Probiotics are often called good or helpful bacteria because they help keep your gut healthy. Probiotics are naturally found in your body. You can also find them in some foods and supplements.actobacillus. This may be the most common probiotic. It’s the one you’ll find in yogurt and other fermented foods. Different strains can help with diarrhea and may help with people who can’t digest lactose, the sugar in milk. Bifidobacterium. You can also find it in some dairy products.