Many studies have shown that the nature of the lipid consumed in the diet significantly affects the prevalence of coronary, inflammatory or autoimmune diseases(Reference James, Gibson and Cleland^1, Reference Yaqoob²). The present study was conducted to compare the impact of feeding mice on diets enriched with edible oils (150 g/kg diet; fish oil (FO), olive oil (OVO) and orujo olive oil (ORO)) with that of a basal diet (BD) enriched with 20 g maize oil/kg on the ability to modulate oxidative reactive species and pro-inflammatory mediator generation by stimulated murine macrophages. Swiss male mice were fed on the different diets for 8 weeks. Diets were formulated according to American Institute of Nutrition (AIN) recommendations(Reference Bieri, Stoewsand, Briggs, Philips, Woodward and Knapka³). Peritoneal macrophages were isolated from these mice and stimulated. Reactive oxygen (O₂– and H₂O₂) and nitrogen (NO₂–) species, PGE₂, TNFα and IL-6 were measured in the supernatant fractions from 106 cells. All test diets down regulated NO generation compared with the BD (Fig.1); in contrast, FO increased H₂O₂ generation whereas OVO and ORO group diets significantly inhibited this ROS production compared with the BD. In addition, ORO was able to decrease O₂– formation compared with the BD group (Fig.1). Finally, both OVO and FO groups significantly decreased PGE₂ and cytokine production (Fig. 2). These results are in agreement with those of other authors in that a diet enriched in olive oil was found to show a protective effect against oxidative stress and inflammation(Reference Moreno, Carbonell, Sanchez, Miret and Mitjavila^4, Reference Perona, Arcemis, Ruiz-Gutierrez and Catala⁵)and they confirm the preventive anti-inflammatory properties of FO(Reference Calder⁶). Moreover, the results provide important additional data about the ability of ORO to prevent oxidative damage to cells.

Fig. 1. Reactive oxygen and nitrogen species generated by stimulated murine peritoneal macrophages isolated from mice fed on different oil-enriched diets. Values are means with their standard errors represented by vertical bars for five animals fed on each diet. Mean values were significantly different from those for BD (ANOVA and Student's t test): *P<0.05, **P<0.01, ***P<0.001.

Fig. 2. PGE₂ and cytokines generated by lipopolysaccharide-stimulated murine peritoneal macrophages isolated from mice fed on different oil-enriched diets. Values are means with their standard errors represented by vertical bars for five animals fed on each diet. Mean values were significantly different from those for BD (ANOVA and Student's t test): *P<0.05, **P<0.01, ***P<0.001.