In a recent interview with Natalie Adair Suazo, Fitbliss Fitness’ Chief Science Officer, we discussed Conjugated Linoleic Acid (CLA). CLA is a polyunsaturated fat found in meat and dairy products. This compound has undergone extensive scientific research in both animals and humans. The focus of such studies was on its potential for weight loss and improving body composition.

The conversation explored the history of CLA supplementation, initially driven by promising results in animal studies. Early research in 2007 suggested a modest loss of body fat in animal participants, specifically mice. These animal studies revealed initial excitement and promise that CLA could produce similar results in human participants. However, human studies produced mixed outcomes.

Human Studies

Throughout the next decade, some human studies would demonstrate slight reductions in body fat, while others showed no significant effects. A 2011 study that found no substantial effects on body weight or composition after an eight-week supplementation protocol. In 2012, a meta-analysis that included 15 randomized controlled trials showed some differences in fat loss compared to a placebo. However, the authors questioned the clinical relevance of the observed effects due to their small magnitude. The efficacy of CLA was considered not clinically significant, emphasizing the need for more research.

Side Effects

While more recent meta-analyses suggest a slight reduction in body weight with CLA, it’s crucial to consider potential side effects. Different isomers of CLA may be associated with either fat loss or increased liver fat and insulin resistance. Common adverse effects reported in human studies include constipation, diarrhea, and digestion issues. Some participants experienced small increases in inflammation and oxidative stress

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