Eat Your Germs

By Sanjay Gupta, M.D.

No doubt you have heard that yogurt is teeming with bacteria--and no doubt you try not to think about that as you dig into a cup of the stuff. Yes, they're supposed to be good bacteria, ones that not only don't make you sick but actually improve your health. Still, a spoonful of critters with unlovely names like Lactobacillus reuteri, Lactobacillus rhamnosus and Bifidus regularis will never sound like a palate pleaser to even the most dedicated health nut.

Whether or not you've ever developed a taste--or even a tolerance--for living things in your lunch, more are on the way. Food companies have been coming to the conclusion that if a few of these superstar bacteria are good for you, then more will be even better. This is giving rise to a small but growing product line called probiotics, in which the bacteria population is boosted, sometimes considerably. For consumers, of course, the question is, Do these products work?

Probiotics have been around for a long time, mostly in the form of dietary supplements. They're also found naturally in foods like yogurt, buttermilk, sauerkraut and tofu. Recently, however, the Dannon Co. has been making a marketing splash with a yogurt line named Activia, which is fortified with extra bacteria. So far, this bet seems to be paying off, with more than $100 million in sales in the product's first year in the U.S. alone. Other companies are coming forward with probiotic yogurt drinks and fortified beverages, which are also finding a market. There is a fair body of science suggesting that some consumers are spending their dollars wisely.

"The superstar bacteria stick around in your intestines a lot longer," says Dr. Gary Huffnagle, a professor of internal medicine at the University of Michigan and co-author of The Probiotics Revolution. In the digestive tract, the bacteria help regulate and restore peristalsis, the rhythmic motion of the intestine that pushes digested food through. There's a reason one of the bugs has the word regularis as its second name, and this intestinal toning is it. "Doesn't matter if you are constipated or the opposite," Huffnagle says. "These bacteria can help make you, um, regular."

Huffnagle's research also suggests that the bacteria can battle numerous kinds of allergies--and not just food allergies. This is a somewhat harder scientific case to make, but Huffnagle's belief is that since anything you breathe you may also swallow in at least some quantity, the good bacteria in your gut could help control allergens.

Not everyone is sold on probiotics. The U.S. Food and Drug Administration is relatively neutral, using the growing popularity of the products as an opportunity to caution manufacturers not to pitch the foods as some sort of panacea for any specific disease. More important, some people should avoid the products altogether. Those with weakened immune systems or who are critically ill would be well advised to stay away from eating live bacteria. Certainly anyone in the hospital would also count. Furthermore, the products can take a little getting used to, even for the otherwise healthy. If you are new to the world of probiotics and you suddenly start eating a lot, there is a good chance you could experience uncomfortable bloating.

"You have just started a civil war in your intestines between good bacteria and bad bacteria," Huffnagle says. Fortunately, the war is usually over in one or two weeks, and, stresses Huffnagle, "the good guys win."

Expect to see lots of those good guys on store shelves soon. At least five companies in the U.S. either are in the probiotic game or are planning to enter. Plain yogurt remains the best product for added bacteria because it has three things the bugs absolutely love: lactose (or naturally occurring sugar), fat and water. Another food out there with both sugar and fat is chocolate, and--you guessed it--the company Attune already has a probiotic chocolate bar. That's something that may prompt me to give the superstar bacteria a try after all.

PROBIOTIC BACTERIA [This article contains a table. Please see hardcopy of magazine.] Name What it's said to do Foods that may contain it Bifidus regularis Regulates the movement of food through the digestive tract Yogurt Lactobacillus casei Inhibits the growth of harmful bacteria; boosts immunity Cottage cheese Lactobacillus acidophilus Aids digestion; diminishes effects of bad bacteria in the intestines Cereal

Sanjay Gupta's Fit Nation series airs on House Call on CNN, Saturdays and Sundays, at 8:30 a.m. E.T.