Smart Shopping for Probiotic Supplements

Probiotic supplements contain bacteria and yeasts that are purported to balance and regulate the organisms that normally reside in the GI tract. An imbalance in GI tract organisms can be caused by an illness or the use of certain antibiotics. Diarrhea is a tip-off. Probiotic organisms put the squeeze on disease-causing organisms by competing with them for nutrients, producing chemicals that damage or inhibit them, and by stimulating the immune system.

2 organisms that have been proven to prevent diarrhea caused by antibiotics are Saccharomyces boulardii and Enterococcus faecium, as well as Lactobacillus species. Other species of yeast and bacteria have proven helpful against the organism that causes human ulcers. So far, no particular bacterial or yeast strain has provided reliable protection against traveler's diarrhea. Probiotics are under study for other GI conditions.

What to Look for

Probiotics are available in yogurts, capsules, tablets, drinks and powders. Make sure that the product you purchase lists the names of the bacteria and yeast it contains. These are typically in Latin and italicized. The most common and best-studied species include the Lactobacillus species: L. acidophilus, L. bulgaricus, L. casei, L. gasseri and L. plantarum. Also look for Bifidobacterium species: B. bifidum, B. lactis and B. longum. Depending on the manufacturer, other species may be used as well, although some of these don't have as much research to back their use.

If you buy yogurt to get a probiotic, stick to brands that say they have live or active cultures.

Some products have enteric coatings so that the organisms survive the passage through the high-acid stomach and reach the intestines alive. The most common probiotic species don't really need this coating, however.

Common Pitfalls

Probiotic products are very sensitive to heat, dampness and exposure to oxygen. The number of organisms that a product contains when it is first packaged is often diminished by the time you purchase it. These are both good reasons to check a product's expiration date before you make a purchase.

When storing a probiotic, shield it from heat, light and moisture. Experts recommend refrigerator storage for most products.

Some people notice an increase in intestinal gas when they start taking a probiotic. This usually is a temporary inconvenience. There have been cases in which people with serious illnesses have experienced bacterial blood infections as a result of taking probiotics. A recent study looked at the use of probiotics in people with severe, acute pancreatitis as a way of preventing complications. It turned out that probiotics did not reduce the complication rate, and more people actually died in that group of severely ill, hospitalized people.

Don't confuse a probiotic with a prebiotic, which are sugars that GI bacteria use for fuel.