If you religiously pop a probiotic pill every morning, you’re not alone. Since they rose to prominence in the U.S. in the 1990s, probiotics, the strains of “good bacteria” found in foods like yogurt, have become a de facto miracle cure for gut health issues and other pesky ailments.
Around 4 million Americans take probiotic supplements. Medical providers often prescribe them to patients with gut health issues, such as ulcerative colitis and inflammatory bowel disease. They might also recommend them to people with other conditions, including rheumatoid arthritis, eczema and even urinary tract infections.
Today, the World Health Organization defines probiotics as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.” Some research suggests that doses of “good bacteria” can fix imbalances in your gut flora, in turn helping ease some of these ailments.
Despite years of popular usage, many of the studies on probiotics have been poorly designed, and supporting evidence remains limited in scope, due to the large number of probiotic strains that exist. The American Gastroenterological Association recently cleared some things up. In a new report, it stopped short of recommending probiotics for most common digestive conditions, like Crohn’s disease and irritable bowel syndrome, only suggesting use of the microbes in three different clinical scenarios.
“Given widespread use and often biased sources of information, it is essential that clinicians have objective guidance for their patients about the appropriate use of and indications for probiotics,” the report reads.
As this news comes to light, it’s essential for patients to understand why the supplements became so popular in the first place and where they should fit within medical advice going forward.
Putting the “pro” in probiotic
“Probiotics have been around for a really, really long time,” says Lynne McFarland, an associate professor of medicinal chemistry at the University of Washington. Foods full of healthy bacteria, like kefir and kimchi, have been a natural staple in humans’ diets for centuries.
But science didn’t technically catch on to their health benefits until the early 1900s. After studying a group of Bulgarian centenarians, Russian biologist Elie Metchnikoff claimed the “good bacteria” in their yogurt was helping them fight the impacts of aging, sparking a global craze for the tart treat.
Yakult, the first commercially available probiotic drink, was born in Japan in 1935, before scientists were even using the word “probiotic.” Researchers finally coined the term in the 1950s. “Probiotic” served as an antithesis to “antibiotic”; while antibiotics notoriously destroy gut bacteria, probiotics are supposed to restore it. Much of the field’s early research determined which strains of bacteria could actually pass through the gut into the intestines to offer benefits to the patient.
Given the popularity of Yakult, business leaders latched onto these findings, despite shaky research behind them, launching something of a probiotic revolution.
Microbes, marketing and medicine
As probiotics infiltrated the commercial market, they also became more widely accepted in the medical community.
In 1994, American legislators passed the Dietary Supplement Health and Education Act, which allowed probiotic manufacturers to sidestep a lengthy FDA drug approval process and fast-track their products to shelves. “When the dietary supplement law was passed, it was like opening Pandora’s box,” says McFarland.
Under the law, companies that make dietary supplements, including vitamins, protein powders and probiotics, can make health claims on their labels with little proof of their validity. But McFarland estimates that about one-third of the probiotic supplements out there either don’t have the strains they claim to have on the label or don’t have enough of the probiotic strain needed to have an effect.
The label’s commercial success seeped into the medical world. From 2006 to 2012, probiotic usage in hospitals in the U.S. nearly tripled, illustrating just how popular the microbes had become among medical providers.
Today, there are studies that suggest that probiotics, in the form of a pill or foods like yogurt, can be helpful in restoring good bacteria after a dose of antibiotics. But questions still remain about their efficacy. Many health care providers remain skeptical that one dose of a few probiotics can really influence a person’s unique microbiome, made up of billions of strains of different bacteria.
“There are hundreds of species and trillions of cells in the gut microbiome,” says molecular biologist Emma Allen-Vercoe, a professor at the University of Guelph. “You might be orally taking a capsule of one species, and it’s got to transverse through your guts, and by the time it gets to where it’s going, some of it or most of it will be dead, and the rest will be in competition with a whole army of other microbes or other species inside you.”
To kick or keep?
We’ll likely never see probiotics stamped from the landscape. While their hype is overblown, certain strains and combinations can offer health benefits. Doctors continue to recommend them to patients because the risks are generally pretty low. (You can find a list of clinically recommended strains here.)
Going forward, there’s still so much more research to be done on probiotics and the human microbiome. As scientists pick up the pace on these investigations, we’ll likely see more recommendations from medical bodies on the use of microbes for health.
In its new report, the AGA cautions gastroenterologists against recommending probiotic supplements to patients if there is no clear benefit. And there is some evidence that the risks of probiotics are greater than previously thought: A small 2019 study shows that taking probiotics can sometimes interfere with patients’ immune systems.
No matter what, if you’re considering taking a probiotic supplement to help with a medical condition, talk to your doctor.
Dietitian Jerlyn Jones, for instance, recommends a food-first approach to her clients with gut health issues. She advises they try yogurts and kefir products before picking up a bottle of pills at the drugstore.
Meanwhile, Melissa Prest, a dietitian and spokesperson for the Academy of Nutrition and Dietetics, tells her patients that probiotic supplements can’t hurt. She gives them guidelines so they can be discerning about what they’re purchasing. “We need to be mindful of what health conditions we are treating and with which strain of probiotics,” she says.
If you simply want to take a probiotic to boost your health, Allen-Vercoe says don’t bother. Over and over, evidence suggests that probiotics offer little benefit to already healthy people.
“It’s very tempting to say, ‘I’m just going to take this probiotic and everything will get better,’” says Allen-Vercoe. “The reality is we all have to take a bit more care of ourselves through diet and exercise.”