## 1 Introduction  
Fatty acids are crucial in the growth and development of the human body. They are structural components of lipids, which compose membranes of the cells and play an important role in processes like gene expression and cellular communication [1]. Fatty acids are classified into saturated and unsaturated carboxylic acids; their carbon chain can vary from 2 to 36 carbon atoms [2]. Omega-3 and omega-6 are polyunsaturated fatty acids (PUFAs) and they are essential for humans; they cannot be synthesized in our gastrointestinal tract, they must be consumed with food. Anthropological studies indicate that human beings evolved on a diet containing about 1:1 to 1:4 ratio of omega-3 and omega-6 fatty acids, yet over the past century there has been a significant increase of omega-6 intake due to increased consumption of vegetable oils (soybean, sunflower seeds, cottonseed, corn, and safflower seeds), resulting in omega-3 and omega-6 ratio of 1:15-20. According to multiple studies, excessive intake of omega-6 promotes blood clotting and platelet aggregation. Meanwhile, omega-3 fatty acids can reduce inflammation, which is usually at the base of many chronic diseases; moreover, it can reduce inflammatory effects associated with excessive intake of omega-6. Omega-3 has hypolipidemic, antithrombotic, vasodilatory, and antiarrhythmic effects. The most important for human health omega-3 acids are \(\alpha\)-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoicenoic acid (DHA) [3; 4; 5]. Deficiency of omega-3 consequently is a deficiency of DHA, which is a long-chain form of omega-3. Deficiency of DHA combined with incorrect omega-3 and omega-6 ratio leads to cognitive disorders and often to mental diseases [6]. In order to obtain the right amount of omega-3, daily diet can be replenished with food supplements or with functional food. There are studies proving that fatty acids present in pollen enhance the cognitive function of bees and bumblebees, but limited information about fatty acids in bee products [7; 8]. There are also studies, proving the presence of polyunsaturated fatty acids (PUFAs) in pollen [3; 6]. Our aim is to determine the composition of fatty acids in bee products such as bee pollen, bee bread, honey, and propolisis. Such study gives possibility to estimate whether pollen, composing bee products, collected from non-specific plants and in different areas vary significantly in composition of fatty acids. The selecting the analytical methodology to determine the fatty acids strongly depends on its nature. There are several methods and techniques described for the analysis of fatty acids in bee products. The extraction technique mainly depends on the analytical method that is used during the research. Usually lipids are extracted by different organic solvents and mixtures of it (petroleum ether, methanol, and chloroform), Soxhet, supercritical fluid extraction, and derivatization. Moreover, while using the supercritical fluid extraction, the fatty acids determination is performed by liquid chromatography. The total fatty acids content has mostly been determined by Soxhtlet extraction followed by gravimetry, while quantification has always been performed spectrophotometrically. Gas chromatography (GC) is the technique of choice when establishing fatty acids following extraction with organic solvents and conversion to the corresponding derivatives [9]. Many different methylation methods are described in literature, and four of them are commonly used: acid or base-catalyzed methylation, borontrifluoride methylation, methylation with diazomethane, and silylation [10]. GC/MS is the most widely used technique for determining the fatty acids profiles, due to its sensitivity and efficacy [10]. GC analysis was performed in order to evaluate and compare the composition of fatty acids in different bee products. Preparation of samples for analysis by GC involves lipid extraction and methylation procedures.