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Conjugated linoleic acids: why the discrepancy between animal and human studies?
Mélanie Plourde1, Stephanie Jew, Stephen C Cunnane
1Research Center on Aging and Departments of Medicine, and Physiology and Biophysics, Université de Sherbrooke, Sherbrooke, Québec, Canada. melanie.plourde2@usherbrooke.ca
Nutrition Reviews
|August 1, 2008
Summary
Conjugated linoleic acids (CLA) show reduced body fat in animals, but human results vary. Differences in study design, like age and gender, explain this discrepancy in CLA efficacy for weight loss.
Area of Science:
- Nutrition Science
- Human Physiology
- Dietary Supplements
Background:
- Conjugated linoleic acids (CLA) are isomers of linoleic acid.
- Animal studies suggest CLA reduces body fat.
- Human clinical trials show inconsistent results regarding CLA's effect on body fat and weight loss.
Purpose of the Study:
- To review existing literature on CLA and its effects on human body fat and weight.
- To identify reasons for the discrepancy between animal and human study outcomes.
- To explore factors influencing CLA efficacy in humans.
Main Methods:
- Systematic literature review of human clinical trials and animal studies on CLA.
- Analysis of experimental designs, including participant demographics (age, gender), CLA isomers, dosage, and study duration.
- Comparison of methodologies between animal and human research.
Main Results:
- Discrepancies in human and animal data are primarily attributed to methodological differences in study design.
- Factors such as participant age, gender, CLA isomer composition, and dosage significantly influence CLA efficacy.
- The metabolic fate of CLA in humans remains incompletely understood, potentially contributing to inconsistent findings.
Conclusions:
- Methodological variations in human trials are key to understanding inconsistent CLA effects on body composition.
- Further research is needed to elucidate CLA metabolism in humans and optimize its application for weight management.
- Standardizing study designs is crucial for reliable CLA research.
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