Probiotics are microorganisms with potential health benefits. I never heard about probiotics in medical school. Maybe they are teaching it now, but I've had to do my own research to find out what they are all about.
Probiotics are mainly used to treat GI conditions, including antibiotic-associated diarrhea, infectious diarrhea and irritable bowel syndrome where the microflora of the intestine has been disturbed. When the friendly microorganisms in the body have been disrupted or killed by antibiotics or stress, the homeostasis of the body is thrown off. Restoring the balance and proper immune function by placing new "friendly" organisms into the body is what probiotic therapy is all about.
The organisms we know the most about are in the Lactobacillus species that are naturally found in the human gut. Most probiotics are bacteria (Lactobacillus and Bifidobacterium) but some are yeasts such as Saccharomyces boulardii. The probiotic species must be resistant to acid and bile to survive transit through the upper GI tract and they must be taken regularly to work.
A number of studies have shown that probiotics may reduce the incidence of diarrhea in people who have taken antibiotics. The benefit is the greatest when they were taken within 72 hours of taking the first antibiotic. For adults, the greatest benefit came from doses of a least of 5-10 billion colony-forming units (CFUs).
There are no contraindications to probiotics comprised of Lactobacillus, Bifidobacterium, S. thermophilus or S. boulardii species. There are also no known interactions with medications or other supplements.
Scientific studies have shown benefits from probiotics in infections diarrhea, antibiotic induced diarrhea and irritable bowel syndrome and possibly atopic dermatitis (eczema) in infants and young children. Other allergies such as asthma, food allergy or allergic rhinitis showed no benefit.
Probiotcs are sold as capsules, powder, liquid or placed in foods. A recent study analyzed a range of brands of probiotics and found that of the 19 brands examined, five did not contain the number of live microorganisms stated on the label*. So really knowing the brand and making sure it contains enough CFUs is important.
Traditional yogurt does not usually contain enough probiotics to make a difference but therapeutic yogurts do. Look for Danactive, Activia, Yo-Plus, Stonyfield and Danimals for children.
Warning: Probiotics don't "cure" anything.
More information on probiotics can be found here. and at the National Center for Complementary and Alternative Medicine.
*ConsumerLab.com product review: probiotic supplements.