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 .
Conjugated linoleic acid supplementation reduces peripheral blood mononuclear cell interleukin-2 production in healthy middle-aged males.
Conjugated linoleic acid ( CLA ) refers to geometric and positional isomers of linoleic acid . Animal studies have shown that CLA modulates the immune system and suggest that it may have a therapeutic role in inflammatory disorders . This double-blind placebo-controlled intervention trial investigated the effects of CLA supplementation on indices of immunity relating to cardiovascular disease ( CVD ) in a cohort of healthy middle-aged male volunteers . Subjects were r and omly assigned to supplement their diet with 2.2 g 50:50 isomeric blend of cis 9 , trans 11 ( c9 , t11)-CLA and trans 10 , cis 12 ( t10 , c12)-CLA or placebo daily for 8 weeks . Interleukin ( IL ) 2 , IL-10 and tumour necrosis factor ( TNF ) alpha were measured in the supernatant of cultured unstimulated and concanavalin A ( Con A)-stimulated peripheral blood mononuclear cells ( P BMC ) by ELISA . Serum IL-6 and plasma CRP were measured by ELISA and plasma fibrinogen by automated clotting assay . Gene expression was investigated by real-time RT-PCR . CLA supplementation significantly reduced Con A-stimulated P BMC IL-2 secretion ( 37.1 % ; P=.02 ) . CLA supplementation had no significant effect on transcription of IL-2 .  CLA supplementation had no direct significant effects on P BMC TNFalpha or IL-10 secretion . Other inflammatory markers associated with CVD , including IL-6 , CRP and fibrinogen , were not affected by CLA supplementation . This study showed that CLA supplementation reduced P BMC IL-2 secretion from Con A-stimulated P BMC but lacked effect on other markers of the human inflammatory response
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 .