Sunflower oil versus olive oil and iron metabolism in rats. Influence of afrying process

Olive oil and sunflower oil were used in repeated potato-frying operations without turnover until the oils reached the limit of 25% polar compounds al lowed by law. Over a 28 day period, five groups of rats were fed diets cont aining 8% unused olive oil, olive oil used in 48 and 69 potato frying opera tions, unused sunflower oil and sunflower oil used to fry potatoes 48 times . In the final week, faeces and urine were collected and, on day 28, animal s were sacrificed. The type of oil, unused or used in frying, did not modif y food intake, body weight, faecal iron and its apparent absorption or rete ntion, but consumption of oils used in frying tended to increase urinary ir on excretion. No differences were found in serum iron, total iron-binding c apacity and haemoglobin values. Iron contents and concentrations in liver, spleen and skin did not vary between groups. Iron concentrations in erythro cytes were significantly higher in rats fed sunflower oil, either unused or used in frying. It was concluded that the consumption of sunflower oil com pared to olive oil could affect intra- and extracellular haematic distribut ion of iron, probably associated with changes in membrane permeability, and that some alteration products of the oils originated during frying tend to increase urinary iron losses without repercussions on iron metabolism. (C) 2000 Society of Chemical Industry.