Cytotoxic compounds generated in heated oil and assimilation of oil in Wistar rats.

We have previously suggested that gluten binds with decomposition products from thermally oxidized oil during frying, and that low-molecular-weight compounds bound to browned gluten damage the liver in rats. Ten-week-old male Wistar rats were fed for 11 weeks ad libitum a diet containing 7 wt% fresh frying oil and 0.1 wt% gluten heated in/without oil at 180 degrees C for 10 h. Feces collected weekly and serum were subjected to lipid and hematological analyses, respectively. Values obtained in the analyses did not differ from those of the control group. The results show that thermally processed gluten does not influence the digestion, absorption, metabolism, and growth of rats, regardless of the cytotoxic low-molecular-weight compounds, and that ingested fresh oil was assimilated normally. Together with the previous results, the odor of thermally processed gluten stimulated the rats' appetite, and completely assimilable fresh oil and cytotoxic low-molecular-weight compounds bound to gluten were ingested, and thus organ damage and rapid body weight increase were observed. As commercial deep-fried products are often made with repeatedly used oil with periodically added fresh oil, similar to the present experimental diet, obesity and organ damage may also occur in humans.