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[Can linoleic acids in conjugated CLA products reduce overweight problems?]
Margaretha Haugen1, Jan Alexander
1Avdeling for naeringsmiddeltoksikologi, Divisjon for miljømedisin, Nasjonalt folkehelseinstitutt, Postboks 4404 Nydalen, 0403 Oslo. margaretha.haugen@fhi.no
Summary
Conjugated linoleic acid (CLA) supplements show no weight loss benefits in humans, despite animal studies. CLA may negatively impact metabolism and health, particularly in pregnant women.
Area of Science:
- Nutritional Science
- Human Physiology
- Metabolic Health
Context:
- Conjugated linoleic acid (CLA) supplements are marketed for weight reduction and body composition improvement.
- Scientific evidence supporting these claims in humans is limited and often contradictory.
- Safety and adverse effects of CLA supplementation require thorough investigation.
Purpose:
- To critically evaluate the scientific evidence for the efficacy and safety of CLA supplementation.
- To assess the impact of CLA on weight, body composition, and metabolic health in humans.
- To identify potential adverse effects associated with CLA intake.
Summary:
- Animal studies suggest CLA reduces fat mass and increases muscle mass, but 13 human clinical trials failed to confirm these effects.
- Specific CLA isomers, like 10-trans,12-cis, may impair carbohydrate and lipid metabolism, leading to insulin resistance and hyperlipidemia.
- CLA supplementation in lactating women reduced milk fat content, and maternal CLA levels correlated with shorter gestational length and lower birth weight.
Impact:
- The purported weight and fat mass reduction effects of CLA in humans lack robust scientific support.
- Potential adverse metabolic effects, including insulin resistance and hyperlipidemia, may arise from CLA's mechanism of action via PPARgamma.
- CLA supplementation may pose risks, particularly for pregnant and lactating women, affecting milk composition and fetal development.