Fats are a basic, highly energetic component of food. Generally, it is believed that a high consumption level of fats alongside the improper composition of fats in a diet may cause risks of many typical civilization diseases such as: obesity, functional disorders of cardiovascular system, colorectal carcinoma, mammary cancer//breast carcinoma, as well as decreased power of the immune system. The composition of fatty acids in a daily diet is of special importance, in particular the rate between the saturated and single- and poly-unsaturated fatty acids. Lipids are also an important structural constituent of cell membrane (phospholipids, cholesterol). The n-3 and n-6 m poly-unsaturated fatty acids (EFA) are impossible to be manufactured (synthetized), thus, they must be supplied in a diet. The two basic EFAs are: an α-linolenic acid (C18:3) from the n-3 family, a precursor to eicosapentaenoic acid (EPA) and to docosahexaenoic acid (DHA), and a linoleic acid (C18:2) from the n-6 family, a precursor to arachidonic acid (AA). Cell membranes of the central neural system and of the retina function properly owing to a double layer of phospholipid molecules, and this layer consists mainly of EFAs. Therefore, human organisms must be supplied with EFAs, especially with EFAs that are not synthetised endogenicly, as they determine both the mental development of children and the proper functioning of the organisms of adults. Recently, there is a growing interest in trans- and cis-isomers of fatty acids, and in their conjugated forms (CLA). It is also attempted to explain mechanisms of their action at the molecular and genetic level, and to determine their role in stimulating the health condition of people. Experiments and research on animals (in particular with rodents) proved that CLA, especially the trans-10 & cis-12 isomers, could reduce or prevent fat deposition, improve the insulin response, inhibit the growth of cancerous cells, and reduce inflammatory processes. It is indispensable to conduct further investigation, especially for the purpose of checking the usefulness of CLA as a nutraceutic in preventing and treating contemporary civilization diseases.