There was a significant heterogeneity for the impact of CLA  on CRP and IL-6 , but not TNF-α .
Conclusions This meta- analysis showed that CLA supplementation may increase inflammatory markers ( CRP and TNF-α ) .
Background / objectives Conjugated linoleic acid ( CLA ) is a polyunsaturated fatty acid with attractive biological activities .
Numerous studies have been conducted on the inflammation-lowering effects of CLA in in vitro and animal models .
However , the effects of CLA treatment on the inflammatory markers in humans are controversial .
Milk Enriched with Conjugated Linoleic Acid Fails to Alter Blood Lipids or Body Composition in Moderately Overweight, Borderline Hyperlipidemic Individuals
Background : Dietary conjugated linoleic acid ( CLA ) represents a group of positional and geometric isomers of conjugated dienoic derivatives of linoleic acid . The effects of dietary CLA on blood lipids and body composition in humans remain controversial . Objective : To examine whether consumption of milk enriched naturally or synthetically with cis 9 , trans 11 ( c-9 , t-11 ) and trans 10 , cis 12 ( t-10 , c-12 ) CLA isomers alters blood lipid indices , including concentrations of total cholesterol , low-density lipoprotein cholesterol , high-density lipoprotein cholesterol , and triacyglycerol ; indices of liver function including plasma alanine transaminase and total bilirubin ; C-reactive protein ; tumor necrosis factor-alpha ; and body weight and composition in moderately overweight , borderline hyperlipidemic humans . Design : A r and omized , 3-phase , crossover , single-blind clinical trial was carried out in moderately overweight , borderline hyperlipidemic individuals who consumed ( 1 ) milk naturally enriched in CLA ( 4.2 % ) containing c-9 , t-11 only providing 1.3 g/d of CLA ; ( 2 ) milk enriched with a 4.2 % synthetic mixture of t-10 , c-12 and c-9 , t-11 CLA isomers providing 1.3 g/d of CLA ; or ( 3 ) untreated milk as a control providing 0.2 g/d CLA . Dietary phases were each 8 weeks in duration and were separated by 4-week washout periods . Plasma lipid levels were measured in blood sample s collected at the beginning and end of each dietary phase . Magnetic resonance imaging was carried out at the beginning and end of each dietary phase to assess any changes in regional body fat composition . Results : Compared with the control intervention , consumption of the two CLA-enriched milks failed to alter plasma total cholesterol , low-density lipoprotein cholesterol , high-density lipoprotein cholesterol , or triacyglycerol concentrations ; body weight ; or fat composition . CLA consumption did not significantly affect plasma alanine transaminase , total bilirubin , C-reactive protein , or tumor necrosis factor-alpha concentrations . Conclusion : Results from this study fail to support the role of milk enriched naturally with CLA containing c-9 , t-11 or synthetically with c-9 , t-11 and t-10 , c-12 CLA isomers in modulation of lipid profiles or body composition in moderately overweight , borderline hyperlipidemic individuals
There was a significant heterogeneity for the impact of CLA  on CRP and IL-6 , but not TNF-α .
Conclusions This meta- analysis showed that CLA supplementation may increase inflammatory markers ( CRP and TNF-α ) .
Background / objectives Conjugated linoleic acid ( CLA ) is a polyunsaturated fatty acid with attractive biological activities .
Numerous studies have been conducted on the inflammation-lowering effects of CLA in in vitro and animal models .
However , the effects of CLA treatment on the inflammatory markers in humans are controversial .