Probiotics, bacteria that when eaten in sufficient quantities can be beneficial, have become common on grocery store shelves.
They’re found naturally in fermented foods like kimchee, sauerkraut or kefir, and added during the manufacturing process into some dairy products, cereals, juice, baked foods and fermented meats, like sausage.
Their popularity is based on the notion that boosting the number of “good bacteria” in one’s body to fend off infections and other ailments is akin to calling in ground troops to fight off a foreign invader.
It sounds logical that the more soldiers in the fight, the better the odds of winning.
The problem is, scientists haven’t figured out yet which bacteria to call on, how many are needed, or even how they do battle with “bad bacteria.”
But that hasn’t stopped food manufacturers. Probiotic supplements, fortified foods and specialty nutrients have become big business, worth $35 billion globally in 2015 and expected to grow to more than $50 billion by 2022.
While difficult to know how much Canadians are spending on foods with added probiotics, a 2014 Health Canada report on “functional foods,” which includes fortified milk and yogurt, noted it’s the fastest-growing agricultural sector in Canada, generating revenues of more than $11 billion.
That’s despite limited evidence to show that probiotics hold the promise that marketers would have consumers believe.
Probiotics have long been associated with fad diets, starting in 19th century Paris, where the bacteria in sour milk was promoted as a way to prevent aging. The term probiotic was coined in the 1960s and covers a multitude of microorganisms, including strains of lactic acid bacilli; a non-pathogenic strain of e. coli; clostridium butyricum that’s usually found in sour milk and cheeses; streptococcus salivarius, a bacteria typically found in the mouth or upper respiratory tract; and a non-pathogenic strain of yeast.
(It’s worth emphasizing that these are findings of studies conducted by the makers of probiotic food products. Wider meta-analyses looking at the overall quality and quantity of data puts it plainly: “enthusiasm for probiotics has outpaced the scientific evidence.”)
For now, Health Canada regulations restrict food manufacturers from making claims about the benefits of consuming probiotics. They may only say probiotics are part of “good gut health.” To be called “probiotic,” Health Canada requires that foods contain at least a billion bacteria per serving.
That sounds like a lot – but it’s not always enough, says Mary Scourboutakos, a research associate at the University of Toronto who looked at the health benefits of probiotic dairy products.
Not all products are created equal
Scourboutakos found that different dairy products marketed as containing probiotics had different bacterial strains and different dosages. For some products, the amount of bacteria contained in a single serving wasn’t enough to achieve health benefits claimed during industry-sponsored trials.
A consumer would have to eat between eight and 25 servings of Activia, for example, to feel the effects found during studies sponsored by Danone, the yogurt’s maker and the world’s largest seller of yogurt, which included decreased flatulence, stomach rumbling and improved stool consistency.
“This is where things become less useful for consumers,” Scourboutakos says. “You wouldn’t want to consume that much yogurt. But without it, you can’t get the benefit that’s been shown.”
That hasn’t stopped consumers from filling their fridges. According to Fortune magazine, there were $2.7 billion sales of Activia in 2016, up from about $130 million in 2006, before it was marketed with the promise of probiotics.
Such is the power of advertising to convince consumers that the benefits of adding a clinical-sounding substance, like probiotics, are well-known and well-researched.
“With probiotics, everyone has more questions than answers,” Scourboutakos says.” It’s very complicated and really nothing is black and white. It also depends on the individual because we all have a different eco-system inside of us. The effect it has on you will depend on what environment you’re introducing it to.”
Given the potential for profit, the food industry is pouring research dollars into figuring out just what probiotics can do. Danone is reportedly spending a significant portion of its $313 million research and development budget to not only plumb the bugs’ potential, but also to engineer and patent new bacterial strains.
Probiotics are also being studied for their potential to prevent or treat a range of illnesses, including diarrhea, irritable bowel syndrome, allergies like eczema or hay fever, tooth decay and other oral health problems, colic, liver disease and necrotizing enterocolitis, a condition that destroys bowel tissue in 10 per cent of premature babies.
However, a 2015 review of studies related to the use of probiotics for a range of health issues, from constipation to colitis to lactose intolerance and pancreatitis found “most studies have been small, and many have important methodological limitations.” There was not yet enough evidence to conclude probiotics worked more effectively than proven therapies in preventing or treating various ailments.
But researchers are working to fill some gaps.
Deborah Cook, a critical care physician at St. Joseph’s Health Centre in Hamilton, Ontario and the Canada Research Chair in Research Transfer in Intensive Care, is midway through a Canadian-led trial looking at whether probiotics can reduce a critically ill patient’s chance of developing new infections, such as pneumonia or antibiotic-related diarrhea.
“In the high technology, fast-paced environment of the ICU, there is no question that new devices and molecules have helped to improve the care and the outcomes of very sick patients,” she says. “But I’ve also always been drawn to more simple, readily available and less expensive interventions to see if they too could be beneficial even if used in ways differently than in the past.”
Gregor Reid, the Endowed Chair in Human Microbiome and Probiotics at the Lawson Health Research Institute in London, Ontario, is researching the use of probiotics in women’s urogenital health and whether probiotics can help protect against exposure to heavy metals, by binding metals to the bacteria, which are then expelled through the feces.
Reid says the food industry’s interest in probiotics is a double-edged sword. While average Canadians now know the word, they don’t necessarily understand its importance.
It’s important for impartial bodies to devote research dollars to exploring the potential uses of probiotics, Cook says.
“It’s great that Canadian granting agencies acknowledge the need to better understand their possible role in prevention of serious infections in seriously ill patients, because sometimes it’s well-established, widely available and inexpensive interventions that can actually make a difference. Benefit doesn’t always follow new, costly or only specially-available therapeutics,” she says.