So what’s a probiotic? It’s a food, drink, or supplement that contains bacteria or yeasts thought to be beneficial to your gut’s microbiome. While there’s research to suggest probiotics may help some people avoid or overcome certain health conditions, the evidence is “not as solid” as nutraceutical companies and supplement makers would have you believe, says Stephen Freedman, MD, a probiotics researcher and associate professor at Alberta Children’s Hospital.
Here, Freedman and other experts explain what you need to know before you pick up a probiotic supplement.
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What’s Good For Someone Else May Not Help You
“The question that always comes up with patients is, ‘Which one should I take?’,” says Emeran Mayer, MD, PhD, a professor of digestive diseases at UCLA and author of The Mind-Gut Connection.
Mayer says there are hundreds of probiotic strains linked to positive health benefits in certain patient populations. For example, some studies suggest that you can treat a yeast infection with products containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14, while Bifidobacterium animalis DN 117-001 seems to help more with digestion.“But while some get a benefit from these strains, others actually have worse outcomes,” he says.
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Your individual microbiome is unlike anyone else’s. “There’s about 90% variation from one person to the next,” Mayer says. So until health scientists have a way of mapping your microbiome to spot gaps or deficiencies, choosing a probiotic will be a bit of a crap-shoot, he says. (Here's the single best thing you can do for a healthier gut, and it doesn't involve pills.)
Dosage And Other Specifics Are Murky
Freedman says that, up to this point, probiotics-makers have not approached their supplements using the same deliberate methods drug-makers are required to use when developing pharmaceuticals. “Consequently, we have very little data on duration of therapy, dose, frequency, etc,” he says.
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Basically, no one can tell you how much of a probiotic to take, how often to take it, or when to expect results, he says. As of right now, it’s all guesswork.
The Exact Benefits Aren’t Yet Clear
It’s true that research has linked probiotics to everything from reduced anxiety to better immune function. But Freedman says most of that research is preliminary—and some of it’s questionable.
“Many probiotic studies have been positive as it relates to improving gastrointestinal symptoms, but concerns exist in the medical community regarding the quality of the studies,” Freedman says.
While there’s reason for optimism, he says it’s too soon to say for sure whether probiotics can safeguard your health or cure what ails you.
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The Jury Is Still Out On Whether They Change Your Microbiome
Ingesting a probiotic and having that probiotic shift the makeup of your microbiome are two very different things. “In many cases, a probiotic will not colonize a person’s GI tract or induce microbiome changes,” Mayer explains.
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Asked if refrigerated probiotics may be more likely than packaged “shelf-stable” pills to set up shop in a person’s gut, he says that’s not something we know at this point. Again, your guess is as good as an expert’s.
Placebo Effect Is Likely A Factor
With any type of supplement, there may be a large placebo effect at play, Mayer says. Meaning, if your brain thinks you’re taking a probiotic that will make you feel better, that may cause you to feel better even if the effect is not caused by the probiotic. “We know that stomachaches and gut conditions are very influenced by placebo,” he adds. This is another reason some “positive” studies need validation.
All That Said, Probiotic Supplements Probably Aren’t Harmful
Mayer says most of the research suggests probiotics aren’t harmful—especially if you’re healthy. “If you’re very sick, I wouldn’t recommend taking any supplement without asking your doctor,” he says.
Even if you’re well, he says he’d be more likely to recommend natural food sources of healthy bacteria—stuff like kefir or sauerkraut—over a probiotic supplement. People have been eating these foods for centuries, so we know they're safe. Plus, whole food sources of probiotics may be preferable, as they contain additional nutrients as well.
“Asking me what I use for my own family, it would be one of these natural food remedies,” he says.
You can also bolster your diet with foods containing prebiotics, nondigestible carbohydrates that help spur the growth of probiotics in your gut. You'll get those from things like whole grains, bananas, onions, garlic, asparagus, Jerusalem artichokes, dandelion greens, and jicama.