The intestinal microflora is carefully balanced. The human gut is home to around 400 different species of good and bad bugs. However, the good bugs have to share their environment with bad bugs such as Salmonella, E.Coli and Clostridium. The way to balance between good and bad bacteria is to maintain good digestive health, creating stable "microflora". It is generally recommended that probiotics are taken on a daily basis to create this balance.