Eating food is a basic human physiological need necessary for survival. The microbiome inhabiting the human digestive tract includes bacteria, and some of them referred to as probiotic have a positive effect on human health. Some of their beneficial properties can be attributed to the characteristic metabolites of the microbiome, called  postbiotics – a component of the cell walls of specific probiotic strains or lysates released as a result of the  breakdown of bacterial cells. The manner and effects of postbiotics on human health have not yet been fully  understood. Nevertheless, there are more and more studies that indicate their action to reduce inflammation and  oxidative stress, eliminate the presence of harmful pathogens and stimulate the human immune system. In  addition postbiotics can be used in food technology as preservatives, texture enhancers or functional additives.  The undoubted advantage of using postbiotics is their safety, ease of dosing and stability during storage. In this  paper definitions of postbiotics, their functions and characteristics of postbiotic substances as food ingredients and their impact on body functions were discussed. Based on an in-depth analysis of the literature on the subject,  it should be noted that despite the many promising data, it seems that further research is needed to identify and  understand the mechanisms of action of postbiotics and to optimize their effectiveness. First of all, confirmation of  the effectiveness of postbiotics in the action of improving human health requires confirmation.