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Understanding pros and cons of probiotics

Athos Bousvaros, MD, is the associate director of the Inflammatory Bowel Disease Program at Children's Hospital Boston. He specializes in gastrointestinal care of children with special needs, inflammatory bowel disease and pediatric gastroenterology.

What is the difference between probiotics and prebiotics?
Probiotics are live bacteria that you ingest. The bacteria then pass into the digestive tract and enter the intestine, where they promote health. This healthy bacteria (micro flora) can be found in foods such as sauerkraut and yogurt. Prebiotics are not bacteria at all. They are nutrients, typically non-absorbable carbohydrates such as fructo- oligo-saccharides, which are found in legumes, fruits and whole grains.

What role do intestinal bacteria have in maintaining health?
The intestine is home to about 400 different species of bacteria. Some of the bacteria might promote health by digesting food, producing vitamins, preventing infection and regulating the immune system. Therefore, a popular theory is that if you supplement people with good bacteria, you can more favorably colonize the gut and promote good health.

In what circumstances would probiotics be used?
Probiotics are frequently used in treating stomach bugs, having shown the most impact on infants with acute diarrhea. Infants who get rotavirus or other viral illnesses typically have diarrhea for three or four days. Probiotics have been shown to decrease the duration of the illness by a day. The fundamental question is, is it worth taking a pill for a few days to shorten the number of days with diarrhea from three to two?

The other areas where we usually use probiotics in gastroenterology are food allergy and irritable bowel syndrome. Sometimes we use them in children with bacterial overgrowth. We also use probiotics to prevent bacterial infection, Clostridium difficile, also referred to as C. difficile or C. diff. There is a probiotic called saccharomyces boulardii that prevents recurrent C. diff. We sometimes try probiotics in irritable bowel syndrome, but I think the best proof is really in viral acute diarrhea in children.

What is the role of probiotics in atopic diseases such as eczema, asthma and allergies?
This is an area that is still under active investigation, but some studies suggest they might be beneficial in alleviating the symptoms of these conditions. Two of the best studies were conducted in Finland and Australia. In Finland, Dr. Erika Isolauri studied pregnant mothers with strong allergy histories. During the third trimester of pregnancy, the mother took the probiotic lactobacillus GG. After birth, the same probiotic was fed to the infant for six months. A second group took a placebo for comparison. This study concluded that infants who were fed the placebo had a 40 percent rate of allergy, primarily eczema. Infants fed the probiotic had a 20 percent rate of allergy.

The second study focused on treatment. It was conducted by Dr. Susan Prescott in Australia. She gave infants between the ages of 6 and 18 months with eczema a probiotic or placebo. Compared to the placebo, the probiotic showed a mild affect, seeming to lessen the severity.

Who can use probiotics?
People of any age can use them. They appear to be safe for babies, although I wouldn't use them in babies under the age of 1 month. People with compromised immune systems and central venous lines need to be very careful when using probiotics because there have been rare reports of bacterial infection in such patients.

Do you think there is a type of probiotic that is better than others?
There are probably 200 different products available for purchase. Some of these have been studied and published in medical journals, while others have not. Some have very high quality control and purity, while others do not. A physician recommending these to a patient should not just recommend any probiotic for purchase off the shelf in a health food store. He should really ideally restrict his recommendations to the probiotics that have published data supporting their use. It is important that more studies be performed to determine which probiotic and which prebiotic works best for which illness.

What should people know about probiotics?
While there is a lot of enthusiasm about probiotics being a "natural cure," there is not enough data to conclusively say that they help autoimmune disease or human health. When recommending something like a probiotic to a patient, the pediatrician needs to be aware of what research has been done and tell the patient, "buyer beware." I think that is true with any complementary therapy. Patients need to do their own research. These are the questions that you need to ask:

• Which probiotics have been formally studied in patients?
• Are the bacteria inside the bottle live and active?
• What is the quality control used in manufacturing the products?
• What is the optimal dose?
• Which probiotic should be used to treat a specific condition of a disease?

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