I've seen a lot of foods that include probiotics, which are supposed to be good for the stomach. Do these really work? Should I try to choose cereals, yogurts, and other foods that include probiotics?
Probiotics are bacteria or yeasts that are beneficial to the person in whom they live. There are several types, including lactic acid bacteria (e.g., Lactobacillus and Bifidobacterium), a strain of E. coli that does not cause disease, and a yeast (Saccharomyces boulardii).
The interest, both commercially and medically, in probiotics is probably a little ahead of the scientific proof. However, they truly do seem useful in the treatment of some digestive diseases, such as ulcerative colitis and acute infectious diarrhea, or in preventing antibiotic-associated diarrhea (which occurs in people who are taking, or have recently taken, antibiotics). The common chronic malady of irritable bowel syndrome has not had convincing evidence of being helped by probiotics. But these microorganisms are generally safe, so some may consider them worth trying for various intestinal conditions even if unproven. There is also some interest in probiotics use for allergies, but there is no evidence that we all should be consuming these little pals for general health purposes.
Probiotics are not approved by the Food and Drug Administration, which can be problematic for doctors, as it's impossible to order a standardized preparation like one can for a drug. And as they are not medications, they are usually not covered by insurance. But you have to love a treatment that you can take in the billions. To reduce the symptoms of infectious diarrhea, the minimal effective dose of lactobacillus appears to be 10 billion colony-forming units given within the first 48 hours. So when it comes to intestinal bacteria, you too can be a billionaire.
