Öz
The human gastrointestinal tract (GIT) contains a rich, complex microbiota that plays an important role in digestion, immunology, and the occurrence of certain diseases. Under normal conditions, the composition of the gut microbiota is stable. However, the composition of the microbiota may change due to changes in diet, use of certain medications and stress. Today, it is a common and known method to take probiotics, which are defined as living microorganisms such as bacteria, yeast, when taken in sufficient quantities to regulate the intestinal microbiota, in the form of food or as a food supplement. In recent years, the use of paraprobiotics, which are non-living (inactive) microorganisms, or postbiotics, which are metabolic by-products released from living bacteria or after bacterial degradation, have started to attract attention as an alternative to probiotics. Paraprobiotics and postbiotics demonstrate many health effects such as regulating intestinal health and strengthening the immune system, just like probiotics, in the hosts where they are applied. In this study, studies on paraprobiotics and postbiotics that can be used instead of probiotics and provide similar health effects are reviewed.