The Best Probiotic Supplement

It’s a jungle in there

The 30-Second Review

Probiotics are all the rage, but there's not a ton of science on them yet. To find the best strains — in the best combinations — we talked with a neurologist and New York Times bestselling author, a board-certified doctor of natural medicine, and an internationally recognized probiotic microbiologist. Our findings revealed the best ones have clinical evidence of their efficacy (and zero junk ingredients).

Top Picks
Best for General Health

The stats on this probiotic are pretty astounding: 50 billion CFUs of 33 bacteria strains, including the core five recommended for general health. At $0.98 per pill, it's more expensive than the average per-serving cost of $0.69.


MegaFlora also has the core five bacteria for general health — it scored second place because it has a lower number of strains (14) and a lower CFU count (20 billion), but it also has a lower price tag to match (only $0.48 per serving).

Our Other Top Picks

You’re not living alone in your body. In the humble human gut, there are hundreds of trillions of bacterial occupants, and they’re not just living there — they’re working for you. In addition to their more infamous duties of keeping the GI trains running on time, that gut flora makes up 70–80 percent of the human immune system and plays a central role in regulating inflammation in the body. The best probiotics, like our top pick, Garden of Life RAW Probiotics Colon Care, have bacteria strains proven to be clinically effective and contain no junk ingredients. Even better, they’re guaranteed to have viable doses; after all, we want those guys alive, not dead.

A small but growing body of research on our gut tenants suggests that hacking your microbiome can not only improve the digestive process, but also contribute to a laundry list of ancillary health benefits. We’re talking weight loss, lower cholesterol, decreased anxiety, improved immune function, fewer seasonal allergy symptoms, and relief from a host of gastrointestinal malities, from irritable bowel syndrome to travelers diarrhea. We’re in! But we’re also skeptical.

Whenever we hear about a product with such a prolific and dramatic list of benefits, especially ones that don’t seem straightforwardly linked, we’re a little inquisitive (and aren’t surprised that you are too). So, we started by finding out exactly how and why probiotics work. We interviewed industry experts and analyzed the findings of 169 clinical studies and the results of a third-party lab test to identify the right strains and their minimum effective dosages.

Our Picks for the Best Probiotic Supplement

Best Probiotic for General Health

Garden of Life RAW Probiotics Colon Care Garden of Life's impressive ingredients list more than makes up for its slightly higher-than-average asking price.

Maybe you don’t have a specific pathology or health goal in mind, but you do want to get more probiotics in your diet to bolster the amount of good bacteria floating around your system. Dr. Perlmutter recommends starting at a minimum of eight to 10 different bacterial species, including the core five: L. Plantarum, L. Acidophilus, L. Brevis, B. Lactis, and B. Longum. Both our top picks for general health have this lineup, plus a handful of other beneficial strains.

Runner-Up for General Health

MegaFlora Probiotics It’s got 20 billion active bacteria and 14 strains, including the core five — at about half the cost of Garden of Life RAW.

Garden of Life is one of the most trusted brands in the probiotics market and for good reason: Its strain profiles are of extremely high quality and well-researched. At first we were critical of the “Eastern European RAW Fruit and Veggie Blend” of cherries, peas, and carrots that make up 45mg of the overall ingredients. Would that leave room in the capsule for enough bacterial might? Oh yes. The bacterial contents are pretty astounding: 33 strains, including the core five, at 50 billion CFUs per pill. At $0.98 per serving, this supplement costs a little more than the average $0.69 per serving, but well under some of the more expensive options that can reach upward of $6.

Best for Antibiotic Recovery

Custom Probiotics 11 Strain Probiotic Powder While it may not have the name recognition of others in the industry, Custom Probiotics impressed us with its high quality and potent ingredients list.

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. 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.

However, 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.

Runner-Up for Antibiotic Recovery

Garden of Life RAW Probiotics 5-Day Max Care The 5-Day Max Care is formulated with gut flora replenishment in mind: 34 probiotic strains and an enormous 400 billion CFUs. At $5.99 per serving, though, it is the most expensive supplement we looked at, especially since the five-day program may not even cover a full antibiotic treatment, let alone the ideal pre and post treatments.

Best Immune-Booster

Renew Life Ultimate Flora Extra Care 30 Billion Renew Life’s Ultimate Flora Extra Care hits all the right notes when it comes to price, CFU count, and ingredients.

In addition to the prophylactic effect of stocking your gut with good bacteria, there are some probiotic strains that can actually improve immune function, and some have even shown promise in treating symptoms of certain autoimmune disorders. L. Planatarum and L. Paracasei in 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.

Though it’s not explicitly formulated for immune health, Renew Life’s Ultimate Flora Extra Care contains all of the requisite strains for immune boosting, plus an additional two Bifidobacterium and four Lactobacillus strains. We liked this supplement for its respectable CFU count (30 billion, a solid choice for an everyday supplement), right-around-average price point, and an ingredients list blessedly devoid of fillers, harmful ingredients, and common allergens.

Best Probiotic for IBS/IBD/Acute Infectious Diarrhea

VSL#3 Those with IBS, IBD, or Acute Infectious Diarrhea should take a look at VSL#3 or its more potent, prescription-based version, VSL#3D.

There has been a lot of research on treating IBS and IBD symptoms with probiotics, much more than on most other pathologies. VSL#3’s prescription formulation (VSL#3D) has been at the center of several pivotal studies on the subject and has been proven to be clinically effective — extremely rare for a probiotic supplement. The over-the-counter option has less than half as many CFUs, but is the exact same formula strain for strain. You can buy 225 billion CFUs daily without a doctor’s signature for $1.70 a serving; with one you can get 450–900 billion.



Beneficial Strains

B. Coagulans
B. Infantis
B. Longum
E. Faecium
L. Acidophilus
L. Bulgaricus
L. Helveticus
L. Paracasei
L. Plantarum
L. Rhamnosus GG
S. Boulardii
S. Thermophilus

B. Infantis
E. Faecium
Escherichia coli Nissle
L Helveticus
L Plantarum
L Rhamnosus GG
L. Acidophilus
S. Boulardii

B. Breve
B. Infantis
B. Longum
L. Acidophilus
L. Bulgaricus
L. Paracasei
L. Plantarum
L. Reuteri
L. Rhamnosus GG
S. Boulardii
S. Thermophilus

Other Probiotic Supplements to Consider

The research on probiotics is still in its infancy, but it seems that there’s a lot more that probiotics can do than improve “time to discharge” and other trademarks of the lower intestines.

Through the course of our research, we came across a number of studies that indicated some lesser-known benefits of taking probiotic supplements, like decreased anxiety. We put together our top picks based on which strains had solid evidence backing up a connection. Not all of these supplements necessarily contain every relevant strain, but they checked off the most boxes where it counts.

  • Weight Loss

    Relevant strains: B. Brevis, B. Lactis, L. Acidophilus, L. Gasseri, L. Rhamnosus GG
    Our Pick: MegaFlora ($44)

Curious about the other 16 probiotics that passed all our cuts? These guys all have guaranteed potency on multiple bacterial strains — plus no junk or marketing ploys.

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 normal 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.

What you read on the probiotics label is part truth, part hype, and part marketing.

As internationally recognized probiotic microbiologist Dr. Mary Ellen Sanders told us, “There’s often a gap between the hype and the science; the hypothesis versus what’s been demonstrated. People like to tell stories: My probiotic will survive stomach acid and others won’t. Instead look at the clinical benefit.”

Unlike the clinical studies, the bottles don’t have to tell the whole truth. “Dietary supplements are marketed for the general population. They are not marketed for at-risk or patient populations, and companies are not obligated to establish safety for these populations,” Dr. Sanders said.

This is because probiotics are classified as Dietary Supplements by the FDA, meaning that manufacturers “are not required by FDA to undergo rigorous premarketing evaluations for efficacy or safety.” In fact, every bottle of probiotics on the market invariably has this fun little disclaimer printed on it:

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This is caveat emptor (“let the buyer beware”) times a thousand. The burden is entirely on you to take the label’s claims that it’ll “balance your gut bacteria” or “boost your immunity” with a grain of salt, and to talk with your doctor before you start popping capsules.

Probiotics are basically in hibernation.

Relatively few probiotic supplements contain what you might consider “active” bacteria. They are usually dehydrated (through freeze-drying, spray drying, microencapsulation, etc.), which causes the bacteria to go into hibernation until they’re reconstituted in the body. This process makes them shelf stable, though we encountered a lot of conflicting opinions about whether or not cold storage really makes a difference. Some probiotic supplements require refrigeration to ensure maximum potency, and even probiotics that don’t necessarily require cold storage still typically recommend it to slow down cell death and prolong shelf life. This has led to a widespread belief that all probiotics must be refrigerated, and that any brand that claims to be stable at room temperature can’t possibly support viable bacteria.

To get to the bottom of this, we took two probiotic supplements from our top contenders list that didn’t require refrigeration and used them as starter cultures for yogurt. We made a timelapse of the process.

Boom. Those yellow-ish blobs are growing cultures, proving our shelf-stable probiotics from Bio-Kult and Renew Life passed. If you’re ever in doubt of the efficacy of your supplements, it’s an easy test: Just dump one serving in a quarter cup of milk or soy milk, and let them do their thing overnight at room temperature. If your milk turns lumpy or starts to firm up like yogurt, congratulations! You have real live probiotic bacteria. If you’re left with plain milk, consider calling the company to cash in on its viability claims.

You don’t need an enteric coating.

The human digestive system is a pretty inhospitable place for most organisms, and probiotic bacteria are only useful when they make it through the high-acid environment of the stomach. Though most probiotic strains are acid-resistant, many companies use enteric coatings, which protect the probiotics until they’re past the pylorus — the trap door in the bottom of your stomach.

Seems pretty smart, until you start looking at what actually goes into making an enteric coating. In addition to being expensive, the coating process involves a lot of heat, which can compromise bacterial viability. Even more troubling, many enteric coatings contain things like shellac, vinyl acetate, and phthalates (though there are some enteric materials that aren’t sketchy like alginate and hypromellose). There is enough substantial clinical evidence to suggest that probiotics survive, thrive, and get results even without enteric coatings.

The Bottom Line

The science is still young, but we know a few things: Probiotics work better in a pack; prebiotics are just a marketing ploy; and shelf life matters most. Look for multi-strain products and check for a “viability guarantee” through the expiration date to make sure your probiotics will be in full force when you take them.

Take Action

Best for General Health

Garden of Life RAW Probiotics Colon Care Impressive ingredients from one of the most trusted brands.

Start small. Generally, it’s best to start out with a lower CFU count and ramp up as needed. Starting out with the high-proof stuff can cause unpleasant physical side effects, like cramps and bloating, as well as monetary ones — higher potency supplements are almost universally more expensive. Of course, follow your doctor’s guidance. The verdict on ideal colony count is still out .

Take your probiotic with a meal. This raises the pH in your stomach, which means more bacteria will make it through to your gut, including the few non-acid-resistant strains like S. Thermophilus. And take them with plenty of water; that will further dilute the acidity of gastric juices.

Get your prebiotics in. There are tons of the simple carbs 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, consider taking a prebiotic supplement, usually a powder or drink mix. (Dr. Perlmutter recommends acacia gum.)

Keep up your probiotic routine. 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.