Protective effects of proanthocyanidins at the intestinal levelagainst thermooxidative stress due to ingestion of sunflower oil used in frying

The repeated frying of food in sunflower oil produces thermo-oxidation and polymerization, potentially negative for health. The reaction of the gastrointestinal system to these compounds is unknown. Proanthocyanidins have antioxidant and lipid-lowering properties. We hypothesize that a carob-fruit extract rich in proanthocyanidins (CFE) improves the defense of the intestine against thermo-oxidative aggression. In sunflower oil, the thermo-oxidation produced by repeated frying of fish was studied while, in Wistar rats, the effect of jointly administering altered sunflower oil and CFE on: the digestion of thermo-oxidized compounds, postprandial lipaemia, proteins involved in lipid absorption, antioxidant and hemoxygenase-1 activity and expression in the small intestine. Twelve male Wistar rats, 200-250 g were cannulated for one week with the mixture of the thermo-oxidized oil-CFE or the thermo-oxidized oil. Thermo-oxidation was determined in sunflower oil and in the postprandial-fat of the gastrointestinal lumen, postprandial lipaemia, the proteins NPC1L1, ACAT-2 and MTP, and the antioxidant status in the duodenum, jejunum and ileum. High thermo-oxidation and polymerization levels were found on sunflower oil and fat in the gastrointestinal lumen. The administration of thermo-oxidized sunflower oil-CFE decreases the digestibility of the oil and the polymeric/thermo-oxidized compounds, reduces postprandial lipaemia, increases NPC1L1, ACAT-2, and MTP, and improves the intestinal antioxidant status and excretion of fecal polymers. The use of CFE reduces postprandial lipaemia and guarantees an adequate intestinal antioxidant status against thermo-oxidized lipids.