Probiotics: man alive! Live microorganisms may be the secret to good health

Ever notice the phrase on a cup of yogurt: "Contains live active cultures"? While this statement may worry the squeamish, it shouldn't. These single-celled bacteria happen to be an effective means of ensuring digestive health, and they may have more far-reaching benefits.

In this day of antibacterial everything, it's hard to imagine bacteria being beneficial. However, certain bacteria--including the yogurt-dwelling L. acidophilus--are, in fact, good. They belong to a group of healthy, live microorganisms called probiotics.

Don't let their long scientific names scare you because they can make even the most science savvy tongue-tied. When reading labels, it is the probiotics' category name that comes first, and then the species name follows. In our yogurt example, Lactobacillus is the genus or category--abbreviated L.--and acidophilus is the species.

Research on each of these main categories has shown that certain strains can relieve digestive ailments such as diarrhea, irritable bowel syndrome (IBS) and lactose intolerance. Other studies suggest that probiotics may be able to boost immunity, prevent colon cancer and lower cholesterol. Here's the scoop.

You want to: Improve digestion and heart health

Reach for: Lactobacillus acidophilus

What the research says: L. acidophilus got a thorough research review in the February 2001 issue of the Journal of Dairy Science. Conclusion? Taken daily, this probiotic seems to help people who are lactose-intolerant digest dairy foods.

L. acidophilus has also shown promise for protecting heart health. Researchers at the National Taiwan University have found that some probiotics, including L. acidophilus, can lower total cholesterol levels in animals.

You want to: Boost your immunity

Reach for: Lactobacillus casei

What the research says: Taking L. casei supplements may improve disease defenses, even in the face of malnutrition, according to an Argentinean animal study that showed L. casei improved immunity and the response to a respiratory infection. These results were published in the June 2005 Journal of Nutrition.

However, L. casei may not be effective for preventing diarrhea if you're healthy. A report by David Pereg, MD, and researchers at the Sapir Medical Center in Kfar-Sava, Israel, showed a "nonsignificant" effect against diarrhea in healthy men who consumed L. casei.

Yet despite these results (published in the March 2005 issue of the American Journal of Infection Control), Pereg still touts the gains of probiotic supplementation. "Probiotics have many other potential benefits besides preventing infections," he says. "They may lower cholesterol, improve bowel function, etc. We believe that it may be beneficial to add probiotics to the diet."

You want to: Reduce IBS symptoms

Reach for: Lactobacillus rhamnosus

What the research says: As Pereg suggests, the benefits of probiotics go beyond preventing infections. Specifically, Finnish researchers just reported that a combination of probiotic strains--including L. rhamnosus GG, L. rhamnosus, Bifidobacterium breve and Propionibacterium freudenreichii-reduced IBS symptoms by 42 percent. For details, see the September 2005 issue of the journal Alimentary Pharmacology & Therapeutics.

You want to: Relieve digestive disorders such as diarrhea

Reach for: Saccharomyces boulardii

What the research says: In January 2005, Turkish research found that S. boulardii reduced the severity and duration of diarrhea in children. These results appeared in 2005 in the Swedish journal Acta Paediatrica. In September 2005, another study showed that S. boulardii is "moderately effective" in preventing antibiotic-associated diarrhea, as reported in Alimentary Pharmacology & Therapeutics.

You want to: Strengthen gastrointestinal (GI) immunity

Reach for: Bifidobacterium bifidum

What the research says: The elderly are particularly susceptible to GI infections because the amount of natural microbes in the body decreases with age. However, a combination of B. bifidum, B. lactis and an inulin-based prebiotic (a starch that promotes the growth of probiotics) increased the size and diversity of elderly patients' protective intestinal flora or microorganisms, according to researchers at the University of Dundee in the United Kingdom. Their research was published in January 2005 in Clinical Infectious Diseases.

You want to: Promote good colon health

Reach for: Bifidobacterium lactis

What the research says: A combination of B. lactis and prebiotics may also help prevent colon cancer. Richard Le Leu, PhD, and his team at Flinders University of South Australia found that B. lactis plus a resistant starch called Hi-maize reduced DNA damage in animal colon cancer. The research was reported in the May 2005 Journal of Nutrition. Le Leu explains: "If cells become damaged or mutated in the large bowel of humans, then a diet [containing these substances] may be helpful in removing these cells."