Yogurt is obtained by using specific micro-organisms to ferment milk. The live cultures in yogurt contain lactobacillus and streptococcus sp. Yogurt cultures are known to have positive effects on your health, such as, for example, helping your digestive system work better.
Remember that the enzymes are alive from production to consumption and promote the absorption of lactose (milk sugars). These live enzymes are also what gives your yogurt its characteristic tanginess and aroma.