**9. Conclusion and future directions**

Food's major role is to provide sufficient nutritive substances, which will satisfy the need for food of the human organism. Today, nutrition science faces new challenges far beyond the

There are both socioeconomic changes taking place in the world and changes in the demo‐ graphic structure of population – growing number of elderly people and increase of the expenses for healthcare. Therefore, governments, researchers, health experts, and the foodstuff industry, in general, direct their efforts to identification and creation of functional foods, which may improve the health of the local population, reduce the risk of diseases with social impact, such as cardiovascular diseases, cancer, osteoporosis, and improve the quality of life for the people. In combination with healthy living, the daily use of these functional foods may have positive impact for the health of both working people in active age and their families and for the elderly. This will result in the sharp reduction of the expenses for healthcare and in the

Nowadays scientific evidences proved that some foods and food ingredients have favorable physiological and psychological effects beyond the supply with major food substances. Modern researches focus on the identification of the biologically active components in food, which maintain human health and reduce the risk of diseases. It has been found that many traditional foodstuffs, such as eggs, milk, whole-wheat food, fruits, vegetables, soya, etc. contain components of potential benefit for health. Apart from these foods, there are new products that have been developed to increase or combine these useful components because

Functional foods are foods that are consumed as part of the normal nutrition process. They have useful effects when consumed in normal quantities within the dietary regime. Functional

optimization of physical and mental health of the population.

**•** Food of natural origin – unskimmed milk, whole-wheat bread, etc.

**•** Food technologically or biotechnologically enriched with some ingredient

**•** Food, in which the nature of one or more substances has been modified

**•** Food, in which bioavailability of one or more substances has been modified

**•** Food, which is a combination of two or more of the foods described above

**•** Food from which ingredient has been extracted technologically or biotechnologically

Functional food may be addressed to the overall population or separate groups identified in terms of age (e.g., children or adults), genetic and enzyme modifications (intolerance toward gluten, lactose intolerance), functional status (pregnancy, for example), etc. Functional foods must be in conformity with the overall significance of nutrition – potential interrelations with other food substances and ingredients or possible undesired effects, including allergies and

The foundations of the modern science of functional foods were laid in Japan during the 1980. The concept of food of specific health use (FOSHU) was established in 1991. Foods defined as

of their benefits or desired physiological effects.

food could be:

intolerance.

concept of food insufficiency.

208 Immunopathology and Immunomodulation

Probiotics are reliable resources for prevention and treatment of immune disorders. There are a lot of encouraging data based on analyses of studies in humans and animal models that probiotics possess clinical efficacy in ulcerative colitis and irritable bowel syndrome as well as other intestinal diseases such as infectious diarrhea, antibiotic-associated diarrhea, necrotizing enterocolitis. The most recent studies suggest the exciting possibility that probiotics can be modified for delivery of vaccines and to potentiate the effects of vaccination [68]. While the paradigm of discovery-based genomics in probiotic LAB has uncovered vital aspects of probiotic mechanisms, it has also revealed the complexity of these interactions with the resident microbiota and the mucosal immune system. Nevertheless, a great opportunity was revealed by this challenge. For example, probiotic bacteria are now being explored as suitable models for vaccine/drug production, due to their close association with host immunity and immunomodulatory action [45, 69]. Latest discoveries show that the role of probiotic bacteria and the resident microbiota extend far beyond gastrointestinal health. It has revealed neuro‐ chemical importance of intestinal homeostasis. There are studies that show cross talk between gastrointestinal tract and brain (brain–gut axis) [70]. Along with these advancements, it is important that human clinical trials continue with experimental designs that are wellcontrolled and well-defined, reflecting the great progress that has been made in the field of probiotic and GIT microbiome research [71]. With more than a century passing since Metch‐ nikoff's observations, keen experimental design using integrated genomics has led to a clearer definition of probiotic bacteria, as well as a model for continued discovery. Bulgaria becomes famous in the world with *Lactobacillus bulgaricus* and the Bulgarian territory is still an important reservoir for isolation of natural strains of lactic acid bacteria, which after an additional selection are used as starter cultures for the production of various fermented foods and probiotic products. The biggest challenge for researchers in the field of nutrition, at present and in the future, is the study of the relationship between a certain food or a nutrient and improved health or reduced risk of various diseases. Provision of accessible and comprehen‐ sive information about the properties of functional foods is crucial for food selection by consumers.
