Thursday, March 31, 2005

Lurking In Your Yogurt: Live Cultures That May Boost Immunity

Chicago Tribune

March 28, 2005

Bacteria in your food are a bad thing, usually: Think of E. coli or other harmful bugs. But a whole other world of "friendly" bacteria lurks out there. Called "probiotics" and found in such products as yogurt and yogurt drinks, they provide health benefits beyond the regular live cultures found in those foods.

Probiotics are among the fastest-growing category of functional foods, according to the market research firm Mintel, which cites a 140 percent increase last year in the launch of new probiotic-fortified products.

So far, the strongest evidence on probiotics has focused on digestive- tract problems such as lactose intolerance and diarrhea-including infectious diarrhea among children and the type that develops after a person has taken antiobiotics (which wipe out both good and bad bacteria in their path, altering the natural balance of the digestive tract).

Additional studies suggest probiotics may help decrease the risk of colon cancer and ease symptoms of irritable bowel syndrome and the more serious inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis. Researchers also are beginning to see signs that probiotics may help lower blood pressure and blood cholesterol levels.

Europeans have long embraced the concept of probiotics (which is derived from the Greek word meaning "for life"), but Americans haven't fully warmed up to the idea of downing a drink swimming with billions of live microorganisms.

"We've done a good job in this country of scaring people to death of microbes," said Mary Ellen Sanders, president of the International Scientific Association for Probiotics and Prebiotics, a non-profit scientific organization. "People don't understand the important role microbes can play in our health."

Unlike antibiotics, which kill harmful microbes in the body, probiotics simply take up temporary residence and neutralize the negative effects of the "bad" bacteria living there. Some of the benefits of probiotics appear to be their feisty aggression toward these nasty bugs in our bodies, Sanders said.


Some of the most exciting research on probiotics involves its potential to boost immunity, according to Allan Walker, a professor of nutrition and pediatrics at Harvard Medical School, who is studying how exposure to good bacteria could help children decrease their susceptibility to infections and allergies.

Probiotics appear to communicate with the cells in our intestines to turn on antibodies to fight infections, Walker said. This "cross-talk" helps rev up our immune response so we're better prepared to deal with invading bacteria and viruses that could make us sick, he said.

Though research is preliminary, scientists are revealing some promising immune function benefits, particularly among children:

-Finnish researchers cut in half a baby's risk of developing allergies early in life by giving probiotics to expectant mothers and their newborns who were predisposed to asthma, hay fever and eczema.

-A recent study published in Pediatrics found that infants fed formula containing probiotics had less diarrhea and fever, and fewer clinic visits and absences from child care centers, compared to those who consumed a formula without probiotics.

-A seven-month study of more than 570 children in day care centers found that intake of a probiotic milk reduced the number and severity of respiratory infections and the need for antibiotics.


Some foods may be made with microbes-everything from sourdough bread to pickles, sauerkraut, kim chi, miso and fermented meats like salami. But it doesn't mean all the "good bugs" survived the processing or that the strains used provide actual health benefits, which is required before it would qualify as a probiotic, Sanders said.

You also can't assume that all yogurts contain probiotics (although not all experts agree on where you draw the line). Though many of the national brands contain "live active cultures," the typical strains used to make yogurt don't make it the full ride through our digestive tract.

These starter bacteria produce lactic acid and are used to give yogurt its tart flavor, but they don't seem to have the same types of health benefits as probiotics, which do survive the digestive tract, Sanders said (although they still might help folks with lactose intolerance).

If you want a yogurt with the gut-healthy, friendly bugs, you need to scour the label to see if the manufacturer supplemented the standard strains with probiotic bacteria. The two most common are Lactobacillus acidophilus and bifidobacteria (or bifidus). You won't necessarily see the word "probiotics" on the label.

These bacteria (and their probiotic cousins L. casei, L. reuteri and others) also are being added to fermented milks like acidophilus milk, kefir and soy beverages.

New to the market is Dannon's DanActive, a probiotic dairy drink that contains 10 billion live cultures per serving-or 10 times more cultures than yogurt, according to the label. DanActive also appears to be the first product to use the immunity claim to try and sell Americans on the benefits of live microorganisms. The label touts its ability to "naturally strengthen your body's defense system."

Companies are exploring adding the cultures to a wide range of non-dairy products, including breakfast cereal, energy bars, juices and other beverages, and even candy. Capsules of probiotics also are available in health food stores, but experts believe there may be additional benefits of getting your bacteria in a food form, especially through dairy products.

To take care of the "good" bacteria you buy, don't let your probiotic products linger at room temperature, and don't heat them or you'll kill the live cultures. Also, it's best to consume probiotics before the use-by date on the label (or within the week following the sell-by date). Otherwise, the live cultures begin to die off.

To reap the full benefits, you need to consume probiotics on a regular basis. The friendly bacteria only persist in your gut as long as there's a steady supply. So if you don't eat any foods or supplements containing probiotics, after about a month they will be gone.


Now that you've gotten to know the term "probiotics," there's something else you should add to your lexicon: prebiotics.

These are types of dietary fiber, such as inulin and oligosaccharides, that help nourish the growth of good bacteria. Companies are beginning to introduce new products that contain a combination of probiotics and prebiotics.

Consuming foods that naturally contain prebiotics-garlic, onions, artichokes, bananas and whole grains-also can help stimulate the good bugs that naturally reside in your digestive tract.

(c) 2005, Chicago Tribune. Distributed by Knight Ridder/Tribune News

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