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Probiotics are live organisms often referred to as 'friendly,' or good, bacteria

Carolyn Tucker, age 50, is passionate about eating well. Her lifestyle choices are healthy and, almost always, calculated. She never eats junk food. Why? Because she knows it promotes obesity and heart disease. She buys organic vegetables and fruit. Why? Because she knows they're crammed with disease-fighting antioxidants minus the pesticides. She practises yoga regularly. Why? Because she knows it strengthens her body, mind and soul.

She also eats yogurt with probiotics. Why? Here, she's not so sure. "I have no idea why," she laughs. A nutritionist recently suggested she buy probiotic yogurt, so she follows that advice, though somewhat robotically. "I can't even remember what it was good for, but I did switch and that is now what we eat," says Toronto-based Ms. Tucker, who is married with two teenaged boys.

Like Ms. Tucker, most Canadians have only a vague notion that probiotics are healthy. Certainly, we are inundated with advertising about yogurt containing probiotics. But we're not sure what they are, which ones are good for us, how many we need, and what the science says about them.

Probiotics are live organisms often referred to as "friendly," or good, bacteria. The most in-depth scientific studies on them to date are in the area of digestion; research in other areas is piling up now.

"We are learning that probiotics have numerous health benefits," says Toronto doctor of naturopathic medicine Dr. Tracey Beaulne. "The list seems to be endless … digestive health, oral health, skin, brain, urinary tract and our immune systems." Dr. Beaulne practises at Bayview Natural Health Clinic and at the Active Therapy Clinic at the Granite Club in Toronto.

Probiotics are classified by genus (you might recognize names like Bifidobacterium, Lactobacillus, or Streptococcus), species (such as casei, plantarum, bulgaricus, or johnsonii) and strain (for instance DN-173 010 or DN-114 001). Activia yogurt, made by Danone, for example, contains Bifidobacterium animalis (lactis) DN-173 010. There are millions of different strains of probiotics, so it would take a thick health dictionary to keep them all straight.

No wonder we're befuddled. Think of probiotics as you would think of antibiotics: different strains treat different conditions. One strain might be good for antibiotic-induced diarrhea and another for treating irritable bowel syndrome.

Here's how they work: "Good bacteria create a barrier or film-like coating over the inner lining of the intestinal wall. This film keeps toxins and bad bacteria from gaining access through the wall and into your bloodstream," says Dr. Beaulne.

According to a study in the Journal of the American Dietetic Association, the benefits of regular consumption of probiotics include enhanced immune function, improved colonic integrity, decreased incidence and duration of intestinal infections, a decrease in allergic reactions, and improved digestion and elimination. What is less clear is exactly which specific strains are best, what dosages and form they should be taken in, how much is safe, and how long they last on the shelf.

"This is not sufficiently summarized to allow practical and consistent recommendations to be made by most food and nutrition professionals," says Dr. Beaulne. She relies on clinical experience and individual health concerns to guide her patients.

She does recommend yogurt as a source of probiotics, but warns that flavoured yogurt is generally high in sugar and fillers such as corn starch. While Danone's Activia is good for the digestive system, as shown in clinical trials, she says, it does not come in a plain unsweetened version, so it contains a lot of sugar: 13 g per 1/2 cup.

BioK yogurt is another good source of probiotics. Like Activia, BioK has been tested in clinical trials. Even better, says Dr. Beaulne - "they also have a no-sugar one that I like."

Dr. Beaulne often recommends patients take their probiotics in supplement form. For patients with allergies, asthma and eczema, she recommends Culturelle Lactobacillus GG. It isn't readily available in Canada, but many health food stores import it from the United States.

For inflammatory bowel disease, she recommends a supplement containing eight strains of probiotic, called VSL#3, which is widely available in Canada.

For diarrhea, there's Lactobacillus rhamnosus GG (sold under the Valio brand), B lactis BB12 with Lactobacillus acidophilus La5 (Chr. Hansen), and Lactobacillus reuteri SD2112 (Biogaia).

For urogenttal health, the above strains and other strains, such as L rhamnosus GR-1, L reuteri RC-14 (Chr. Hansen), and Saccharomyces boulardii LYO (Biocudex).

Lactobacillus plantarum 299V (Lallemand) is used for reducing hospital-acquired infections, and Lactobacillus casei Shirota (Yakult) for perhaps reducing recurrence of bladder cancer. All are in various stages of entering the market, says Dr. Beaulne.

Ms. Tucker's attitude towards probiotics is typical: they're healthy -but spare us the details. "I am generally very well informed on nutrition and health issues because that is my passion and interest. If I had to guess, I would say that very few, if any, of my contemporaries know anything about probiotics and most really wouldn't care."

What's the simple message? If you just want to boost your general gut health, eat yogurt with probiotics. For more specific concerns, visit a naturopath, dietitian or nutritionist who can guide you toward a specific strain.

Special to The Globe and Mail