Health & Wellness

The Facts About Probiotics

Before you go shopping for a probiotic, here are some things to keep in mind 

By Wendy Haaf


Based on her experience as a clinical pharmacist with a Hamilton, ON, family health team, Dragana Skokovic-Sunjic believes that most people who are taking probiotics—live organisms that, when consumed in adequate amounts, confer a health benefit—are wasting their money.

One problem, she says, is that her patients don’t think to mention any probiotic products when reviewing the list of prescription medications and over-the-counter remedies and supplements they’re taking unless Skokovic-Sunjic specifically asks. More importantly, when she probes more deeply—such as asking about the kind of probiotic they’re taking, and why—the vast majority have only a vague sense that taking a probiotic is somehow a good idea.

“I would say that 95 per cent of my patients who are taking probiotics are taking the wrong probiotics, or are taking them for no reason,” she says.

That’s not surprising, given that the probiotic industry is rife with misinformation, hype, and borderline deception, thanks in part to hefty profits and the fact that regulations around natural health products are much more lax than those for prescription drugs.

“Unfortunately, people get bombarded with all kinds of different messaging, some of it completely false and some of it not quite right,” says Gregor Reid, a professor at Western University and the director of the Canadian Centre for Human Microbiome and Probiotic Research at the Lawson Health Research Institute in London, ON. “That makes it very tough for the consumer.”

So what do you need to know before you go shopping for a probiotic? Here are some of the most important things to keep in mind.

Many fermented foods do not contain probiotics. 

While some people assume “probiotics,” as they understand the term, are present in foods such as kimchee, sauerkraut, and yogourt, the term applies only if a particular bacterial strain “has been documented and shown to be probiotic,” Reid says, as is the case with probiotic-supplemented foods such as DanActive yogourt.That’s not to say that including these foods in your diet has no value—for one thing, doing so may help maintain robust, diverse populations of the gut microbes responsible for tasks such as making certain vitamins. In fact, Reid says he “tried to get Health Canada to recommend one fermented food in the diet each day” for exactly that reason. “They just ignored me,” he says.

There’s a lot we still don’t know about the microbiome and how probiotics work.

Scientists are still in the early days of working out which specific species of bacteria and other organisms, and in which proportions, constitute a healthy microbiome (the microbial ecosystem inside the gut). They’re also still looking into whether there’s a universal “healthy” microbiome or whether there are more than one healthy combination of gut microbes.

“We’re just at the beginning of understanding the role of the microbiome in health,” says Dr. John Marshall, a professor of medicine and the director of the Division of Gastroenterology at McMaster University, and a member of the Farncombe Family Digestive Health Research Institute in Hamilton, ON.

“We still need to discover which microbes are foundational,” says Dr. Thomas Louie, a clinical professor at the University of Calgary’s Cumming School of Medicine.

Nevertheless, we have a reasonably good idea of some of the steps you can take to nurture the health of the beneficial beings in your gut, beginning with a diet rich in a wide variety of plant foods. (For tips, an e-book, How to Shape a Healthy Microbiome, can be downloaded from the University of Calgary’s website, explore.ucalgary.catype the title into the search field. The tips provided may be particularly relevant to the over-55 crowd, since the diversity of the gut microbiome tends to decline with age, which some experts postulate may predispose one to developing various health problems.)

Our understanding of how probiotics influence our health is still evolving. Initially, the thought was that, once consumed, these live, beneficial bacteria would remain in the gut and possibly multiply, crowding out other, potentially harmful microorganisms. However, it’s now generally understood that probiotics typically don’t stay put, and while they may compete with “bad bugs” while passing through, they also produce substances that help protect the gut lining and likely communicate with the immune system and the brain. (The gut contains the body’s largest supply of serotonin—a chemical messenger that, when in short supply in the brain, is linked with depression.)

You should have a specific goal in mind. 

“You don’t go to the pharmacy and say, ‘The doctor told me to get a drug,’” Skokovic-Sunjic points out. “The pharmacist has to know which medication you need, for what reason, and for how long.” The same goes for probiotics, starting with the effect you’re hoping to achieve. Do you want to reduce your chances of catching common infections? Ease symptoms of irritable bowel syndrome? Cut down on cavities? Perhaps you’re simply hoping to help maintain a robust microbiome?

The goal is to use a product containing a microorganism that has been studied and found to be effective for your preferred given use. “‘Probiotic’ is very much an umbrella term,” Marshall explains. “It encompasses the species of bacteria,” as well as the dose—that is, the concentration of live microorganisms used in positive clinical trials. “Essentially, you have to look for products that have been tested in humans and shown to have an effect,” Reid says.

Fortunately, there is a free resource you can consult to get this information: Clinical Guide to Probiotic Products Available in Canada: Indications, Dosage Forms and Clinical Evidence to Date. Available online and in app form (, the guide is updated annually by a panel of experts led by Skokovic-Sunjic.

“We match the probiotic product or strain with the outcome and the indication that is based on a clinically relevant study,” she says. “We do not promote specific names or brand names.” If there are two or more such products in a particular category available on the Canadian market, “we list them alphabetically,” Skokovic-Sunjic says. It’s also worth noting that each year, after she and her colleagues weigh the evidence on each product, including any new arrivals on the market, before any changes are made to the guide, “we have to have unanimous consensus,” she says.

Manufacturers may swap microorganisms.

Sometimes the rights to the microorganism in a particular product will be sold to another company and the original manufacturer won’t necessarily change the brand name or packaging. “Things change from year to year, which keeps us on our toes,” says Skokovic-Sunjic. “Products may change a strain without announcing or marketing it. For example, a product that was in hospital formularies for the prevention of antibiotic-associated diarrhea contained a strain with really good evidence behind it, but in 2009, the product lost the rights for that specific strain.” The original company quietly replaced the evidence-backed strain with another. “They used another strain that has no clinical evidence,” Skokovic-Sunjic says. “It’s harmless, but it does nothing.”

Other examples include a product containing a strain of bacteria which had been shown—largely via research conducted in Canada—to lower LDL (bad) cholesterol. “That strain now belongs to a US company,” Skokovic-Sunjic says, and it’s now marketed under a different name. However, “it’s not available in Canada yet,” she says. Similarly, at one time, there were two yogourts on the market that each contained a combination of two probiotic bacteria that, together, could help lower fasting-blood-glucose levels in people with Type 2 diabetes: one of the yogourts has since been discontinued completely, and the other now contains only one, not both, strains.

Not every yogourt contains live bacteria, much less probiotics. 

Yes, yogourt is made by adding certain strains of bacteria to milk, but once these microorganisms have done their job, some brands are exposed to heat, thereby killing the bacteria and halting fermentation (brands that are not pasteurized do contain live culture). In the case of probiotic-fermented milk products such as certain yogourts, the probiotic strain—which will happily survive in this medium without continuing fermentation—is added afterwards. And as with any other probiotic, those in such products need to be taken in the appropriate dose to exert the desired effect.

Multiple strains aren’t necessarily better.

“There are myths and misconceptions that are rampant,” Skokovic-Sunic says, and one of these is the idea that the more strains, the better. As you may have guessed by now, in the absence of any evidence to the contrary, it’s impossible to say whether a cocktail of specific bacterial strains is beneficial for a particular symptom or condition, or even for overall health.

In the same vein, organisms that require refrigeration aren’t necessarily better—read product labels for storage instructions, since the ideal conditions will vary from one product and strain to another. Nor are more expensive products necessarily superior. As with other natural health products, “there’s a lot of variation in quality,” Marshall says, and “sometimes what’s in the bottle is not what’s on the label. So look for a trusted manufacturer and a trusted point of sale.”

Some people should consult a health professional before starting a probiotic.

Probiotics are generally safe and well-tolerated, the main side effect being what some people describe as a gurgling in the stomach, which typically isn’t bothersome or long-lasting enough to consider stopping taking the probiotic. However, if you’re thinking about taking a probiotic to treat a specific problem, it’s a good idea to check with your primary care provider beforehand. “A probiotic could mask symptoms,” Skokovic-Sunjic explains, and potentially prevent or delay a diagnosis of a more serious underlying issue.

Moreover, “there are certain populations that should be very careful when using probiotics,” she adds. Specifically, if you have a condition that impairs your immune system, if you’re taking medications (such as chemotherapy drugs) that suppress this condition, or if you have a venous catheter, consult a health professional, such as the specialist who’s guiding your treatment.

There are indeed conditions for which specific probiotics appear to be helpful.

A number of these involve the gut. For instance, certain strains can help prevent antibiotic-associated diarrhea. “That’s probably one of the scenarios where there’s more evidence,” Marshall says. “It’s not universally effective, of course, and it probably varies a lot from person to person.”

There’s also evidence supporting the use of specific formulations for preventing travellers’ diarrhea and constipation, as well as for easing symptoms in a subset of patients with irritable bowel syndrome. Probiotics may also be helpful—albeit only in particular situations—for inflammatory bowel disease.

Taking certain probiotics during and for a few days following a course of antibiotics can reduce the risk of developing diarrhea due to C. difficile infection—the most frequent (and potentially life-threatening) cause of infectious diarrhea in hospitals and health care facilities. A 2017 review by the respected Cochrane collaboration found that when probiotics were taken with antibiotics, risk for C. difficile-associated diarrhea (CDAD) was reduced an average of 60 per cent, with an even more pronounced benefit among high-risk patients, at a 70 per cent reduction in risk. Dr. Louie and doctors John Conly and Jayna Holroyd-Leduc are currently conducting a study in four Calgary hospitals to see if, when given with antibiotics to patients 55 or older, a Canadian probiotic preparation can reduce the rate of C. difficile infections.

There are also products that appear to reduce the frequency of common infections such as cold and flu, as well as others that may lessen symptoms of anxiety.

If you’re simply looking for a daily probiotic for general health, “things like DanActive, Bio-K+, and Activia have had human studies done on them, so they’re at least reliable,” Reid says.

As the science evolves, we may very well learn of as-yet-undiscovered probiotics and ways of using them to fight and prevent a variety of ills, perhaps including brain conditions such as dementia.

“I and many of my colleagues have a lot of optimism that microbiome therapy,” including probiotics, “is going to be the answer to lots of human health challenges,” Marshall says.

Photo: iStock/vgajic.