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How to Buy Probiotics That Work

6 things to look for to help ensure the probiotic you select is safe and effective

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Chances are that you’re familiar with probiotics: They’re sailing off the shelves of drugstores and health food stores nationwide. The market for probiotic supplements in North America rose from $547 million in 2017 to more than $1 billion in 2022, according to market research company Statista. It’s predicted to rise to nearly $1.5 billion in 2027, almost tripling in just a decade.

Many probiotics are sold as supplements, however, meaning that they’re not regulated by the United States Food and Drug Administration (FDA). “This means that it’s really buyer beware out there — companies can throw whatever they want into a supplement and call it a probiotic,” says Tod Cooperman, M.D., the president, and founder of, an organization that regularly tests supplements, including probiotic supplements. “There’s no guarantee that you’re ingesting exactly what the label on the products claim.”

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There are situations when the use of a probiotic can be beneficial, Cooperman stresses. Here’s a primer on how to determine when they’re necessary, as well as how to shop for them.

What probiotics are, exactly

They’re beneficial microorganisms, usually bacteria, like what’s found naturally in your gut. “They help support the balance of good bacteria,” says Gail Cresci, a microbiome researcher in the department of pediatric gastroenterology, hepatology and nutrition at the Cleveland Clinic. They’re found already in fermented foods like yogurt, kefir, kombucha, sauerkraut, kimchi, tempeh and miso. But they’re also available as over-the-counter supplements, in the form of capsules, tablets, powders, chewing gums, gummies and lozenges.             

Probiotics shouldn’t be confused with prebiotics, which are a form of soluble fiber, like inulin, that the good bacteria in your gut loves to feed on, Cooperman notes. They are also different from postbiotics, which are heat-killed probiotics. While you may see both listed on the label of a probiotic supplement, the jury’s out as to whether or not they make the product more effective, he says.

Do you really need a probiotic?

For general overall health, probably no, Cresci says. “We have research that suggests specific strains of probiotics can be beneficial for various health issues such as antibiotic-related diarrhea and irritable bowel syndrome, and can even boost immunity and fight inflammation,” she adds. “But there’s no one strain that can address all these conditions — or even prevent them. We suspect that you need a variety of probiotics to keep your digestive and immune system healthy.”


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The best way to do this, Cresci notes, is through diet. “The bacteria in fermented foods actually release important byproducts like short-chain fatty acids, which can improve your immunity and reduce inflammation in your body. You’ll also be getting a variety of different probiotic strains through food, which is more difficult to get with a supplement.”

But if you have a very specific health condition, such as irritable bowel syndrome, or are taking an antibiotic, then the use of a probiotic supplement may be helpful, Cresci says. Just talk to your doctor first, because “in very rare cases, if a probiotic is introduced into your body, it can cause infection, since it is a live organism. This usually only ocecurs among people who are immunocompromised — for example, they have HIV or are undergoing chemotherapy,” she says.

What to look for in a probiotic

If you have spoken to your doctor, and they agree that it’s reasonable that you should try a probiotic, there are some things to keep in mind when you search store shelves. “The good news is that over the last decade or so, the quality of probiotic supplements has improved dramatically,” Cooperman says. “Initially, the bacteria would die quickly. But companies have gotten a much better handle on how to create and deliver products that still have viable cells in them.”

Here’s what both Cooperman and Cresci say you should look for in order to help guarantee the probiotic brand you select is safe and effective.

1. Colony-forming units (CFUs). This is the number of bacterial cells you get in each probiotic dose. “You want one with at least a billion colony-forming units,” Cresci says. While that may sound like a lot, “these products often lose CFUs while they are traveling,” she adds. “They may sit on the tarmac of an airport for hours in sweltering heat, for example, which kills some of the bacteria off. This way, while you may not get the exact amount listed on the label, you still know you’re getting a good amount.”

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2. A well-researched strain. Look for the names Lactobacillus, Bifidobacterium, or Bacillus, which are some of the most researched probiotics, according to Cresci. “You also want to look for a product that’s been tested and shown to work for your particular ailment,” she says. “If your doctor wants you to take a probiotic because you are on antibiotics, to help prevent antibiotic-associated diarrhea, you don’t want one that claims to prevent respiratory infections.” (See our sidebar for recommendations.)

3. Storage information. You want to keep probiotics refrigerated, since heat can kill bacteria off, Cresci stresses. Also check the expiration date. “CFUs tend to decline over time, which makes them less effective,” she says.

4. Prebiotics. These are forms of soluble fiber, like inulin, that probiotics feed off. “You want to make sure that the probiotic you buy has some sort of food source, so that it doesn’t die off,” Cresci says.

5. Capsules. In general, you’re better off with capsules than other forms, like powders or gummies, Cooperman says. “They offer the most protection against gastric acids that can destroy bacteria before they reach your intestine.” This is particularly important if your probiotic contains the strains Streptococcus thermophilus or Lactobacillus bulgaricus, which are easily destroyed by stomach acid, Cresci notes. If, for some reason, you need to take a probiotic in a liquid, powder, or gummy form — for example, you have trouble swallowing pills — Cresci recommends that you take it with food to help counteract the effects of stomach acid.  

6. Opt for name brand. Cresci advises paying a little extra for a name brand that actually has clinical research to back it up. “This way, you know for sure that the product has been tested for whatever you’re looking to address,” she says. “This is particularly important, since probiotics aren’t regulated by the FDA — since they are sold as supplements. You want to make sure that you’re getting the strains that you really want.”

Which Probiotic Strain Should You Take?

Here’s what Cooperman recommends you look for, based on the latest research and’s 2022 probiotics report.

Antibiotic-related diarrhea and traveler’s diarrhea: Culturelle Probiotics Digestive Health and FloraStor. The strains in both have been shown to help reduce or prevent diarrhea, Cooperman says.

Constipation: Gerber Soothe Probiotic Colic Drops (contains Lactobacillus reuteri DSM 17938). Five drops given twice daily has been shown to reduce constipation in adults.

Irritable bowel syndrome: The American Gastroenterological Association doesn’t recommend using probiotics to treat IBS, citing lack of evidence. But there is some research to suggest several Lactobacillus, Bifidobacterium and Streptococcus strains, found in Visbiome High Potency Probiotic, may help with diarrhea symptoms, Cooperman says.

Respiratory illness: “Many probiotics claim to provide immune support, but it’s a very vague claim,” Cooperman points out. There is some evidence that probiotics that contain strains of Lactobacillus or Bifidobacterium may help reduce symptoms of upper-respiratory infection, especially if they are taken consistently throughout cold and flu season. For example, Lactobacillus plantarum and Lactobacillus paracasei — a combination found in Metagenics Ultraflora Immune Booster — shown to reduce the number and severity of colds in adults. 

Vaginal infections: Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 appear to reduce the risk of vaginal infections like yeast or bacterial vaginosis in women. These strains are found in Jarrow Formulas Fem Dophilus and RepHresh Pro-B Probiotic.

Cholesterol lowering: Lactobacillus reuteri NCIMB 30242 (found in UAS Labs’ LRC) has been shown to lower total cholesterol and LDL (bad) cholesterol by more than 9 percent after nine weeks.