Conjugated linoleic acid is an integral term for the mixture of positional and geometrical isomers of the octadecadienoic acids, whose two double-bonds are separated with one single-bond. The most common isomers are cis-9, trans-11, and trans-10, cis-12. Conjugated linoleic acid is present in the food namely in the red meat and dairy products which the contemporary dietary recommendations tend to limit. Those limitations should be compensated with dietary supplements. Experimental studies have shown the positive effects of the conjugated linoleic acid in the regulation of the body weight, in the reduction of risk factors of cardiovascular diseases, for improvement of immunity and in the reduction of risks of the development of some carcinomas. Those studies have also considered different effects of individual isomers. Stimulating results of experimental studies represent the basis of the research in human medicine, where the results are not so unequivocal. Studies are difficult to compare owing to the different arrangement (number of persons, daily dose, length of administration). Positive effects on the adiposity and proportion of the visceral fat was observed after the long-term administration, however, mechanism of the effect has not been explained yet. It can be due to the inhibition of lipoprotein lipase, rise of carnitine- palmitoyl transferase activity, induction of adipocyte apoptosis, modulation of PPARγ effects. For the explanation some new long-term studies with defined clinics will be necessary. Present view on the indication of the conjugated linoleic acid administration from the point of complex modulation of risks of the development of cardiovascular and metabolic diseases is inconsistent.

        Key words: conjugated linoleic acid, cardiovascular diseases, metabolic syndrome, plasma lipids, oxidative stress.