[Recent research on the physiological effects of various types of compounds present in heated fats].

Combe, Constantin and Entressangles's work on the intestinal absorption of various new compounds formed during the heating of fats revealed that most of these compounds may pass through the intestinal mucosa, but that the absorption rate varies from a type of compound to another one. Among all the compounds present in the heated fats, the fraction of cyclic monomers was the most studied; previous works revealed that this fraction was toxic. However recent result of Iwaoka and Perkins seem to indicate that cyclic monomers are well tolerated by rats and induce only a slight effect on lipid metabolism; these surprising results may be due to the fact that the cyclic monomers are well tolerated by rats and induce only a slight effect on lipid metabolism; these surprising results may be due to the fact that the cyclic monomers used by Iwaoka and Perkins included only cyclohexadienic and aromatic compounds; Saito and Kaneda indeed obtained marked toxic effects with cyclic monomers including in particular compounds with cyclohexanic, cyclohexenic and cyclohexyl 1,2 diylidene structures; on the other hand, Potteau, Dubois and Rigaud identified after hydrogenation not only cyclohexanic compounds but also compounds with disubstituted cyclopentanic and hexahydroindane structure, in thermopolymerizated or thermally oxidized oils, which proved to be toxic to experimental animals, in particular in breeding experiments. Some experimental facts suggest a system of detoxification consisting in particular in the urinary glucuronide excretion. The apolar thermic polymers (cyclic or not) are little absorbed and produce few or no physiological effect; however they can be found again in appreciable amounts in adipose tissue (Billek and Rost) or in liver (Perkins and Taubold). Very little is known on the other fractions present in the heated fats, except that the fraction of oxidized acids can globally prove to be toxic. Alexander's work does not seem quite convincing to us: the statement according which oils rich in monoenic fatty acids would be more toxic after heating than the oils rich in polyunsaturated fatty acids is not based on reliable experimental results.