Probiotics are among the most popular of all dietary supplements, and sales continue to skyrocket each year. By 2023, probiotic supplement sales are projected to exceed 64 billion dollars (1).

People may take probiotics because they’ve heard they can help reduce symptoms of certain medical conditions, boost immune health, improve depressive symptoms, and even promote weight loss.

But are probiotics really effective? Should everyone be taking a probiotic?

If you and your healthcare team decide that you may benefit from taking a probiotic supplement, there are many excellent products on the market to choose from.

Depending on your needs, you may want to choose a single or multi-strain probiotic. If you’re unsure about the type of probiotic or dosage that you should be taking, ask your healthcare professional for advice.

We selected the best probiotics using the following criteria:

  • Vetting. All the products have been vetted to ensure that they meet Healthline’s medical and business standards.
  • Effective dose. All of the supplements below contain at least 106 (1 million) colony-forming units (CFUs) per gram.
  • Ingredients. We looked for products that are made from high quality ingredients and free of artificial additives and fillers.
  • Personal needs. Whether you need a specific probiotic strain or follow a gluten-free diet, we included options to suit a variety of needs and preferences.

This article explains what probiotic supplements are, who may benefit from taking one, how to choose the right kind, and our picks of the 6 best products on the market.

Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” (1).

Probiotics are naturally found in certain foods and your gut. For example, foods like kimchi, fermented yogurt, and sauerkraut can be natural sources of probiotics. Probiotics can also be added to foods during processing.

Beneficial bacteria reside in your intestinal tract and participate in a variety of important bodily processes, such as vitamin production, mood regulation, digestion, immune function, and more (2).

Probiotics can also be taken in supplement forms, which contain high doses of a single probiotic strain or multiple probiotic strains.

Among all species of probiotics, Lactobacillus and Bifidobacterium species are by far the most commonly studied and added to probiotic supplements. These species are also the dominant strains in human intestinal tracts (2).

In addition to probiotic bacteria, probiotic yeasts like Saccharomyces cerevisiae (S. cerevisiae) and Saccharomyces boulardii (S. boulardii) can be taken in supplement form.

The seven main groups of probiotics most often used in supplements are Lactobacillus, Enterococcus, Saccharomyces, Bifidobacterium, Streptococcus, Escherichia, and Bacillus (3).

Probiotics are named by their genus, species, and alphanumeric strain designation. They may also have a subspecies. For example, a probiotic may contain a specific strain of Bifidobacterium called Bifidobacterium longum 35624 (B. longum 35624) (3).

Probiotics are measured in colony-forming units or CFUs. These units represent the number of viable bacteria per dose.

Products labeled as 1 x 109 CFU contain 1 billion viable or live bacteria per dose. Most supplements contain 1–10 billion CFUs per dose. However, some supplements contain much higher amounts.

To confer beneficial effects, probiotics must be taken in quite large doses. Researchers suggest that probiotics must contain at least 106 (1,000,000) viable CFUs per gram to be able to survive digestion and exert positive effects in the body (4).

It’s suggested that the minimum recommended effective dose per day is 108–109 cells or 100,000,000–1 billion cells (5).

Interestingly, probiotic manufacturers are only required to list the total weight of the microorganisms in the product on the label, including both live and dead microorganisms.

Because probiotics are quite vulnerable to factors like temperature change and storage time, many may no longer be viable by the time the product is purchased.

For this reason, the National Institutes of Health (NIH) recommends that customers choose products that include CFUs at the end of a product’s shelf life, which indicates that a product contains a therapeutic number of CFUs after the product is purchased (3).

Probiotic supplements have been linked to some health benefits. But while probiotic research has grown exponentially over the past 20 years, researchers are still learning about probiotics and their health effects when taken in supplement form.

Summary

Probiotics are live microorganisms that may benefit health when taken in adequate doses. Probiotic supplements can contain 1 or multiple probiotic strains and usually contain 1–10 billion CFUs per dose.

If you’re interested in taking a probiotic supplement, it’s important to first determine whether a probiotic supplement is necessary for your specific health needs.

If you’re instructed to take a probiotic, please consider the following:

  • Brand. Manufacturing processes, the shelf life, and the formulation type can significantly affect a probiotic supplement’s effectiveness. As such, purchasing probiotics from established, physician-trusted brands is essential (6).
  • Probiotic strains. Probiotics are not one-size-fits-all remedies, and certain probiotic strains are much more effective for certain medical conditions and symptoms than others. Look for supplements with specific strains based on your needs.
  • Intended use. The effectiveness of probiotic supplements is not only strain-specific but also disease-specific, meaning the correct strain and dose must be appropriate for the condition or symptom intended to be treated (6).
  • CFUs. The product quality matters. It’s important to look for probiotics that contain at least 106 (1 million) CFUs per gram, as research suggests that this is the minimum amount needed to exert positive effects in the body (4).
  • Storage requirements. Some probiotics require refrigeration. Check the product label for proper storage instructions. In general, probiotics are sensitive to heat. Thus, if they don’t require refrigeration, you’ll want to store them in a cool, dry area.
Summary

When shopping for probiotic supplements, in addition to purchasing them from a reputable brand, it’s important to consider the probiotic strains, CFU count, storage requirements, and your intended use.

Culturelle Digestive Daily

Price: $$

One capsule of Culturelle Digestive Daily probiotic has 10 billion CFUs of Lactobacillus rhamnosus GG, a probiotic strain that may benefit a number of health conditions like diarrhea and irritable bowel syndrome (IBS), plus 200 mg of the prebiotic inulin, which fuels beneficial gut bacteria (7).

​​Culturelle guarantees that the stated number of CFUs on the box is viable through the expiration date of the product, something the NIH recommends customers look out for.

Culturelle products are packaged to maintain viability, and the company is certified through NSF International, an organization that independently tests supplements for quality and potency and inspects manufacturing facilities.

Culturelle products don’t require refrigeration.

Align Probiotic Extra Strength

Price: $$$

Align is a physician-trusted brand that contains Bifidobacterium longum 35624, formerly known as Bifidobacterium infantis 35624, a probiotic strain that has been researched for its role in digestive health, including IBS symptoms (8).

Align’s Extra Strength probiotic label states that each capsule contains 5 billion live bacteria at the time of manufacturing and 50,000,000 CFUs up until the “best by” date.

As it doesn’t require refrigeration, it’s a good option if you frequently travel or prefer not to worry about storing your probiotic supplement in the fridge.

Note that Align contains trace amounts of lactose, so it may not be appropriate for those with severe lactose intolerance.

Bio-Kult

Price: $

Bio-Kult contains 14 probiotic strains, including Lactobacillus acidophilus, Streptococcus thermophilus, and Bifidobacterium longum.

Each Bio-Kult capsule contains a minimum of 2 billion microorganisms, and Bio-Kult guarantees that the total bacteria count of their products is viable until the end of the product’s shelf life.

Each probiotic strain in Bio-Kult is microencapsulated and individually freeze-dried, which protects the probiotics from stomach acid and allows the product to be stored at room temperature.

Bio-Kult products are third-party tested by United Kingdom Accreditation Service (UKAS) accredited labs.

Bio-Kult is not appropriate for those with a severe allergy to milk proteins, but it is safe for those with lactose intolerance.

Jarrow Formulas Jarro-Dophilus EPS

Price: $

Jarrow Formulas Jaro-Dophilus EPS® contains 8 probiotic species from 6 genera, including, Lactobacillus, Bifidobacterium, Lacticaseibacillus, Lactiplantibacillus, Lactococcus, and Pediococcus.

The capsules have an enteric coating, which is a barrier that helps minimize degradation in the stomach.

Some studies show that enteric-coated probiotics are more effective than nonenteric-coated probiotics. A 2019 study found that enteric coating led to a 20‐ to 40‐fold increase in the delivery of viable probiotics to the small intestine (9).

When stored properly — at room temperature, in a cool, dry environment — the 5-billion-CFU count per capsule is guaranteed within the “best used before” date.

Jarrow Formulas products are tested by third-party labs that are accredited by the United States Department of Agriculture (USDA).

Garden of Life Dr. Formulated Probiotics Once Daily 30 Billion CFUs

Price: $$$

Garden of Life Dr. Formulated Probiotics Once Daily 30 Billion CFUs provides 30 billion CFUs of 14 probiotic strains, including Bifidobacterium lactis, Lactobacillus acidophilus, and Lactobacillus casei.

Garden of Life guarantees the CFU count through the end of the product’s “best use” date when stored properly. This supplement keeps best in the refrigerator.

This product is dairy-free and makes a good choice for those with lactose intolerance.

While it’s also made without peanuts, tree nuts, shellfish, and soy products, the supplement is manufactured in a facility that handles major allergens, so it may not be a good option if you have a severe food allergy.

NOW Probiotic-10 25 Billion

Price: $$

NOW Probiotic-10 25 Billion is a blend of 10 probiotics inducing Lactobacillus acidophilus, Bifidobacterium lactis, and Lactobacillus rhamnosus, many of which have been shown to support immune health (10).

This product is formulated to deliver a potency of at least 25 Billion CFUs through the “best by” date.

NOW uses DNA-fingerprinting technology to guarantee the identity, potency, and purity of the bacterial strains used in its probiotic products. This testing also helps identify potential bacterial contaminants in the products prior to manufacturing.

Additionally, NOW is certified by Underwriters Laboratory, an independent certification safety company that tests products to ensure they meet strict purity and quality standards.

Probiotic supplements have been shown to benefit health in a number of ways.

Yet, some of the purported benefits of probiotics aren’t supported by research, so it’s important to always consult a healthcare professional before taking a probiotic supplement, especially if you’re hoping to improve symptoms related to a health condition.

May improve symptoms of certain gastrointestinal diseases

Some of the most well-studied uses of probiotic supplements relate to the treatment of gastrointestinal diseases like irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD).

One review of 11 studies found that 7 of them reported that probiotic supplementation significantly improved symptoms like bloating and abdominal pain in IBS patients, compared with a placebo, while the remaining 4 studies did not find significant improvements.

The review also found that multi-strain probiotics used for at least 8 weeks seemed to be most effective at improving IBS symptoms (11).

Notably, Lactobacillus acidophilus was present in all of the multi-strain supplement studies that reported significantly improved symptoms (11).

Multi-strain probiotics may improve some symptoms in those with IBD, though they appear to be less effective for people with Crohn’s disease.

Evidence is currently limited, and well-designed studies are needed (12, 13, 14).

May help with constipation and diarrhea

Studies indicate that probiotics may help improve multiple types of diarrhea, including infectious diarrhea, antibiotic-associated diarrhea, and traveler’s diarrhea (15, 16, 17).

Certain strains, including Lactobacillus rhamnosus GG and Saccharomyces boulardii, seem to be effective at treating diarrhea in children and adults (18).

Some probiotics, such as ​​Bifidobacterium lactis, may also help improve constipation. However, study results vary, with some showing no improvements in constipation with probiotic treatment (19).

May benefit urinary health

Supplementing with probiotics may help maintain urinary tract health and be beneficial for women who get frequent urinary tract infections (UTIs) (20).

Some studies have shown that treatment with the probiotics Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 may help reduce UTIs in women (21, 22).

However, study results are conflicting.

One review of three randomized controlled trials found that probiotics did not significantly reduce UTI recurrence in postmenopausal women (23).

Other potential benefits

In addition to the potential benefits listed above, some research suggests that probiotic supplements may have the following effects:

  • May promote immune health. Evidence supports the role of probiotic supplements in maintaining immune health. Some studies have shown that they may enhance immune function in certain populations, but more research is needed (24, 25, 26).
  • May benefit metabolic health and weight management. Alterations in gut bacteria may contribute to obesity and metabolic issues, and some studies have shown that probiotic supplementation may promote weight loss. Research in this area is ongoing (27).
  • May improve cardiovascular risk factors. Probiotic supplementation may help reduce blood lipid levels in some people, which may decrease the risk of heart disease. However, evidence is limited at this time (28, 29, 30).
  • May help treat certain mood and emotional disorders. Studies suggest that certain probiotics may help treat depression, but more high quality studies are needed before strong conclusions can be made (31, 32).
Summary

Probiotics may benefit certain health conditions, including IBS, certain types of IBD, and UTIs. However, their effectiveness depends on many factors, including the strain, dose, and length of treatment.

Contrary to popular belief, probiotic supplements are not necessary or appropriate for most people.

Not only can they be expensive, but they may lead to side effects like bloating and bacterial overgrowth. Plus, they could lead to excessive immune stimulation and infection among people with weakened immune systems (33, 34).

While some people, including those with IBS and certain types of IBD, may benefit from specific strains of probiotics, in general, most healthy people who follow a nutritious diet and healthy lifestyle do not need to supplement with probiotics.

Plus, some researchers are concerned that the widespread use of probiotics may lead to antibiotic resistance and warn that many studies investigating the safety and efficacy of probiotics are of poor quality (35).

For these reasons, it’s not a good idea to take probiotics before consulting a healthcare professional. They can help you decide whether a probiotic supplement is appropriate and give brand and dosage recommendations.

Summary

Even though probiotics are widely used and prescribed, they’re not appropriate for everyone. Speak with a healthcare professional if you’re interested in taking a probiotic supplement.

Probiotics supplements may help those with certain conditions like IBS, constipation, and urinary tract infections.

However, probiotics aren’t necessary for everyone, and the effectiveness of probiotic supplements depends on the strain, dosage, and condition being treated.

Note that probiotics are not one-size-fits-all remedies, and it’s best to work with a healthcare professional to determine whether a probiotic supplement is the right choice for your health needs.

If you could benefit from a probiotic, they can help you choose the right strain or strains of probiotics, as well as a suggested daily dose depending on your medical history and symptoms.

Finally, there are many other ways to take care of your digestive and overall health that don’t involve dietary supplements.

Following a nutrient-dense diet, managing your stress levels, getting enough sleep and exercise, and maintaining a healthy body weight are much more important for your health than taking any one supplement.