If you’re new to the world of probiotics, start with our general health pick, Islands Miracle Ultra-30 Probiotics. It boasts over 30 billion bacteria cultures and more expert-recommended bacteria strains than any other probiotic on our list.
If you have a specific ailment or want to switch up your current probiotic routine, we chose products with bacteria strains will well-documented health benefits: MegaFood MegaFlora helps your system recover after taking antibiotics, Renew Life Ultimate Flora Extra Care strengthens your immune system, and Dr. Formulas Nexabiotic Advanced Multi-Probiotic eases IBS and IBD symptoms.
We also found strain combinations that address everything from weight loss to decreased anxiety — though that research is limited. Still, any probiotic supplement is going to make some improvement on your digestive health, so don’t be afraid to experiment.
How We Found the Best Probiotic Supplement
We started our search with the most popular products from major supplement retailers like Amazon, Drugstore.com, GNC, and Whole Foods. That gave us over 200 supplements.
With so many options, we then narrowed our search to 70 probiotics whose purity, potency, and projected efficacy have been vetted by an independent lab, like ConsumerLab, Labdoor or the NSF. Because supplement claims aren’t regulated by the Food and Drug Administration (FDA) regulated, we wanted to make sure someone was testing whether they worked as described.
From there, we made sure each supplement had at least 1 billion CFUs per serving.
CFUs — colony forming units — are the number of active live organisms inside the bacteria. As a general rule, a probiotic should provide at least 1 billion CFUs. While a probiotic with fewer CFUs isn’t a bad choice, a supplement with more stands a better chance at being effective. Supplements with more than 100 billion were out too — those are only recommended in specific circumstances by your doctor, like if your body doesn’t naturally produce enough probiotics. While there’s little risk of overdose, too much can cause abdominal pain like cramps and bloating.
And cut anything with only one strain of bacteria.
Though it may seem like a targeted assault would be the way to go, research suggests that probiotics work better as a team. Even pairs can be more effective than individuals. Take the strains Lactobacillus Acidophilus and Bifidobacterium Bifidum BB-12, for example. When combined, this duo-force has been shown to help treat a nasty, antibiotic-resistant GI infection. In fact, 75 percent of studies that compared the effect of a strain mixture with a single strain supplement showed that a mixture was more effective at improving irritable bowel symptoms, immune function, and digestive health.
Selecting a multi-strain probiotic is also consistent with the theory that if you cram your gut with enough types of good bacteria, it will out-compete any bad bacteria for the same space and resources. Think of it this way: In an environment where rabbits are overpopulating because of an excess of tasty clover, introducing wolves will help. Introduce horned owls as well? Even better. In your gut, the more diversified that good bacteria is, the harder it is for the baddies to gain a foothold. So any supplement with only one strain got the boot.
Then, we took a closer look at the bacteria.
At this point, we had 32 solid options. But to find the best, we wanted supplements with bacteria strains that have have the most evidence of being truly effective. We dug through probiotic studies on The National Center for Biotechnology Information, dissected ConsumerLab’s extensive report, and verified those findings with our experts.
Dr. Michelle Schoffro Cook explained there’s no single best strain of bacteria, though some strains like L. acidophilus or B. bacterium have wide-reaching effects. They often act as a starting point from which to add other strains with more specific effects.
We found the most evidence linking strains to support antibiotic recovery, immune health, and IBS/IBD relief. For our general health pick, we tracked the strains that came up in the most studies and came recommended by our experts. They’ll give you a little bit of everything.
We also found strains linked to five other health benefits like weight loss and lowering cholesterol — but those effects aren’t as heavily researched as immune health or IBS relief. Either way, they’re still good for your gut.
From there, we narrowed our list to the supplements with high ratios of targeted bacteria combinations relative to their overall CFU count. If two products were similar, we chose ones with minimal additives and better Labdoor scores.
That left us with ten probiotic supplements that met our basic criteria andhad an ideal combination of bacteria strains for a variety of health benefits.
We looked for guaranteed viability too — that is, bacteria that will still be alive when we swallow it.
Bacteria die out over time. Some supplements list the potency when it was manufactured (before it rode in a truck, sat on the shelf at the grocery store, or hung out in the kitchen cupboard for a few months). There may be dramatically fewer viable bacteria by the time you consume them than when they were first encapsulated, and good bacteria are no good to you dead.
The best probiotic manufacturers will list their potency (in CFUs) at the time of expiration, ensuring that you get the dosage that you’re paying for. Dr. David Perlmutter, board-certified neurologist, American College of Nutrition Fellow, and author of The New York Times best-sellers Brain Maker and Grain Brain puts it this way: “Avoid products that indicate a specific number of bacteria ‘at the time of manufacture,’ and instead look for products that, like other supplements, have a shelf-life.”
We purchased all of our picks to examine the labels up close. We’re happy to report each supplement had a specific “best by” or “expires on” date clearly printed onto the bottle.
Our Picks for the Best Probiotic Supplement
Maybe you don’t have a specific health goal in mind, but you do want to bolster the number of good bacteria floating around your system. Dr. Perlmutter recommends starting at a minimum of eight to 10 different bacterial species, including a core five: L. Plantarum, L. Acidophilus, L. Brevis, B. Lactis, and B. Longum. We included these five in a larger a list of the ten most researched and universally beneficial strains in a general digestive health pick — we wanted a probiotic that would work for everyone.
Islands Miracle Ultra-30 Probiotics has 18 different strains total, and it includes nine of the ten we wanted in a general health probiotic. Each serving comes with 30 billion CFUs per serving; the label recommends you take two supplements per day. We also like that they’re also gluten and dairy-free — ideal if you already have a sensitive stomach.
When we opened the bottle, we noticed a slightly sour smell — common with all the probiotics we tested. But it’s subtle, and the individual capsules don’t have a noticeable scent.
Antibiotics wreak havoc on your microbiome by decimating both good and bad bacteria — an effective treatment if you have an infection, but without the gut good guys, you’ll come out the other side of any course of antibiotics with a weaker immune system. Potential side effects aren’t so pretty either: vomiting, diarrhea, and even susceptibility to a C. Diff infection. It’s tempting to think of probiotics as re-populating your post-apocalyptic gut with good bacteria after the fallout from antibiotics. Not quite.
Most of the bacteria native to the human microbiome aren’t in probiotics. To truly “repopulate” your system, you’d need a human fecal transplant (exactly what it sounds like) and you’re not going to find that in a jar.
Luckily, certain probiotic strains can help with antibiotic-associated symptoms in other ways. Taking relatively high doses of these probiotic strains before, during, and after antibiotic treatment can help your microbiome get back on its feet: B. Lactis, B. Infantis, L. Acidophilus, L. Casei, L. Bulgaricus, L. Paracasei, L. Rhamnosus GG, S. Boulardii. Our antibiotic combatant MegaFood MegaFlora has six of these strains, as well as eight others. One serving contains 3 billion CFUs, a concentrated dose to replenish the good bacteria. You’ll want to keep the bottle in the fridge — this can sustain the life of the CFUs. The label clearly indicates it should be stored cold and was even shipped with an ice pack.
The capsules are quite tiny, about the length of a pinky fingernail. These could be super easy to drop and misplace, but also easy to take if you have trouble swallowing pills — and you only have to take one a day.
In addition to the prophylactic effect of stocking your gut with good bacteria, there are some probiotic strains that can even improve immune function, and some have even shown promise in treating symptoms of certain autoimmune disorders.
- Planatarumand L. Paracaseiin particular can improve immune function with as little as 500 million CFUs daily, and a combination of L. Acidophilus and B. Lactis at 2.5 billion CFUs twice daily has been shown to improve upper respiratory infections.
Renew Life Flora Extra Care has all four targeted bacteria strains, at 30 billion CFUs per serving. The capsules are a bit bigger than the penny-sized Islands Miracle probiotic, but you only have to take one a day, and it’s still no horse pill. Renew Life also earned the highest Label Accuracy score from our picks tested by Labdoor (87 out of 100). Impressively, this means you’re more likely to get the bacteria and CFUs that the product is advertising — a difficult feat for sensitive bacteria that die off.
It’s worth noting that, like MegaFoods MegaFlora, the Renew Life label recommends cold storage. But that recommendation is printed so small we nearly missed it (and it didn’t ship with a cold pack).
There has been a lot of research on treating IBS and IBD symptoms with probiotics, much more than on most other pathologies. There are many strains proven to alleviate symptoms — L. Acidophilus, and E. Faecium came up again and again in our research.
Dr. Formulas Nexabiotic Advanced Multi-Probiotic has both of these and five other relevant species (with 23 strains total) in its 34.5 billion CFU serving. This product also had the highest overall Labdoor score of our picks at 92.4 out of 100. It’s a normal-sized capsule, slightly smaller than the Renew Life Flora Extra Care, and has a faint peanut butter smell — less sour than the other probiotics we looked at.
Other Probiotics to Consider
The research on probiotics is still in its infancy, but it seems that probiotics can do a lot more than just keep you regular. We put together our top picks based on which strains had substantial evidence backing up a concrete health benefit, but we also came across some studies that surfaced some lesser-known benefits of taking probiotic supplements, like decreased anxiety.
While there’s not as much research to support their claims, these probiotics still have plenty good-for-your-gut bacteria. Not all of these supplements contain every relevant strain, but they checked off the most boxes where it counts.
Did You Know?
There is still a surprisingly small amount of research on probiotics.
Although the idea of beneficial bacteria has been around since the late 1800s, and probiotic supplements have been around since the 1930s, there haven’t been many human clinical trials.
We do know that probiotics produce enzymes that help break down chemicals that the average human gut has a hard time with, such as the oligosaccharides in legumes. That digestive assistance results in less gastrointestinal distress and better absorption of nutrients.
Probiotics also elicit an immune response in the intestines that can help your body deal with certain harmful pathogens and other GI problems. There is actually a mechanism we learned about called cross-talk where, through chemical signals, the bacteria communicate with your body, and your body communicates back.
The hard research, especially on recommended CFU dosages, is minimal but expanding as interest in the product does.
You can get probiotics (and prebiotics) from certain foods.
Some foods are made by the addition of bacteria — yogurt, pickles, cottage cheese, kombucha, and sauerkraut for example. And those foods work to provide the same probiotic benefits as supplements. However, most foods are so processed and pasteurized that it’s unlikely you’d be able to get enough to see the same benefits as you would with a supplement, let along the right strains. Regardless, it certainly can’t hurt to be getting extra probiotics through your diet.
You’ll also want to get enough prebiotics too. Prebiotics are complex sugars ingested as fuel for gastrointestinal bacteria. Some probiotics include them in the supplement, but the amount is usually too small to make an impact, and you’re likely already getting enough in your regular diet.
There are tons of prebiotics that probiotics love in whole fruits and vegetables, including onions, garlic, bananas, asparagus, unpasteurized apple cider vinegar, and artichokes. If you’re worried you might not be getting between five to 20 grams per day (a bowl of onion soup), consider taking a prebiotic supplement, usually a powder or drink mix. Dr. Perlmutter recommends acacia gum.
Keep up your probiotic routine and mix it up.
The benefits you gain from your probiotic will cycle through your body if you don’t take them regularly. Probiotics stick around for a while, though for how long isn’t precisely clear. You have to keep taking them to continue to reap the benefits. Further, getting a wide variety of strains into your system is beneficial. “Periodically mixing up your probiotic supplement is also a good way to ensure that you get different health-building strains in your health regime,” says Dr. Cook.