Abstract
Background: Lactic acid bacteria (LAB) have been attracting attention of food microbiologists for more than a hundred years. An attention of researchers and society is paid to their ability to influent human health, to preserve foods and to extend their shelf life. Currently, LAB group includes a large number of different bacterial genera: Lactobacillus, Lactococcus, Streptococcus, Pediococcus, Leuconostoc, Enterococcus, Oenococcus, Aerococcus, Carnobacterium, Vagococcus, Weisella and Tetragenococcus.
Some LAB species can provide a positive effect on consumer’s health due to changes in milk composition leading to a better digestibility of some milk components. Positive effect of LAB is also linked with restoring the intestinal balance in favour of beneficial microorganisms. These LAB strains are known as probiotics.
Probiotics, which are used in foods and nutrition supplements frequently, are isolated especially from gastrointestinal tract of humans and mammals, the vaginas of healthy women, breast and cow milk or fruits and vegetables.
Every strain included in the list of probiotic bacteria must necessarily have a proven positive effect on human health. Other important features of probiotics are that they must be precisely identified and classified, cannot be pathogenic, must be able to survive in the digestive tract and must be stable during food processing.
The effect of probiotic bacteria on the host health is based on their direct antagonism to pathogens and potential pathogens, as well as on the indirect expulsion of harmful microorganisms from the host. The adherence to the binding sites of mucous membranes, translocation blocking, competing for nutrients, the production of antimicrobial metabolites and the stimulation of the host immune system are applied here.
The usage of probiotics for direct treatment of any disease is rare. Usually they are applied as an adjuvant therapy, as an eliminator/reducer of medication side effects, for the prevention of diseases and for long-term support of host immunity. Disorders treated by probiotic bacteria include lactose intolerance, diarrhoea and constipation, infections, obesity and diabetes mellitus, allergic and autoimmune diseases, respiration disorders, oncologic diseases, neurological and psychological disorders.
On the other hand, some trials found out that probiotics had no effect on gut bacteria compared to inactive placebo.
Conclusion: There is a growing interest in probiotics and defining the proper use of these agents. Although probiotics seemed to have beneficial effects in many clinical trials, the efficiency of probiotics is strain and dose-dependent. Also, there are numerous clinical and methodological differences between trials (e.g., strain used, dose, administration) that make it difficult to draw a conclusion about the efficacy. Additional research in the form of well designed, randomized, doubleblind, placebo-controlled trials is needed. Although probiotics appear to be safe in general, caution should be used when administered to specific subgroups of patients such as the immunocompromised, the elderly, and children.
Keywords: Clinical application, disease treatment, mechanism, nutrition, origin, probiotics.
Graphical Abstract
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