CONICET | Buscador de Institutos y Recursos Humanos

The intestinal microenviroment is a complex network of interactions among the microorganisms of the resident flora, epithelial and immune cells associated with the gut and nutrients. The gut associated lymphoid tissue (GALT) must distinguish antigens contained in food from commensal as pathogenic microorganisms. On the other hand, the diverse functionality of the microflora and its metabolic activities confers the GALT an important role in the modulation of the immune function, the metabolism of carcinogenic compounds and in providing an effective barrier against pathogenic bacteria. In this complex ecosystem, the important matter is to understand the mechanisms by which the GALT distinguish among the vast number of antigens it is exposed to, including microorganisms from the diet, to maintain the homeostasis. Some bacteria species (principally belonging to the genera Lactobacillus and Bifidobacterium) contained in fermented foods are regarded as probiotics, which can be defined as live microbial food ingredients that exert health benefits on the host. One of the most relevant properties of probiotics is the ability to stimulate the systemic and mucosal immune system. In this sense, many lactic acid bacteria (LAB) present in many fermented food as starter cultures are considered probiotics and they are deeply involved in the immunomodulation of the GALT. LAB have an adjuvant effect by the enhancement of the IgA production, the prevention of some intestinal infections, the modulation of the inflammatory immune response and the reduction of the levels of some tumour promoting factors. The influence of LAB, yoghurt or other fermented milks on the GALT functioning, selection criteria of LAB by their immunomodulating capacities and their role in the prevention of some intestinal bacterial infections and colon cancer will be extensively discussed in this review.

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