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 .
An increase in dietary n-3 fatty acids decreases a marker of bone resorption in humans
Human , animal , and in vitro research indicates a beneficial effect of appropriate amounts of omega-3 ( n-3 ) polyunsaturated fatty acids ( PUFA ) on bone health . This is the first controlled feeding study in humans to evaluate the effect of dietary plant-derived n-3 PUFA on bone turnover , assessed by serum concentrations of N-telopeptides ( NTx ) and bone-specific alkaline phosphatase ( BSAP ) .  Subjects ( n = 23 ) consumed each diet for 6 weeks in a r and omized , 3-period crossover design : 1 ) Average American Diet ( AAD ; [ 34 % total fat , 13 % saturated fatty acids ( SFA ) , 13 % monounsaturated fatty acids ( MUFA ) , 9 % PUFA ( 7.7 % LA , 0.8 % ALA ) ] ) , 2 ) Linoleic Acid Diet ( LA ; [ 37 % total fat , 9 % SFA , 12 % MUFA , 16 % PUFA ( 12.6 % LA , 3.6 % ALA ) ] ) , and 3 ) α-Linolenic Acid Diet ( ALA ; [ 38 % total fat , 8 % SFA , 12 % MUFA , 17 % PUFA ( 10.5 % LA , 6.5 % ALA ) ] ) . Walnuts and flaxseed oil were the predominant sources of ALA . NTx levels were significantly lower following the ALA diet ( 13.20 ± 1.21 nM BCE ) , relative to the AAD ( 15.59 ± 1.21 nM BCE ) ( p < 0.05 ) . Mean NTx level following the LA diet was 13.80 ± 1.21 nM BCE . There was no change in levels of BSAP across the three diets . Concentrations of NTx were positively correlated with the pro-inflammatory cytokine TNFα for all three diets . The results indicate that plant sources of dietary n-3 PUFA may have a protective effect on bone metabolism via a decrease in bone resorption in the presence of consistent levels of bone formation
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 .