Probiotics as functional foods in enhancing gut immunity

Abstract

Probiotics as microbes when administered in sufficient amounts as functional food impose beneficial effects on gut microbiota and thus enhance health of host. The indigenous microflora of gastrointestinal tract acts as an anatomic barrier against antigens present in food, invading microorganisms which regulates the immunophysiologic mechanism. Many factors may lower the resistance of the body which may lead to inflammatory, infectious, neoplastic, and degenerative conditions. There are other means of treatment like using antibiotics, irradiation, and immunosuppressive therapy which may change normal composition of gut flora. A variety of functional properties of probiotics bound their consideration as conventional, medicinal foods, and dietary supplements. The most commonly used probiotics are of two genera, Lactobacillus and Bifidobacterium. Healthy microflora is the chief basis of probiotic therapy in literature. Probiotic bacteria demonstrate various immunomodulatory effects and therefore may be treated as novel tool to reduce inflammation in the intestine and dysfunction of gut mucosa, including acute gastroenteritis, inflammatory bowel disease, and food allergy, and downregulate hypersensitivity reactions. A large number of probiotic effects are explained by regulating immunity, especially the balance between anti-inflammatory and proinflammatory cytokines. Probiotics stabilize microbial environment of the gut and the intestinal permeability barrier. This leads to enhanced mucosal IgA responses which promote further the immunological barrier and responses of gut mucosa. In addition, providing immunomodulatory effect on gut mucosa, probiotic therapy is now also being used to cure infections in other organs such as respiratory tract, urogenital tract, and others. This chapter focuses on roles of probiotics as functional foods.