[Physiological effects, mechanisms of action and application of lactulose].

The discovery of lactulose as a bifidogenic factor became the background for the appearance of the prebiotics concept. Currently, lactulose is the most studied in terms of medical use oligosaccharide with a high prebiotic index. The exact mechanisms of action of lactulose remain largely unknown despite a number of new researches based on modern methods of molecular biology, genetics, and bioinformatics. The aim of this review to summarize and analyze the actual information about biological activity, probable mechanisms of action, and possible uses of lactulose in human nutrition. Results. The structure of lactulose, methods for its determination and preparation are briefly described. Promising methods for producing lactulose include enzymatic synthesis from lactose using ß-galactosidase or epimerase. Information on the physiological effects of lactulose and the mechanisms of its action on the human organism is presented. The works confirming the ability of lactulose to stimulate the growth of bifidobacteria and to influence the metabolism of the intestinal microbiota are summarized. The results of studies of the ability of lactulose to have antitoxic and anticarcinogenic effects are presented. The mechanisms of the positive effect of the prebiotic on the absorption of minerals, increased absorption of Ca and Mg in the human organism are described. The effect of lactulose on immunity and the possibility of its use to reduce the glucose blood level in patients with type 2 diabetes mellitus are shown. The main directions of the use of lactulose in food production are systematized. The data confirming the possibility of using lactulose as a growth factor for probiotics, as well as a protective agent to increase the survival of some starter cultures, are presented. Brief information on the doses and forms of lactulose apply in medicine is presented. The dependence of the effects of lactulose on the dose, health condition and age of patients has been established. Conclusion. Perspective directions of lactulose using in combination with probiotics, other prebiotics, and as an encapsulating ingredient for vitamins and other functional nutrition ingredients are determined. In this regard, the study of lactulose interaction with the components of complex products is relevant.

[Prebiotics as functional food ingredients: terminology, choice and comparative evaluation criteria, classification].

The purpose of this review is to analyze current concepts of prebiotics as one of the most promising groups of functional food ingredients, identify problems and trends in the investigations in this area. The background for the emergence and development stages of the concept of «prebiotics¼ as non-digestible food substances that selectively stimulate the growth and (or) the biological activity of one or a limited number of representatives of the protective microflora of the human intestine, contributing to the maintenance of its normal structure and biological activity is shown. The criteria for selecting prebiotics and the formula for prebiotic index determining are presented. Methods for determining the bifidogenic properties of functional foods enriched with probiotic microorganisms or prebiotic substances are described. Prebiotics are classified according to several factors: nature and structure, origin and sources of raw materials, the method of production, the field of application. It is shown that most researchers consider prebiotics only as substances of carbohydrate nature, primarily indigestible oligosaccharides. A brief description of the most studied prebiotics (fructans, galactans and lactulose) is given. The information on technological properties of oligosaccharide-prebiotics is generalized. It is shown that prebiotics belong to the fast growing segments in the world market of functional ingredients, however their production and use in Russia is still at the initial stage of development. The main tasks in the field of prebiotics researches are defined: clarifying the definition, improving the methods for analyzing their chemical composition, study of the effectiveness and mechanisms of influence on the intestinal microbiota, especially on the interaction in the «macroorganism-microbiota¼ system using modern molecular genetic methods; scientific substantiation of the possibility of prebiotics using for the prevention and treatment of alimentary-dependent diseases. For the practical implementation of these tasks, it is necessary to develop new cost-effective methods for the production of prebiotics and synbiotics, as well as food technology with their use.