## 1 Introduction  
The increase in the incidence of chronic noncommunicable diseases, including atherosclerosis, high blood pressure and type 2 diabetes, which has been observed for many years, is mainly associated with obesity. The main cause of these diseases is an incorrect lifestyle, including an inappropriate diet. Numerous studies confirm that sugar, as a food ingredient, plays a role in the development of obesity and diabetes, and cardiovascular diseases [1, 2, 3, 4]. Therefore, a search is still going on for new substances with high sweetening power and low calorie content, which may be an alternative to sugar. Intense sweeteners allow for the sucrose elimination from food products. Most are synthetic compounds. For some time, researchers have been paying much attention to the _Stevia rebaudiana_ [PERSON]. The plant belongs to the _Asteraceae_ family and is native to Brazil and Paraguay. For centuries, \"sweet leaves\" were used by the indigenous tribes of Paraguay and Brazil to counter the bitter taste of various plant-based medicines and drinks. The Guarani Indians used them to sweeten and stimulate digestion, and applied as compresses for wounds and other skin ailments [5]. This plant attracted great interest of nutritionists due to compounds of strong sweetening properties present in its leaves as diterpene glycosides, rebaudioside, which is 250-300 times sweeter than sucrose. Studies have also shown that _S. rebaudiana_ is a good source of total carbohydrates (including dietary fiber), minerals and contains a number of secondary metabolites, such as pigments or phenolic compounds. The latter, with a role other than nutritional, are not considered essential for the body functioning. However, they may prevent diseases. Their systematic intake may have a beneficial effect on health protection and prevent or even treat diseases [6; 7; 8]. Essential oils, sesquiterpenes (\(\delta\)-caryophyllene, \(\delta\)-farmesene, humulene, candinene, nerolidol) and monoterenes (linalool, terpinen-4-ol, terpineol) are important phytochemicalal compounds of this plant. The leaves also have a significant amount of tannins and alkaloids, moderate contents of cardiac glycosides and saponins, and small amounts of anthraquinones. Moreover, the dry-leaf extract contains water-soluble xanthophylls and chlorophylls, and hydroxycinnamic acids (caffeic and chlorogenic acid) [9; 10; 11; 12; 13; 14]. Studies indicate that steviol glycosides derived from _S. rebaudiana_ leaves have, i.a., hypoglycemia [15; 16; 17; 18; 19; 20; 21], hypotensive [16; 18; 22; 23; 24; 25; 26], anti-inflammatory and immunomodulatory properties [16; 21; 27; 28; 29]. Steviol glycosides are widely used in many countries around the world, including Japan, Brazil, Australia, Switzerland, United States, Mexico and the European Union. In 2008, the United States Food and Drug Administration (US FDA) qualified steviol glycoside preparations as Generally Recognized as Safe (GRAS). In the same year, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) established the Acceptable Daily Intake (ADI) of steviol glycosides at 0-4 mg/kg body weight/day [30; 31]. In 2008, the European Union recognized _S. rebaudiana_ as the novel food, but now as a regular food product [32; 33]. In Germany in 2011, _S. rebaudiana_ was established as a traditional food [34; 35]. In order to ensure consumer safety, in 2011, the regulation concerning the using steviol glycosides (E 960) in food products was published. Steviol glycosides can be used as sweeteners in beverages, sweets, sweeteners, chewing gums, fruit and vegetable preserves, bakery products and fish preserves. E 960 sweeteners are not authorized as a food additive for infants, toddlers and children (under 3 years of age) [32]. In 2016, the EU gave detailed information and conditions for the using the name of steviol glycosides [32; 36].