The human gastrointestinal tract is colonized by a complex ecosystem of microorganisms, including beneficial intestinal bacteria that play crucial roles in maintaining health. Probiotics, prebiotics, and synbiotics are introduced into the diet to modify the intestinal microbiota, aiming to achieve, restore, and maintain a favorable balance. Probiotics are live microorganisms that confer health benefits to the host when administered in adequate amounts. Prebiotics are non-digestible food components that selectively stimulate the growth and activity of beneficial microorganisms in the gut. Synbiotics combine probiotics and prebiotics to enhance the survival and activity of probiotic microorganisms. The mechanisms of action of these substances include antagonism, competition for nutrients, immunomodulation, and inhibition of bacterial toxin production. Probiotics can prevent infections, modulate the immune system, and improve digestion processes. Prebiotics promote the growth of beneficial bacteria, enhance nutrient absorption, and reduce the risk of colorectal cancer. Synbiotics provide synergistic effects, improving the viability of probiotic microorganisms and providing specific health benefits. Clinical studies have demonstrated the positive effects of probiotics on gastrointestinal and allergic diseases, obesity, insulin resistance, and non-alcoholic fatty liver disease. Prebiotics have been shown to reduce the risk of colorectal cancer and improve immune function. Synbiotics have been effective in preventing osteoporosis, reducing blood fat and sugar levels, and treating brain disorders associated with abnormal hepatic function. The selection of probiotic strains, prebiotics, and synbiotics is crucial for their therapeutic effects. Further research is needed to identify new probiotic strains, optimize dosages, and evaluate safety and efficacy in clinical trials.The human gastrointestinal tract is colonized by a complex ecosystem of microorganisms, including beneficial intestinal bacteria that play crucial roles in maintaining health. Probiotics, prebiotics, and synbiotics are introduced into the diet to modify the intestinal microbiota, aiming to achieve, restore, and maintain a favorable balance. Probiotics are live microorganisms that confer health benefits to the host when administered in adequate amounts. Prebiotics are non-digestible food components that selectively stimulate the growth and activity of beneficial microorganisms in the gut. Synbiotics combine probiotics and prebiotics to enhance the survival and activity of probiotic microorganisms. The mechanisms of action of these substances include antagonism, competition for nutrients, immunomodulation, and inhibition of bacterial toxin production. Probiotics can prevent infections, modulate the immune system, and improve digestion processes. Prebiotics promote the growth of beneficial bacteria, enhance nutrient absorption, and reduce the risk of colorectal cancer. Synbiotics provide synergistic effects, improving the viability of probiotic microorganisms and providing specific health benefits. Clinical studies have demonstrated the positive effects of probiotics on gastrointestinal and allergic diseases, obesity, insulin resistance, and non-alcoholic fatty liver disease. Prebiotics have been shown to reduce the risk of colorectal cancer and improve immune function. Synbiotics have been effective in preventing osteoporosis, reducing blood fat and sugar levels, and treating brain disorders associated with abnormal hepatic function. The selection of probiotic strains, prebiotics, and synbiotics is crucial for their therapeutic effects. Further research is needed to identify new probiotic strains, optimize dosages, and evaluate safety and efficacy in clinical trials.