The 6 Best Probiotics of 2021, According to a Dietitian

How to choose a probiotic that is right for you

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Best Probiotics

Verywell / Sabrina Jiang

Probiotics, aka the “friendly bacteria,” are living microorganisms that thrive in our body and work to keep us healthy. Although foods like yogurt and other fermented foods 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.

Probiotic Dosage

Always speak with a health care professional before adding a supplement to your routine to ensure that the supplement is appropriate for your individual needs and which dosage to take.

There is not an established RDA (Recommended Daily Allowance) for probiotics. Probiotic supplements typically range from 1 to 10 billion CFUs, while some contain up to 50 billion CFUs. According to the NIH, higher CFUs do not necessarily correlate to improved effectiveness and better health outcomes. 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.

Consider the amount of probiotics you are getting from food and supplement accordingly. For example, if yogurt is a staple in your diet, you may opt for a lower dosage of probiotics. Once you have selected a probiotic supplement, follow the recommended dosage the brand outlines for the specific product you are using, as all probiotic supplements differ.

Frequently Asked Questions

  • 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.

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

We support supplements that are evidence-based and rooted in science, as well as clinically tested and approved for use in humans. We value certain product attributes that we find to be associated with the highest quality products. These attributes include non-GMO, Organic, and allergy-friendly products that are free of most artificial ingredients including colors, flavors, preservatives, and sweeteners. When possible, we recommend products that are third-party tested and certified.

It's important to note that the FDA does not review dietary supplements for safety and effectiveness before they go to market. Our team of experts has created a detailed, science-backed methodology to choose the supplements we recommend.

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

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

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

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

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

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.

If you're looking for a synbiotic, try Dr. Ohhira's Probiotics (view at Amazon), containing 12 strains of probiotics, plus natural prebiotics.

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10 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kechagia M, Basoulis D, Konstantopoulou S, et al. Health benefits of probiotics: a reviewISRN Nutrition. 2013;2013:1-7. doi:10.5402/2013/481651

  2. National Institutes of Health. Office of Dietary Supplements. Probiotics. Fact sheet for health professionals. Updated June 3, 2020.

  3. NIH Office of dietary supplements - probiotics.

  4. National Institutes of Health. Office of Dietary Supplements. Probiotics. Fact sheet for health professionals. Updated June 3, 2020.

  5. U.S. Food & Drug Administration. Questions and Answers on Dietary Supplements. Updated July 22, 2019.

  6. Capurso L. Thirty Years of Lactobacillus rhamnosus GG: A Review. J Clin Gastroenterol. 2019;53 Suppl 1:S1–S41. doi:10.1097/MCG.0000000000001170

  7. Markowiak P, Śliżewska K. Effects of probiotics, prebiotics, and synbiotics on human healthNutrients. 2017;9(9):1021. doi:10.3390/nu9091021

  8. Kato K, Odamaki T, Mitsuyama E, Sugahara H, Xiao JZ, Osawa R. Age-related changes in the composition of gut Bifidobacterium speciesCurr Microbiol. 2017;74(8):987–995. doi:10.1007/s00284-017-1272-4

  9. Klaire Labs. About Probiotics.

  10. Samsel A, Seneff S. Glyphosate, pathways to modern diseases II: Celiac sprue and gluten intoleranceInterdiscip Toxicol. 2013;6(4):159–184. doi:10.2478/intox-2013-0026