Conjugated Linoleic Acid (CLA) is a polyunsaturated fat naturally found in meat and dairy products. CLA Supplements have been the subject of extensive scientific investigation due to their potential benefits in weight loss and body composition improvement. However, despite promising results in animal studies, research in humans has yielded mixed outcomes, raising questions about its efficacy and safety.
The History of CLA Supplements
The initial enthusiasm surrounding CLA supplementation stemmed from early animal studies conducted in 2007. These studies, particularly in mice, demonstrated modest reductions in body fat, sparking interest in its potential application for humans. This early promise led to the development and widespread use of CLA supplements, aiming to replicate these benefits in human populations.
Mixed Results in Human Studies
Despite encouraging animal research, human studies have not consistently supported the efficacy of CLA supplements.
-
Studies Highlighting Limited Effects:
- A 2011 study reported no significant changes in body weight or composition after an eight-week CLA supplementation protocol.
- In 2012, a meta-analysis of 15 randomized controlled trials found slight fat loss compared to a placebo. However, the authors deemed these differences clinically insignificant, urging caution in interpreting the results.
- Recent Findings:
More recent meta-analyses have suggested a slight reduction in body weight with CLA supplements, but the effects remain minimal. Researchers emphasize that these small changes may not translate into meaningful clinical benefits.
Potential Side Effects of CLA Supplements
While CLA supplements may offer minor benefits, they are not without risks. Different isomers of CLA are associated with varied effects, including both fat loss and adverse outcomes such as increased liver fat and insulin resistance. Commonly reported side effects in human studies include:
- Gastrointestinal issues such as constipation and diarrhea
- Increased inflammation and oxidative stress in some participants
Given these potential side effects, the safety of CLA supplements—particularly for long-term use—remains uncertain.
Expert Insights
Natalie Adair Suazo, Chief Science Officer at Fitbliss Fitness, highlights the need for caution when considering CLA supplements. While some studies indicate potential health benefits, the inconsistency in human research and the presence of side effects make it difficult to recommend CLA confidently.
A comprehensive review in 2015 echoed these sentiments, noting that promising results from animal studies often fail to translate to human trials. Researchers continue to call for more robust human studies to determine the efficacy and safety of CLA supplements.
Conclusion
A 2015 comprehensive review echoed the uncertainty, stating that promising animal study results did not consistently translate to human trials. In conclusion, Suazo acknowledged that while CLA might offer some health benefits and potential for fat reduction, mixed research outcomes and potential side effects raise concerns about confidently recommending it. Especially for long-term use, caution is advised until more human trials provide clearer evidence.
References:
Benjamin, S., Prakasan, P., Sreedharan, S., Wright, A.-D. G., & Spener, F. (2015). Pros and cons of CLA consumption: an insight from clinical evidences. Nutrition & Metabolism, 12(1), 4. https://doi.org/10.1186/1743-7075-12-4
Joseph, S. V., Jacques, H., Plourde, M., Mitchell, P. L., McLeod, R. S., & Jones, P. J. H. (2011). Conjugated linoleic acid supplementation for 8 weeks does not affect body composition, lipid profile, or safety biomarkers in overweight, hyperlipidemic men. The Journal of Nutrition, 141(7), 1286–1291. https://doi.org/10.3945/jn.110.135087
Namazi, N., Irandoost, P., Larijani, B., & Azadbakht, L. (2019). The effects of supplementation with conjugated linoleic acid on anthropometric indices and body composition in overweight and obese subjects: A systematic review and meta-analysis. Critical Reviews in Food Science and Nutrition, 59(17), 2720–2733. https://doi.org/10.1080/10408398.2018.1466107
Onakpoya, I. J., Posadzki, P. P., Watson, L. K., Davies, L. A., & Ernst, E. (2012). The efficacy of long-term conjugated linoleic acid (CLA) supplementation on body composition in overweight and obese individuals: a systematic review and meta-analysis of randomized clinical trials. European Journal of Nutrition, 51(2), 127–134. https://doi.org/10.1007/s00394-011-0253-9
Whigham, L. D., Watras, A. C., & Schoeller, D. A. (2007). Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. The American Journal of Clinical Nutrition, 85(5), 1203–1211. https://doi.org/10.1093/ajcn/85.5.1203

Leave a Comment