How to Choose a Good Probiotic

Probiotics vary drastically in cost, quality, and effectiveness. While the supplement industry is booming, consumers and health professionals are confused about how to make confident decisions about which supplements to buy and recommend. One of the supplements that is often asked about is a probiotic supplement. Balancing the importance of the number of strains, the number of colony-forming units (CFUs), which strains are included, and price can leave your head (and your gut) spinning. This article will give you some guidance for reviewing your current probiotic or finding the right one for yourself or your clients.

What are probiotics?

Probiotics are beneficial bacteria found in food or supplements. They can promote the health and population of the bacteria living in the intestines.

Your gut is home to over 4 trillion microbes. Many of these microbes support a variety of physical processes that are important for maintaining health and wellness. The microbes that support health are considered beneficial, but our dietary, lifestyle, and supplement choices can also support these microbes. Simply taking a probiotic won’t fix a health problem; you must also include the other gut-healthy habits.

Seven Steps for Choosing and Recommending a Good Probiotic:

1. Find a probiotic with at least 20 billion CFUs.

Most probiotics contain between 1 billion and 10 billion colony forming units (CFUs), and some contain up to 60 billion CFUs. That said, a high CFU is not always better.1

Although a higher CFU count is usually a good indicator, it does not need to include the upper end of 60 billion CFUs. A probiotic with 20–30 billion CFUs is a great place to start and has shown to be equally beneficial if a good variety of strains is included.1 Ixcela Biome Support includes 30 billion CFUs.

It's not just about CFU's. You are going to want to follow the next five steps before making your selection.

2. Make sure your probiotic contains at least 15 different strains.

You rarely want to take a single-strain probiotic unless you are directed to do so by a physician. A single-strain probiotic is not going to be as effective as a multi-strain probiotic and could actually skew the gut microbiome toward one type of bacteria, which could lead to a dysbiosis (bacterial imbalance).2 Similar to CFUs, research does not support a certain number of strains of bacteria to be beneficial. Multi-strain probiotics will include two or more strains of bacteria, but two strains aren’t enough. We recommend looking for a probiotic that contains at least 15 different strains of bacteria.

Ixcela Biome Support includes 17 different strains of beneficial bacteria.

3. Determine if the strains are actually beneficial.

This step is complicated. Because researching a long list of bacterial strains is not something that most people feel comfortable with (or have time for), it is challenging to figure out if the strains included are actually beneficial. We’ve tried to make it a little easier by including a list of strains that research has shown to support a variety of health conditions. Use the list below and compare and contrast the probiotic you are currently taking or interested in. How does it compare to the list below?

  1. Bifidobacterium bifidum (B. bifidum) supports blood sugar.3
  2. Bifidobacterium breve (B. breve) supports intestinal health, especially if you’ve taken antibiotics. Studies have found that many digestive problems coincide with low levels of B. breve.4
  3. Bifidobacterium lactis (B. lactis) supports inflammatory response and allergies.5
  4. Bifidobacterium infantis (B. infantis) supports digestion and can help to alleviate bloating, digestive discomfort, and constipation.5
  5. Bifidobacterium longum (B. longum) helps maintain the integrity of the gut wall and supports the immune system.6
  6. Lactobacillus acidophilus (L. acidophilus) supports digestion and immune response.6,7
  7. Lactobacillus brevis (L. brevis) supports immune response and inflammation.8
  8. Lactobacillus bulgaricus (L. bulgaricus) supports skin health and can help to stimulate growth of other beneficial bacteria.9,10
  9. Lactobacillus casei (L. casei) supports immune response and serotonin production.11,12
  10. Lactobacillus helveticus (L. helveticus) helps to reduce invasion of bacteria that cause infectious disease.13
  11. Lactobacillus paracasei (L. paracasei) may be helpful for individuals with symptoms of leaky gut and helps fight cavities in teeth.14,15
  12. Lactobacillus plantarum (L. plantarum) supports inflammatory response.5
  13. Lactobacillus rhamnosus (L. rhamnosus) supports the immune system and may support cholesterol levels.16,17
  14. Lactobacillus salivarius (L. salivarius) supports the immune system and gut health by maintaining a healthy environment for other beneficial bacteria to thrive.5,18
  15. Lactobacillus gasseri (L. gasseri) has been reported to support digestion and balanced blood sugar.19,20
  16. Lactobacillus lactis (L. lactis) encourages a normal gut environment and has an anti-inflammatory effect.21
  17. Streptococcus thermophilus (S. thermophilus) supports skin health and the immune system.22,23

4. Check that it will make it past the stomach.

When you hear “gut health,” you might picture your stomach, but a healthy stomach is far too acidic to be colonized by microbes. This is the same for probiotics. If they are exposed to the acidic environment of the stomach, the living probiotics will be killed before they even have a chance to do their job in the lower gut. To ensure that your probiotic will actually make it to where it needs to be, check the label to ensure it has an enteric capsule. An enteric capsule will protect the probiotic strains as they pass through the more acidic regions of the stomach and gut and make their way to the lower small intestine and large intestine, or colon.

5. Find out what the other ingredients are.

Supplements will always contain a variety of other ingredients to ensure the pill is shelf-stable, will not fall apart, doesn’t absorb moisture, etc. While it is nearly impossible to avoid all added ingredients in the “other ingredients” list, it is important to review this list to make sure it does not include ingredients that could compromise you or the probiotic.

First, if you have a food allergy, intolerance, or sensitivity, make sure that the probiotic supplement does not include any derivatives from that food. Corn, wheat, soy, and dairy are the common ones to look out for. See our label below for examples of ingredients that are included and excluded.

While looking for ingredients that you want to avoid, also review the label for ingredients you want to include. For example, prebiotics. Prebiotics are dietary fibers that are indigestible to humans but help to promote the growth of beneficial bacteria living in the gut. Look for probiotics that include both a pre- and pro- biotic.

If you are following a low FODMAP diet or have experienced severe discomfort from probiotics in the past, review the label of the probiotics you took in the past to see if they contained prebiotic fibers. If so, the prebiotics might be to blame for the discomfort. Work with a physician, dietitian, or healthcare provider to find a probiotic that will work well for you.

6. Check the expiration date and date of manufacture.

This might seem obvious, but it is often overlooked for supplements and especially probiotics. Remember, probiotics contain live bacterial strains and are therefore fragile. It is important to first check the expiration date and the use-by date on the bottle. Then, review the directions for storage. Although most probiotics are shelf-stable, if the bottle directs you to keep it in the fridge, we recommend doing so. It will never hurt, and it will only help to ensure shelf life.

If you want to check to see if the bacteria included in a probiotic are still alive, try this test.24

  1. Split two probiotic capsules and pour contents into a half cup of milk. 

  2. Let it sit on the counter for 48 hours and assess for consistency. 

  3. If the probiotics are alive, they should turn the milk into a pudding- or yogurt-like consistency.

Check out this video for support:

7. Assess your need for a probiotic. 

A multi-strain probiotic supplement is safe for most people to take, but there are a few cases where it is not a good idea to take probiotics. First, you should never start a supplement without consulting a doctor, dietitian, or trusted health professional.

Second, individuals with any sort of immune deficiency or who are being treated for cancer should never use probiotics.25 As research continues to unfold about the benefits of probiotics, it is important to remember that you can also support the health of the gut microbiome by including a variety of nutrient-dense, plant-based foods and low-sugar fermented foods to support the gut microbiome in place of a probiotic supplement. If you find that you are struggling with one of the symptoms or conditions listed with a strain of probiotic above, consider taking a multi-strain probiotic that could help to alleviate your symptoms.

Finally, test your gut health and function with the Ixcela test. The Ixcela test will review markers in the blood that will help to guide you to determine if you should consider a probiotic and other dietary and lifestyle changes that will support your gut microbiome.

About the Author

Photo: Rachel Stuck, RDN

Registered Dietitian Nutritionist Rachel Stuck has a background in culinary arts and nutrition counseling. Rachel takes a positive approach to nutrition: she avoids recommending restrictive diets and instead focuses on helping people choose foods that promote health and well-being. She is passionate about empowering and assisting Ixcela members as they develop their unique, gut-healthy lifestyles.

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Interested in learning more about Ixcela? Check out Ixcela’s microbiome test, personalized nutrition and fitness plans, and other tools to help you optimize your health.


1. “Office of Dietary Supplements - Probiotics.” NIH Office of Dietary Supplements, U.S. Department of Health and Human Services,

2. Timmerman , H M, et al. “Monostrain, Multistrain and Multispecies Probiotics--A Comparison of Functionality and Efficacy.” International Journal of Food Microbiology, U.S. National Library of Medicine, 15 Nov. 2004,

3. Gomes, Aline Corado, et al. “Gut Microbiota, Probiotics and Diabetes.” Nutrition Journal, BioMed Central, 17 June 2014,

4. “Bifidobacterium Breve.” Bifidobacterium Breve - an Overview | ScienceDirect Topics, 2018,

5. Smelt, Maaike J, et al. “L. Plantarum, L. Salivarius, and L. Lactis Attenuate Th2 Responses and Increase Treg Frequencies in Healthy Mice in a Strain Dependent Manner.” PloS One, U.S. National Library of Medicine, 9 Oct. 2012,

6. Akatsu, Hiroyasu, et al. “Clinical Effects of Probiotic Bifidobacterium Longum BB536 on Immune Function and Intestinal Microbiota in Elderly Patients Receiving Enteral Tube Feeding.” JPEN. Journal of Parenteral and Enteral Nutrition, U.S. National Library of Medicine, Sept. 2013,

7. Perdigón, G., et al. “Interaction of Lactic Acid Bacteria with the Gut Immune System.” Nature News, Nature Publishing Group, 13 Jan. 2003,

8. “Lactobacillus Brevis.” Lactobacillus Brevis - an Overview | ScienceDirect Topics, 2018,

9. “Lactobacillus Delbrueckii Subsp. Bulgaricus.” Lactobacillus Delbrueckii Subsp. Bulgaricus - an Overview | ScienceDirect Topics, 2013,

10. Roberts, Sue. “Lactobacillus Bulgaricus Benefits.” Healthy Eating | SF Gate, 27 Dec. 2018,

11. Galdeano, C. Maldonado, and G. Perdigón. “The Probiotic Bacterium Lactobacillus Casei Induces Activation of the Gut Mucosal Immune System through Innate Immunity.” Clinical and Vaccine Immunology : CVI, American Society for Microbiology, Feb. 2006,

12. Cheng, Li-Hao, et al. “Psychobiotics in Mental Health, Neurodegenerative and Neurodevelopmental Disorders.” Journal of Food and Drug Analysis, No Longer Published by Elsevier, 10 Feb. 2019,

13. Eytan, et al. “Strain-Specific Probiotic ( Lactobacillus Helveticus ) Inhibition of Campylobacter Jejuni Invasion of Human Intestinal Epithelial Cells.” OUP Academic, Oxford University Press, 1 Nov. 2009,

14. Wake Forest Baptist Medical Center. “Dead Probiotic Strain Shown to Reduce Harmful, Aging-Related Inflammation.” ScienceDaily, ScienceDaily, 9 Dec. 2019,

15. Teanpaisan, Rawee, et al. “Effect of Long-Term Consumption of Lactobacillus Paracasei SD1 on Reducing Mutans Streptococci and Caries Risk: A Randomized Placebo-Controlled Trial.” Dentistry Journal, MDPI, 1 Apr. 2015,

16. Villena, Julio, et al. “Orally Administered Lactobacillus Rhamnosus Modulates the Respiratory Immune Response Triggered by the Viral Pathogen-Associated Molecular Pattern Poly(I:C).” BMC Immunology, BioMed Central, 18 Sept. 2012,

17. Yoon, Hong-Sup, et al. “Lactobacillus Rhamnosus BFE 5264 and Lactobacillus Plantarum NR74 Promote Cholesterol Excretion Through the Up-Regulation of ABCG5/8 in Caco-2 Cells.” Probiotics and Antimicrobial Proteins, U.S. National Library of Medicine, Dec. 2011,

18. “Lactobacillus Salivarius.” Lactobacillus Salivarius - an Overview | ScienceDirect Topics, 2010,

19. Koga, Yasuhiro, et al. “Probiotic L. Gasseri Strain (LG21) for the Upper Gastrointestinal Tract Acting through Improvement of Indigenous Microbiota.” BMJ Open Gastroenterology, BMJ Publishing Group, 12 Aug. 2019,

20. Yun, S.I., Park, H.O., Kang, J.H. “Effect of Lactobacillus Gasseri BNR17 on Blood Glucose Levels and Body Weight in a Mouse Model of Type 2 Diabetes.” Journal of Applied Microbiology, U.S. National Library of Medicine, Nov. 2009,

21. Diniz Luerce, Tessalia, et al. “Anti-Inflammatory Effects of Lactococcus Lactis NCDO 2118 during the Remission Period of Chemically Induced Colitis.” Gut Pathogens, BioMed Central, 29 Jul. 2014,

22. Talakoub, Lily and Naissan O. Wesley. “Probiotic, Prebiotic, and Postbiotic Skin Care.” MDedge Dermatology, 13 Feb. 2019,

23. Perdigon, G., et al. “Enhancement of Immune Response in Mice Fed With Streptococcus Thermophilus and Lactobacillus Acidophilus.” Journal of Dairy Science, U.S. National Library of Medicine, 1987,

24. Vital Updates. Probiotic Milk Test Could Reveal Effectiveness. Vital Update, 2017,

25. Harvard Health Publishing. “Should You Take Probiotics?” Harvard Health, Apr. 2015,