessed.

Ethics approval

Ethic Committee of the Medical Faculty of the Christian-Albrechts-University of Kiel, (Germany), approved on 13.09.2006 (ref: A151/06)

Study design

Randomised, double-blind, placebo-controlled, interventional, crossover study.

Primary study design


Secondary study design

Randomised controlled trial

Trial setting

Not specified

Trial type

Not Specified

Patient information sheet


Not applicable


All participants will consume, in random order, capsules with either the individual isomers cis9,trans11-CLA and trans10,cis12-CLA as well as the commercially available 50:50 mixture of these isomers, and linoleic acid as control. The material is provided as free fatty acids in capsules. Tocopherol content of the preparations is standardized.

Each intervention will last for 4 weeks, interrupted by wash-out periods of 6-9 weeks between the interventions.

Intervention type



Not Specified

Drug names

Conjugated Linoleic Acid

Primary outcome measure

Change of postprandial triglyceride levels (Area Under the Curve [AUC]) after 28 (±2) days supplementation. Postprandial triglyceride levels will be measured at the start of the study and after each intervention period.

Secondary outcome measures

Measurements for the following will be made at the start of the study and after each intervention period.

Changes in:
1. Fasting and postprandial insulin (AUC)
2. Fasting and postprandial glucose (AUC)
3. Endothelial function (PAT-Index)
4. Body Mass Index (BMI)
5. Waist circumference (WC)
6. Waist to hip ratio (WHR)
7. Blood pressure, pulse
8. HOMA (Insulin-glucose-product)
9. Metabolic regulatory parameters, namely:
9.1. Glucose dependent insulinotropic polypeptide (GIP)
9.2. Adipsinresistin
9.3. Cholesteryl Ester Transfer Protein (CETP)
9.4. Adiponectin
9.5. Leptin
9.6. Cholezystokinin (CCK)
9.7. Acylation Stimulating Protein (ASP)
10.1. Lipids and apolipoproteins, namely:
10.2. VLDL, total
10.3. LDL- and HDL-cholesterol
10.4. Lipoprotein a (Lp [a])
10.5 Lipoprotein lipase (LpL)
10.6. Apoliprotein AI, AII, and B100
10.7. Fatty acid pattern in cholesteryl esters
10.8. Phospholipids
11. Oxidative modification of lipids and oxidative stress, namely:
11.1. Oxidised LDL
11.2. isoprostanes
11.3. LDL-induced adhesion molecule expression
11.4. Platelet-Activating Factor (PAF)
11.5. total glutathione in erythrocytes,paraoxonase
11.6. Platelet-Activating Factor AcetylHydrolase (PAF-AH)
12. Inflammatory parameters, namely:
12.1. C-reactive protein (CRP)
12.2. Vascular Cell Adhesion Molecule (VCAM)
12.3. InterCellular Adhesion Molecule (ICAM)
12.4. E-selectin, InterLeukin-6 (IL-6)
12.5. Tumor Necrosis Factor-α (TNFα)
12.6. Monocyte Chemoattractant Protein-1 (MCP-1)
12.7. Vascular Endothelial Growth Factor (VEGF)
13. Gene expression profile in adipocytes (fasting adipocyte biopsy) and monocytes (fasting monocyte isolation) by Random-Zell-RNA-assay: expression of genes which may affect lipid metabolism and inflammatory responses (arteriosclerosis)
14. Fecal flora

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Healthy male volunteers aged 45-68
2. Homozygosis of PPARγ2 P12A polymorphism
3. Member of the Metabolic Intervention Cohort Kiel (MICK)

BMI- matched controls will be recruited.

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 affect gastro-intestinal motility
5. Hemoglobin <12 g/dL
6. Latex allergy
7. Diabetes (fasting glucose levels >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 and/or alpha-blockers, which affect the blood pressure
10. Deformation of finger tips, which inhibits correct recording of EndoPAT
11. Illness of thyroid gland, which has metabolic and/or cardiovascular effect
12. Known hepatitis B, hepatitis C, HIV infection or chronic liver damage
13. Kidney insufficiency
14. Drug or alcohol abuse
15. Intake of drugs affecting the absorption, metabolism or excretion of food components or the gastro-intestinal motility
16. Intake of hormone preparations, particularly cortisone
17. Eating disorders, anorexia, bulimia, unusual outsider dietary habits
18. Psychiatric disorders, epilepsy, risk of suicide
19. For those who participate in adipose tissue biopsy, additionally:
19.1. Known allergies against local anaesthetics
19.2. Heart insufficiency
19.3. Coagulation dysfunction/consumption of drugs which may cause such dysfunctions

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Bundesforschungsanstalt für Ernährung und Lebensmittel, Standort Kiel,

Sponsor information


Federal Research Centre for Nutrition and Food (BfEL) (Germany)

Sponsor details

Haid-und-Neu-Str. 9

Sponsor type




Funder type


Funder name

Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung) (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

2009 results in

Publication citations

  1. Results

    Herrmann J, Rubin D, Häsler R, Helwig U, Pfeuffer M, Auinger A, Laue C, Winkler P, Schreiber S, Bell D, Schrezenmeir J, Isomer-specific effects of CLA on gene expression in human adipose tissue depending on PPARgamma2 P12A polymorphism: a double blind, randomized, controlled cross-over study., Lipids Health Dis, 2009, 8, 35, doi: 10.1186/1476-511X-8-35.

Additional files

Editorial Notes