The Food and Agriculture Organization of the United Nations defines probiotics as "live microorganisms administered in adequate amounts which confer a beneficial health effect on the host", probiotics have been called the "good bacteria". They can be used as complementary and alternative drugs rather than antibiotics. Probiotics are live microorganisms that can be found in dietary supplements and some foods. Probiotics can be found in the form of capsules or tablets, but can also be found in certain foods such as yogurt, soy beverages, fermented and unfirmed milk, and some juices. Most probiotics are bacteria that are similar to what is naturally found in people's guts; especially breastfed infants who have natural protection against many diseases.
The bacteria found in our gut are not actually in our stomach, it can be found in our lower small intestine and colon. The microbes in the large intestine complete the digestion process on any food components that were not digested in the small intestine such as lactose for people who are lactose intolerant, or fibers that are resistant to the enzymes in the small intestine. Some of these microbes actually produce vitamins. Lactobacilli and bifidobacteria are found in the intestines and keep them healthy; they produce lactic and acetic acids making it impossible for harmful bacteria to survive. The gastrointestinal tract is a bridge between "inside the body" and outside the body ", microbes passing through the GI tract interact with components of the immune system; this interaction can stimulate the immune system for optimal functioning.
People are interested in probiotics because these "good bacteria" are vital to developing the immune system to protect against microorganisms that cause disease, and they assist in the digestion and absorption of food and nutrients. Everyone's bacteria are different and the way the bacteria can interact in someone's body is crucial to support good health. The benefits of the "good bacteria" can be affected by antibiotics and disease-causing bacteria. Probiotics can be used to help with some side effects from antibiotics. Antibiotics are used for many different reasons, but along with killing the "bad bacteria" it can also kill the "good bacteria", when this happens it can affect the gut because that's where the "good bacteria" is. Many times probiotics are taken with the antibiotics to lower the chances or help with symptoms such as gas, diarrhea, and cramping. Disease-causing bacterium such as yeast, fungi, and parasites can destroy "good bacteria". Probiotics can help suppress some disease-causing bacteria that cause such things as irritable bowel syndrome, tooth decay, vaginal infections, skin infections, and stomach and respiratory infections that children can get from daycares.
Some live microorganisms have a long history of use as probiotics without causing illness to people. Probiotics have not been studied enough to know if they are safe for young people, elderly people, or people with compromised immune systems. Probiotics' side effects, if any occur, tend to be mild, such as gas and bloating. If you are thinking about taking probiotics, make sure to talk to your physician first.