Pros and Cons of CLA Consumption: An Insight From Clinical Evidences

Sailas Benjamin; Priji Prakasan; Sajith Sreedharan; Andre-Denis G Wright; Friedrich Spener


Nutr Metab. 2015;12(4) 

In This Article


As far as the voluminous literature on CLA is concerned, only a few studies to date examined the effects of CLA in humans in vivo. However, results of these studies do not reflect the dramatic and consistent data demonstrated in animal studies. Thus, these disappointing results in humans demand more precise experimentations with humans. The interest in CLA research still persists, and hence, many questions related to the safety and efficacy on the consumption CLA have to be answered scientifically. Hence, it is imperative to critically evaluate and consolidate prominent findings on human consumption of CLA, i.e., the principal actions of this minor lipid nutrient exerting on human system so that future investigations would focus on specific CLA isomers and the most reasonable mechanism of action due to them. One of the major limitations in human studies is that most of the studies depend only on the blood cells or plasma, and fat deposition. Thus, majority of the clinical studies failed to provide conclusive evidences for the effectiveness of CLA on human health, except for anti-obesitic properties which offered a little hope to prevent body weight regain though fat deposition, nevertheless increased oxidative stress and insulin resistance due to such over-consumption of CLA poses contradictory concerns. Moreover, age, gender, genetic polymorphism and immune status of the subject, role of other nutrients present in the diet, and extend of absorption of individual isomers to different tissues have to be well addressed during the intervention period – so as to evaluate the safety and efficacy of CLA consumption on human health. As far as human consumption of CLA is concerned, a definite conclusion for safety and efficacy has not been reached yet. At this context, we strongly recommend the need for more precise and well-designed long-term intervention studies with controlled food intake and activity level to assess the effectiveness of CLA on human health. Moreover, such studies need to be duplicated in other laboratories giving emphasis to men and women, age group, ethnic background, food style, continental and even national uniqueness, cultural and geographic barriers, etc. without comparing data from animal studies – i.e., a real double-blind clinical study. In toto, clinical evidences indicate a possible link of supplemental CLA per se toward negative or inconclusive outcomes; thus, inclusion of CLA in the Codex Alimentarius (Book of Food) – which describes internationally recognized standards of food – may be considered.