Probiotics are the beneficial bacteria that compete with harmful ones. However, this equilibrium between beneficial and harmful is a delicate balance. Many of our 21st century habits are disrupting influences wreaking havoc on our friendly bacteria. A junk food; diet, pharmaceutical drugs such as antibiotics, steroids, birth control pills; environmental chemicals; and psychological or mental stress all impact our gut flora. Specific beneficial strains can be killed or crowded out, allowing their neighborhoods to be overtaken by harmful bacteria or yeast, such as Candida Albicans.