The 6 Best Probiotics of 2021, According to a Dietitian

And how to choose the right ones, from third-party testing to strains and CFUs

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Best Probiotics


Our Top Picks
Free of milk, dairy, wheat, and gluten, its usage of lactobacillus rhamnosus helps manage abdominal pain and allergic reactions.
It features L. reuteri and L. fermentum bacteria, which are both known to support vaginal health and immunity.
Designed to boost gut health in light of aging, it contains a bifidobacterium and lactobacterium blend to restore balance.
Grown on a dairy-free medium and free of the top eight allergens, each capsule contains 12 varieties of probiotics.
An ideal choice if you're particularly worried about microbiome disrupters, it's tested for over 125 different pesticides.
The all-in-one pick contains both probiotics and prebiotics to help boost the efficacy of beneficial bacteria.

Probiotics, aka the “friendly bacteria,” are living microorganisms that thrive in our body and work to keep us healthy. Although foods like yogurt contain a decent dose of probiotics, many people turn to supplements for optimal health. Evidence suggests that probiotics may improve digestive health, boost the immune system, and prevent cancer.

With endless rows of products, all containing different species and strains, finding the best probiotic supplement to fit your needs can be a real challenge, and that’s where our experts come in. “It’s important to make sure you’re buying a probiotic that contains the strains your body needs and in the right quantities. Follow your health care provider’s advice about what strains are right for you and aim for a minimum of 5 billion CVUs (colony forming units),” says Lauren Manaker, MS, RDN, LDN, CLEC, CPT, a registered dietitian with her own practice.

According to Manaker, probiotic supplements should be third-party verified to ensure that you are actually getting what you’re looking for. "And since heat can cause damage to live probiotics, it is important to note whether your probiotics are stored in an appropriate temperature," Manaker says.

Our experts unpacked all the research, reviewed the different brands, and compiled a list of their top picks for probiotic supplements, so you don’t have to.

What to Look for in a Probiotic Supplement

Strains and CFUs:

When purchasing a probiotic supplement, check the label for the type of genus, species, and strain to make sure they align with your specific health needs. Look for language that indicates there are live and active bacterial cultures. Locate the amount of CFUs (colony forming units), which are the number of live and active microorganisms in each serving.

For overall health, choose a probiotic with multiple strains. In general, the most common strains come from two species: Lactobacillus and Bifidobacterium. If you have questions about the strain or the number of CFUs to take, talk with your doctor or a registered dietitian about the best probiotic supplement for you.

Third-Party Testing:

Ideally, you should use a probiotic supplement from a reputable brand that goes through third-party testing to evaluate the purity, potency, composition, and other criteria.


Some probiotics require refrigeration. Always look at the product packaging to see whether or not the probiotic needs to be stored in the refrigerator. If you travel frequently or prefer to store your supplements at room temperature, choose a product that does not require refrigeration.

How We Select Supplements

Our team works hard to be transparent about why we recommend certain supplements; you can read more about our dietary supplement methodology here

Here, the best probiotics:

  • Allergy-friendly

  • Helps with diarrhea, gas, and bloating

  • For adults and kids

  • Cannot mix with hot food or drinks

Lactobacillus rhamnosus (LGG) has been used in multiple clinical trials focusing on abdominal pain, infection-induced diarrhea, and allergic reactions such as eczema. Culturelle contains ten billion CFUs (colony forming units) of this evidence-backed bacteria strain per serving.

The independent product testing company, Consumer Labs, confirmed that it contains the listed amount of probiotic organisms and is free of contamination as well as yeast, milk, dairy, wheat, gluten, and lactose, which makes this a great option for anyone who may be following a gut healing-specific diet or looking for an extra gut health boost.

Key nutrients: probiotics, inulin | CFUs, strains: Lactobacillus rhamnosus (LGG) | Storage: Cool, dry place away from direct sunlight. No refrigeration required. | Vegan: Yes | Gluten-free: Yes | Non-GMO: Yes | Organic: No | Additives: None

Garden of Life RAW Probiotics Women

  • Supports vaginal health and immunity

  • Allergy-friendly

  • Can be taken with or without food

  • Must be refrigerated for best results

When taking a probiotic, it’s critical to consume prebiotics in order to support the efficacy of the probiotic. Prebiotics help feed probiotics and help them flourish. They are found in foods such as asparagus, onions, Jerusalem artichoke, and garlic. They are also extracted from other foods and added to probiotics for a one-two punch.

Garden of Life’s One Daily Probiotic for Women contains 33 probiotic strains and 85 billion CFUs. It also supports the efficacy of the beneficial bacteria by adding a prebiotic fiber blend from organic potato and organic acacia fiber. Specific to this product are L. reuteri and L. fermentum bacteria, which are known to support vaginal health and immunity.

Key nutrients: probiotics, prebiotics, vitamin B12, vitamin D | CFUs, strains:: L. reuteri, L. rhamnosus, Lactobacillus bulgaricus, Lactobacillus acidophilus, Bifidobacterium, and more | Storage: Best if refrigerated. Store in a dry place at 71° F (22° C) or below | Vegan: No | Gluten-free: Yes | Non-GMO: Yes | Organic: No | Additives: None

Renew Life Ultimate Flora Probiotic Capsules

  • Restores digestive balance

  • Delayed-release capsules

  • Guaranteed potency through expiration

  • Allergy-friendly

  • Must be refrigerated for best results

Bifidobacterium is a family of microbes that have been shown to be beneficial to gut health, which is important throughout the lifespan. Unfortunately, as humans age, levels tend to decrease.

Renew Life’s Ultimate Flora Adult 50+ Probiotic is designed with this issue in mind. Containing 18 billion CFUs of a special bifidobacterium blend and 18 billion CFUs of lactobacterium blend, this probiotic is intended to restore digestive balance, improve immunity, and promote regularity.

Ensuring quality and potency through expiration, Renew Life’s capsules are delayed-release, which helps the contents make it past the stomach's acidic environment. 

Key nutrients: probiotics | CFUs, strains: Bifidobacterium bifidum, Lactobacillus rhamnosus, Lactobacillus acidophilus, and more | Storage: Best if refrigerated. Store at 77° F (25° C) or below | Vegan: No | Gluten-free: Yes | Non-GMO: Yes | Organic: No | Additives: None

Klaire Labs Ther-Biotic Complete Probiotic

  • Allergy-friendly

  • Can remain potent with heat contact

  • For adults and kids

  • Must be taken with food

Anyone who struggles with allergies knows how tricky it can be to find a supplement that is free of allergens. Klaire Labs grows its probiotics on a dairy-free medium and ensures that their Ther-biotic Complete Probiotic is free of the top eight allergens.

According to Klaire Labs, the company checks its product for potency and guarantees that heat contact from shipping will not disrupt potency. Each capsule contains 12 varieties of probiotics for a total of 25 billion CFU.

Key nutrients:: probiotics, L-leucine | CFUs, strains: Lactobacillus rhamnosus, Bifidobacterium bifidum, Lactobacillus acidophilus, and more | Storage:  Keep refrigerated | Vegan: No | Gluten-free: Yes | Non-GMO: No | Organic: No | Additives: None

Good to Know

When looking for a probiotic, it’s important that potency is guaranteed through expiration. Avoid labels that read “potency guaranteed at the time of manufacture.” The latter statement means that though a probiotic may have 30 billion CFUs in the lab, they cannot guarantee that there will still be 30 billion CFUs when the product hits the shelf. 

INNATE Response Formulas Probiotic Capsules

  • Glyphosate residue-free

  • Vegetarian- and vegan-friendly

  • Allergy-friendly

  • Must be refrigerated for best results

INNATE Response is one of the first supplement companies to guarantee that their products are glyphosate residue-free. This helps to increase the efficacy of their potent Flora 20-14 Probiotic (20 billion CFU, 14 probiotic strains) by limiting interference from a known microbiome disrupter.

Glyphosate, a key ingredient in the weed killer Roundup, has been making headlines recently due to its negative effects on hormones, gastrointestinal health, respiratory health, and immune functioning, among other concerns. In addition to glyphosate, each batch of incoming ingredients is tested for over 125 different pesticides and herbicides. 

Key nutrients:: probiotics, L-leucine | CFUs, strains: Lactobacillus rhamnosus, Bifidobacterium bifidum, Lactobacillus acidophilus, and more | Storage: Keep refrigerated or frozen | Vegan: Yes | Gluten-free: Yes | Non-GMO: Yes | Organic: No but certified glyphosate residue-free | Additives: None

Dr. Ohhira's Probiotics, Original Formula

  • Shelf-stable

  • Allergy-friendly

  • Can be taken with or without food

  • Not vegan-friendly

Selecting a probiotic that contains both pre and post-biotics may improve the efficacy of the beneficial bacteria. Dr. Ohhira's Probiotics contain 12 strains of probiotics, plus natural prebiotics and probiotics. Prebiotics in the non-GMO supplements include ingredients such as prunes, goji berries, and various types of seaweed.

Postbiotics, or beneficial nutrients developed during the fermentation process, include short-chain fatty acids, polyphenols, and oligosaccharides. The unique capsules contain 900 million CFU of lactic acid bacteria. Dr. Ohhira recommends taking one capsule twice daily, about an hour before or after meals.

Key nutrients: prebiotics, probiotics, post-biotics (short-chain fatty acids, vitamins, amino acids) | CFUs, strains: Bifidobacteria, Enterococcus faecalis TH10, Lactobacilli, Streptococcus thermophilus | Storage: Refrigeration not required | Vegan: No | Gluten-free: Yes | Non-GMO: Yes | Organic: No | Additives: None

Final Verdict

While there are many excellent options for probiotics, Culturelle (view at Amazon) is a great, budget-friendly choice that is widely available and offers a potent probiotic boost.


How many CFUs should my probiotic contain?

Probiotic supplements contain a variety of Colony Forming Units (CFUs) or the amounts of viable beneficial bacteria cells. The amount of CFUs in an individual dose can range anywhere from 1 to 10 billion, and even up to 50 billion CFUs or more.

A higher amount of CFUs isn't necessarily better. Labeling laws only require manufacturers to list the total amount of microorganisms, including both live and dead microorganisms. Because only live probiotic microorganisms can benefit your health, be sure to look for products that identify the number of CFU at the end of the product's shelf life instead of the time of manufacture.

Which species of bacteria is most beneficial?

Different probiotics work in different ways. Probiotics can have nonspecific health effects, as well as species and strain-specific mechanisms. Species-specific mechanisms are much more common than strain-specific mechanisms. For example, the rhamnosus species, of which the most commonly known is Lactobacillus, may help eliminate infectious diarrhea, whereas some strains of the Bifidobacterium species may reduce IBS symptoms.

Overall, it's best to look for a probiotic with various species that can promote multiple beneficial effects.

What Experts Say

“Probiotics can fight infections, boost immunity, and assist with digestion and regularity. If you are taking probiotics for general wellness, I recommend starting with 20 to 50 billion CFU and purchasing probiotics sold in the refrigerated section of the store. Since probiotics are live bacteria, they should be kept in a cool environment to prevent expiration.”—Amy Shapiro, MS, RD, CDN

Why Trust Verywell Fit?

As a Registered Dietitian, Sydney Greene takes supplement recommendations seriously. Every product has been researched and vetted by her against clinical research, product reviews, and third-party testing websites. These are products she would not only feel comfortable recommending to her clients but she would take them herself if needed.

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Article Sources
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