Probiotics are living microorganisms that, when ingested, provide numerous health benefits. They're usually bacteria, but certain types of yeasts can also function as probiotics.You can get probiotics from supplements, as well as from foods prepared by bacterial fermentation. Probiotic foods include yogurt, kefir, sauerkraut, tempeh, and kimchi. Probiotics should not be confused with prebiotics, which are dietary fibers that help feed the friendly bacteria already in your gut. Dozens of different probiotic bacteria offer health benefits.The most common groups include Lactobacillus and Bifidobacterium. Each group comprises different species, and each species has many strains.Interestingly, different probiotics address different health conditions. Therefore, choosing the right type or type of probiotic is essential.Some supplements are known as broad-spectrum probiotics or multi-probiotics combine different species in the same product.Although the evidence is promising, more research is needed on the health benefits of probiotics.Importance of Microorganisms for Your GutThe complex community of microorganisms in your gut is called the gut flora or microbiota. Your gut contains hundreds of different types of microorganisms as many as 1,000, according to some estimations.This includes bacteria, yeasts, and viruses with bacteria making up the vast majority.Most of the gut flora is found in your colon, or large intestine, which is the last part of your digestive tract.Surprisingly, the metabolic activities of your gut flora resemble those of an organ. For this reason, some scientists refer to the gut flora as the "forgotten organ".Your gut flora performs many functions that are important for health. It manufactures vitamins, including vitamin K and some of the B vitamins.It also turns fibers into short-chain fats like butyrate, propionate, and acetate, which feed your gut wall and perform many metabolic functions.These fats also stimulate your immune system and strengthen your gut wall. This can help prevent unwanted substances from entering your body and provoking an immune response. However, not all organisms in your gut are friendly.Your gut flora is highly sensitive to your diet, and studies show that an unbalanced gut flora is linked to numerous diseases.These diseases include obesity, type 2 diabetes, metabolic syndrome, heart disease, colorectal cancer, Alzheimer's and depression. Probiotics and prebiotic fibers can help correct this balance, ensuring that your "forgotten organ" is functioning optimally.Impact on Digestive HealthProbiotics are widely researched for their effects on digestive health. Strong evidence suggests that probiotic supplements can help cure antibiotic-associated diarrhea.When people take antibiotics, especially for long periods of time, they often experience diarrhea even long after the infection has been eradicated.This is because the antibiotics kill many of the natural bacteria in your gut, which shifts gut balance and allows harmful bacteria to thrive.Probiotics also combat irritable bowel syndrome (IBS), a common digestive disorder, reducing gas, bloating, constipation, diarrhea and other symptoms.Some studies also note benefits against inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis.What's more, probiotics may fight Helicobacter pylori infections, which are one of the main drivers of ulcers and stomach cancer.