This meta- analysis concludes that l-arginine supplementation can significantly reduce blood TAG levels ; however , there is insufficient evidence to support its hypocholesterolaemic effects .
A number of clinical trials have examined the effect of l-arginine on lipid profile in recent years ; however , the results remain equivocal .
Therefore , the present study aims to summarise and quantitatively examine the available evidence on the effectiveness l-arginine supplementation on lipid parameters using a systematic review and meta-analytic approach .
Arginine supplementation modulates pig plasma lipids, but not hepatic fatty acids, depending on dietary protein level with or without leucine
Background In the present study , the effect of arginine and leucine supplementation , and dietary protein level , were investigated in commercial crossbred pigs to clarify their individual or combined impact on plasma metabolites , hepatic fatty acid composition and mRNA levels of lipid sensitive factors . The experiment was conducted on fifty-four entire male pigs ( Duroc × Pietrain × Large White × L and race crossbred ) from 59 to 92 kg of live weight . Each pig was r and omly assigned to one of six experimental treatments ( n = 9 ) . The treatments followed a 2 × 3 factorial arrangement , providing two levels of arginine supplementation ( 0 vs. 1 % ) and three levels of basal diet ( normal protein diet , NPD ; reduced protein diet , RPD ; reduced protein diet with 2 % of leucine , RPDL ) . Results Significant interactions between arginine supplementation and protein level were observed across plasma lipids . While dietary arginine  increased total lipids , total cholesterol , HDL-cholesterol , LDL-cholesterol , VLDL-cholesterol and triacylglycerols in NPD , the inverse effect was observed in RPD . Overall , dietary treatments had a minor impact on hepatic fatty acid composition . RPD increased 18:1c9 fatty acid while the combination of leucine and RPD reduced 18:0 fatty acid . Arginine supplementation increased the gene expression of FABP1 , which contributes for triacylglycerols synthesis without affecting hepatic fatty acids content . RPD , with or without leucine addition , upregulated the lipogenic gene CEBPA but downregulated the fat oxidation gene LPIN1 . Conclusions Arginine supplementation was responsible for a modulated effect on plasma lipids , which is dependent on dietary protein level . It consistently increased lipaemia in NPD , while reducing the correspondent metabolites in RPD . In contrast , arginine had no major impact , neither on hepatic fatty acids content nor on fatty acid composition . Likewise , leucine supplementation of RPD , regardless the presence of arginine , promoted no changes on total fatty acids in the liver . Ultimately , arginine , leucine and dietary protein reduction seem to be unrelated with fatty liver development
This meta- analysis concludes that l-arginine supplementation can significantly reduce blood TAG levels ; however , there is insufficient evidence to support its hypocholesterolaemic effects .
A number of clinical trials have examined the effect of l-arginine on lipid profile in recent years ; however , the results remain equivocal .
Therefore , the present study aims to summarise and quantitatively examine the available evidence on the effectiveness l-arginine supplementation on lipid parameters using a systematic review and meta-analytic approach .