What are Probiotics?
Probiotics are live microorganisms that are similar to beneficial microorganisms found in the human digestive tract. They are also called “friendly bacteria” or “good bacteria.” When administered in adequate amounts, a probiotic may offer several health benefits. Certain yeasts may also be helpful.

Saccharomyces boulardi (yeast)
You don’t necessarily need probiotics to be healthy. However, they may help with digestion and also offer protection from harmful bacteria, just as the existing “good” bacteria in your body already do.
You can add probiotics to your diet through nutritional supplements or foods such as yogurt, fermented and unfermented milk, miso, and some juices and soy drinks. Read product labels carefully, looking for a statement that the product “contains live and active cultures,” such as lactobacillus. Products that say “made with live cultures” have often been cooked (via pasteurization) and may actually have no live cultures.
Uses for Health Purposes
The world is full of microorganisms (including bacteria), and so are people’s bodies: the skin, the gut, and most other orifices are swarming with microorganisms. Friendly bacteria are vital for proper development of the immune system. They protect against microorganisms that cause disease and aid in the digestion and absorption of food and nutrients. Each person’s mix of bacteria varies. Interactions between a person and the microorganisms in their body, and among the microorganisms themselves, can be crucial to your health and well-being.
Antibiotics can kill friendly bacteria in the digestive tract along with unfriendly bacteria. Probiotics may offset side effects from antibiotics like gas, cramping, or diarrhea. There is no brand of probiotic supplement shown to be most effective. Generally, taking two or three standard probiotic pills per day may help prevent or alleviate stomach upset, thrush (infection of the mucus membrane lining the mouth and tongue), yeast infections, and diarrhea that can occur with antibiotic use.

Lactobacillus acidophilus (bacteria)
Side Effects and Risks of Probiotics
Some live microorganisms have a long history of use as probiotics without causing illness in people, but probiotic safety has not been subject to thorough medical or scientific study. It is unclear how safe they are for young children, elderly people, and people with compromised immune systems. Tell your doctor about any side effects from probiotics or antibiotics.