## 1 Introduction  
Honey is a product that is easily metabolized by humans. It provides many nutrients and energy, and has an advantageous influence on the gastrointestinal tract functions [1]. As a carrier of bioactive substances, honey is an important dietary component supporting the treatment of many diseases [2; 3]. This is associated, among others, with presence of bee enzymes and phenolic compounds in a honey [2; 4]. The phenolic content mainly depends on the geographical and botanical origin of a honey [5; 6; 7]. Phenolic compounds, especially flavonoids and phenolic acids supplied to the human body with a honey, play an important role in, e.g., contributing to a deactivation of free radicals. They also have antimicrobial, anti-inflammatory, and anticancer properties [3; 4; 8; 9]. The other bee products, including propolisis, pollen, bee bread, or even drone brood homogenate, are also a rich source of bioactive substances possessing antioxidant properties [10; 11; 12]. Honey and other bee products may represent an alternative to food additives, and may serve as a source of the biologically active ingredients of functional foods [13; 14]. Bee products, including propolisis and bee pollen, have been utilized to enrich a honey with substances that are antioxidant in character; however, their too-high content may not be acceptable from a sensory point of view [15; 16]. Bee pollen has also been used as an ingredient enriching cakes, fermented milk drinks, or cheeses, while propolisis has been added to meat products [13]. Bee bread is a preserved fermentation product being a mixture of flower nectar, pollen, and bee secretion with a wide range of bacteria and yeasts required for fermentation. It is stored in honeycomb cells [17; 18]. This product has strong antimicrobial, antioxidant,antiradical, anti-inflammatory, and anti-cancer activities [17; 18; 19]. Already in ancient times, bee bread was used for nutritional and therapeutic purposes in the many cultures. Today, bee bread is considered as a valuable dietary supplement or as a functional food ingredient, and interest in its use has been significantly increasing recently [17; 19]. In case of anaerobic conditions, the pollen, honey, and bee secretion mixture undergoes fermentation, during which hydrogen peroxide, organic acids, and antibacterial peptides are formed [18]. In addition, the content of basic nutrients changes significantly during this process [20]. Due to its low pH, bee bread is an excellent environment for development of lactic acid bacteria, including those from _Lactobacillus_ and _Bifidobacterium_ genera, participating in the fermentation process. Apart from bacteria, yeasts, especially those from the _Saccharomyces_genus, and _Aspergillus_ and _Penicillium_ holds also play a crucial role in the formation of this bee product [18]. Bee bread has a higher nutritional value and better digestibility when compared to bee pollen, as well as is characterized by a richer chemical composition [17; 19]. It contains more proteins, vitamins, minerals, amino acids, and lipids than bee pollen [17; 20; 21]. The process of transforming pollen into bee bread involves dissolving of pollen sheaths, so it is easier to digest than bee pollen itself. The presence of bee digestive enzymes and honey in a bee bread results in an increase in its nutritional value, while its higher content of carbohydrates and lactic acid prevents development of molds and spoilage bacteria [17; 18]. Bee bread contains numerous phenolic compounds, including nigerin, chrysin, kaempfer, and \(p\)-coumaric acid, and traces of both caffeic and ferulic acids as well as naringenin and quercetin [20; 21; 22; 23; 24]. Bee bread is also a valuable source of minerals, especially potassium [25]. The content of these compounds, especially phenolic compounds having antioxidant properties in particular, contributes to the high health-promoting value of bee bread [17; 21; 22; 23; 24].