Frying oils with high natural or added antioxidants content, which protect against postprandial oxidative stress, also protect against DNA oxidation damage.

PURPOSE: Using sunflower oil as frying oil increases postprandial oxidative stress, which is considered the main endogenous source of DNA oxidative damage. We aimed to test whether the protective effect of virgin olive oil and oil models with added antioxidants against postprandial oxidative stress may also protect against DNA oxidative damage. METHODS: Twenty obese people received four breakfasts following a randomized crossover design consisting of different oils [virgin olive oil (VOO), sunflower oil (SFO), and a mixed seed oil (SFO/canola oil) with added dimethylpolysiloxane (SOX) or natural antioxidants from olives (SOP)], which were subjected to 20 heating cycles. RESULTS: We observed the postprandial increase in the mRNA levels of p53, OGG1, POLB, and GADD45b after the intake of the breakfast prepared with SFO and SOX, and an increase in the expression of MDM2, APEX1, and XPC after the intake of the breakfast prepared with SFO, whereas no significant changes at the postprandial state were observed after the intake of the other breakfasts (all p values <0.05). We observed lower 8-OHdG postprandial levels after the intake of the breakfast prepared with VOO and SOP than after the intake of the breakfast prepared with SFO and SOX (all p values <0.05). CONCLUSIONS: Our results support the beneficial effect on DNA oxidation damage of virgin olive oil and the oil models with added antioxidants, as compared to the detrimental use of sunflower oil, which induces p53-dependent DNA repair pathway activation.

Effect of frying oils on the postprandial endoplasmic reticulum stress in obese people.

The addition of antioxidants to frying oil reduces postprandial oxidative stress and the inflammatory response. ER stress may trigger both inflammation and oxidative stress processes. We aimed to determine the biological effects of the intake of four models of frying oils on postprandial ER stress in peripheral blood mononuclear cells. Twenty obese people received four breakfasts following a randomized crossover design, consisting of muffins made with different oils (virgin olive oil (VOO), sunflower oil (SFO), and a mixture of seed oils (SFO/canola oil) with either dimethylpolysiloxane (SOD) or natural antioxidants from olives (SOP) added), which were previously subjected to 20 heating cycles. ER stress was assessed by measuring the mRNA levels of sXBP1, BiP, CRT, and CNX in peripheral blood mononuclear cells. Our study showed that the intake of the muffins made with SFO induced the postprandial increase of the mRNA levels of the ER stress-sensor sXBP1, and the ER stress related chaperones BiP and CRT (all p-values <0.05). The harmful effects associated with the use of SFO as frying oil, in terms of inflammatory response and postprandial oxidative stress, may be partially mediated by the induction of postprandial ER stress.

Olive oil phenolic compounds decrease the postprandial inflammatory response by reducing postprandial plasma lipopolysaccharide levels.

We investigated the molecular mechanisms by which phenolic compounds (phenols) in virgin olive oil reduce the postprandial inflammatory response with the aim of identifying the transcription factor involved and the downstream effects. Olive oil-based breakfasts prepared with virgin olive oil (VOO) with high (398 ppm), intermediate (149 ppm) and low (70 ppm) phenol content were administered to 49 metabolic syndrome patients following a randomized crossover design. The consumption of a high-phenol VOO-based breakfast limited the increase of lipopolysaccharide plasma levels, TLR4, and SOCS3 proteins (p<0.001, p=0.041 and p=0.008, respectively), the activation of NF-κB (p=0.016) and the IL6 (p=0.007 and p=0.048, low and intermediate oil, respectively), IL1B (p=0.002, intermediate oil), and CXCL1 (p=0.001) postprandial gene expression, in peripheral blood mononuclear cells, as compared with the consumption of a breakfast prepared with the same oil but with low or intermediate phenol content. Virgin olive oil phenolic compounds reduce the postprandial inflammatory response in association with postprandial plasma lipopolysaccharide levels.