Epidemiological evidence suggests that diets enriched in soy protein have beneficial health effects. Previous studies in our laboratory have shown that dietary soy isoflavones enhance antioxidant gene expression mediated by MAPK/NFkB signalling pathways.

Aim: 

To study possible beneficial metabolic effects of soy rich diet and to correlate them with the antioxidant effect previously shown.

Methods: 

We used 3 month-old OF1 male mice fed with a soy rich diet or a low soy diet. We studied metabolic profiles by nuclear magnetic resonance (NMR) in blood plasma and hepatic mitochondrial H₂O₂ production by fluorimetric assays. We used MATLAB for all data multivariate and peak-fitting analysis.

Results: 

Confirming earlier results, hepatic mitochondria from mice fed soy rich diet had significant lower production of H₂O₂ compared to mice fed low soy diet. These results were accompanied by metabolic changes in blood plasma. The multivariate analysis showed clear separation between groups and allowed identification of relevant metabolites. Metabolic differences between groups were moderate but consistent. Significant differences included a decrease in lipids (LDL, VLDL and PUFAs). Other metabolic differences included glucose, ketone bodies, glycoproteins, phospholipids and aminoacids. Correlation between these metabolites and peroxides levels is currently under investigation.

Conclusions: 

Our results show that beneficial metabolism effects induced by soy rich diet are moderate but extensive. We observe antioxidant effect and favorable lipid profile alterations as previously reported. Other metabolites affected indicate effects in glucose consumption, ketone bodies metabolism and energy production from protein.

This work has been supported by BFU2007-65803/BFI and ISCIII2006-RED13-027 from the 'Red Temática de investigación cooperativa en envejecimiento y fragilidad' (RETICEF RD06/003–027) to J.V., by grant GV/2007/263 to C.B and by grants GVPRE/2008/138 and Catholic University 2008-011-002 to J. G.