Also known as: Lactobacillus acidophilus, L. acidophilus, Bifidobacterium bifidus, lactic acid bacteria.
Potential uses: Probiotics are live microorganisms — usually bacteria — that are similar to the "good bacteria" found in the intestine. People use probiotics to treat and prevent conditions such as lactose intolerance, diarrhea, irritable bowel syndrome, and other gastrointestinal problems, as well as to strengthen their immune systems against infection. The theory is that introducing helpful bacteria into the intestinal tract improves the body’s immune defenses.
Usual dose: Probiotics are found in foods such as yogurt, fermented and unfermented milk, miso, tempeh, and some juices and soy beverages. They also can be taken in the form of dietary supplements, such as capsules, tablets, or powders. Doses can vary, but supplements generally contain anywhere from 1 to 10 billion bacteria.
Are there any risks? Probiotics can cause side effects such as gas and bloating, but these tend to be mild. However, people with weakened immune systems — such as those who are taking chemotherapy for cancer — could be vulnerable to infection by the bacteria. It is generally recommended that these people avoid probiotics.
What does the research show? According to the National Center for Complementary and Alternative Medicine, there is evidence that probiotics are helpful in preventing and/or treating diarrhea and other intestinal problems, urinary and vaginal infections, and eczema in children. Lab and animal studies suggest that probiotics may slow the growth of breast cancer cells. However, studies involving people are needed before we can really know whether probiotics have a role in preventing or treating breast cancer and other forms of cancer.