The Good Bugs

When Little Miss Muffet sat on her tuffet eating her curds and whey, she may have been doing more than filling her tummy.

“Curds” is an old word for yogurt, and evidence is mounting that some of the bacteria contained in yogurt can prevent and treat diarrhea. They may also ease other ailments of the intestinal tract, and some researchers now advocate using these beneficial bacteria — “probiotics” — as medicine.

“They’re not as tried and true as Pepto Bismol,” says Gary Elmer, Ph.D., a professor of medical chemistry at the University of Washington. “But probiotics are worth a try.”

The digestive tract is home to more than 400 species of bacteria. Researchers believe that at least some of these native bugs crowd out invading organisms that cause illness, by using resources that the bad bugs need and producing chemicals that kill them. Eat more of the helpful bacteria, the theory goes, and you can stave off stomach problems.

“It seems to work with the body’s natural defenses to prevent the overgrowth of a bad bug,” says Sherwood Gorbach, M.D., a professor of community health and medicine at Tufts University in Boston.

Bacteria as Medicine

Gorbach discovered Lactobacillus GG, one of the most thoroughly studied probiotics. Research shows it significantly cuts the rate of many types of diarrhea, particularly the type that develops after a person has taken a course of antibiotics. The drugs often wipe out every bacterium in their path, good and bad, altering the natural balance of the digestive tract.

Lactobacillus GG is one of a handful of probiotic bacteria strains available over the counter in capsule form. It soon may be available in yogurt.

Don’t Count on Yogurt

Raw or unpasteurized yogurt — Miss Muffet’s curds — is loaded with bacteria. But most commercial yogurt is pasteurized, a process that kills bacteria. Though a few investigators have found promise in pasteurized yogurt with live bacteria added, most research has focused on capsules containing specific strains of bacteria. “It is generally agreed that a probiotic must be capable of colonizing the intestinal tract to influence human health,” says Gorbach. “This requirement disqualifies many of the strains currently used in fermented dairy products.”

If you have diarrhea, are about to take antibiotics, or plan to travel to a developing country, advocates say there’s no harm in trying probiotics. “I wouldn’t hesitate at all,” says Gorbach. “There’s no downside.” But to avoid damage to your wallet, choose supplements containing bacteria that have been shown to have positive results. In addition to Lactobacillus GG, these include Lactobacillus johnsoni, Lactobacillus reuteri, and Bifidobacterium.

Published February 10, 2000