Probiotics are beneficial bacteria (sometimes referred to as "friendly germs") that help to maintain the health of the intestinal tract and aid in digestion. They also help keep potentially harmful organisms in the gut (harmful bacteria and yeasts) under control. Most probiotics come from food sources, especially cultured milk products. Probiotics can be consumed as capsules, tablets, beverages, powders, yogurts and other foods. Pro biotics should not be confused with pre biotics. Prebiotics are complex sugars (such as lactulose, lactitol, a variety of fructo-oligosaccharides and inulin) that are used as fuel by the healthful bacteria to stimulate their growth and activity while suppressing the growth and activity of harmful organisms. Other foods that support probiotic activity include Japanese miso, tempeh, kefir, raw milk, kombucha, bananas, garlic and onions. When prebiotics and probiotics are combined in one product, it is called a syn biotic. Probiotics work by colonizing the small intestine and crowding out disease-causing organisms, thereby restoring proper balance to the intestinal flora. They compete with harmful organisms for nutrients and may also produce substances that inhibit growth of harmful organisms in the gut. Probiotic bacteria have been found to stimulate the body's immune system. They may also aid in several gastrointestinal illnesses such as inflammatory bowel diseases, antibiotic-related diarrhea, Clostridium difficile toxin-induced colitis, infectious diarrhea, hepatic encephalopathy, irritable bowel syndrome and allergy. Probiotics have been found to enhance the digestion and absorption of proteins, fats, calcium and phosphorus. They may help overcome lactose intolerance. Finally they may help restore healthful bacteria after a course of antibiotic therapy has altered the normal gastrointestinal flora.
Lactobacilli are bacteria that normally live in the human small intestine and vagina. Lactobacillus acidophilus is generally considered to be beneficial because it produces vitamin K, lactase, and anti-microbial substances such as acidolin, acidolphilin, lactocidin, and bacteriocin. Multiple human trials report benefits of Lactobacillus acidophilus for bacterial vaginosis. Other medicinal uses of Lactobacillus acidophilus are not sufficiently studied to form clear conclusions. The term "probiotic" is used to describe organisms that are used medicinally, including bacteria such as Lactobacillus acidophilus and yeast such as Saccharomyces boulardii . Although generally believed to be safe with few side effects, Lactobacillus acidophilus taken by mouth should be avoided in people with intestinal damage, a weakened immune system, or with overgrowth of intestinal bacteria.