Probiotics Facts & Myths

Did you know your body can contain up to ten times more bacteria than it does human cells? Probiotics are living microorganisms that can have beneficial effects on the microbiome and on many aspects of the human body; their use has become quite widespread in the last several years. But as is common among topics that rapidly rise in popularity, misinformation is easily spread as some companies may prey on customers’ ignorance.

We think it’s time to debunk the most common myths about probiotics so you can make informed decisions.

Myth: All probiotic strains are created equal.

Fact: Only a handful of probiotic strains have been clinically shown to support human health. In fact, only a few probiotic strains have been researched extensively.1

What is a “strain”? While many probiotics are listed as a genus and species (such as Lactobacillus acidophilus), each species can also have many strains, and each strain may have different effects on particular body systems.2 For example, L. rhamnosus GR-1® and L. reuteri RC-14® are two probiotic strains shown to specifically target women’s health.*3

Myth: Better-quality probiotics don’t require temperature-controlled environments.

Fact: Since probiotics are living microorganisms, it makes sense that they must exist in a habitable environment. They are sensitive to heat and moisture, which can impact viability. If handled carelessly or exposed to extremely high temperatures during shipping or storage, these tiny organisms may die off and/or lose their effectiveness, which equals a lack of potency and subsequent lack of health benefits.4

How can probiotics products be protected from heat? Refrigeration is not required for probiotics, but it is often the best way to protect the viability and ensure potency over a longer period of time.4 Reputable manufacturers usually ship probiotic products with ice packs to help ensure they are protected on their journey to you. Although the ice may melt before delivery, the temperature within the package should remain well below the level at which damage to the bacteria could occur.4

Packaging of probiotics is important, as well, to maintain viability. Desiccant packets in product bottles help to reduce moisture from the environment, while the bottles themselves matter too. Look for amber glass bottles, which eliminate the risk of UV oxidation.5

Read: 6 Things to Look for in a Probiotic

Myth: The higher the potency, or total numbers, of a probiotic, the better the results.

Fact: As it is important to utilize well-researched probiotic strains, it’s also important to keep in mind that the research conducted is usually done based on a total number of colony-forming units (CFU) of a specific probiotic. The potency, or total number of CFU, should be based on published scientific and clinical data on specific strains that demonstrate clinical efficacy for particular health benefits.6

In other words, if a study on a specific probiotic strain indicates health benefits at a dosage of 10 billion CFU, any product touting that benefit should have exactly 10 billion CFU. Companies promoting products with a higher number, and therefore a supposed increased benefit, may not be clinically accurate or relevant.

Myth: Guaranteed potency at the time of production and expiration is the same thing.

Fact: While some probiotic manufacturers tout the number of CFU at the time of production, not all can guarantee that you’ll get this number when you take them. Probiotics die over time, and this loss of efficacy can increase depending on manufacturing, shipping, and storage processes.4 Only products that guarantee potency at expiration assure reliable efficacy from start to finish. This follows the Best Practices Guidelines for Probiotics from the Council for Responsible Nutrition (CRN) and the International Probiotics Association.7

Quality probiotics state a guaranteed bacterial number on the label, with instructions for the consumer on  proper usage. With appropriate storage after delivery, potency ideally should be guaranteed through the date of expiration—for reliable efficacy with every use.

For more information on probiotics and nutrition, please visit the Metagenics blog.


  1. National Center for Complementary and Integrative Health. Probiotics: In Depth. US Department of Health and Human Services. Accessed May 3, 2019.
  2. National Institutes of Health. Probiotics. US Department of Health & Human Services. Accessed May 3, 2019.
  3. Köhler GA et al. Infect Dis Obstet Gynecol. 2012;2012:636474.
  4. Govender M  et al.  AAPS PharmSciTech. 2013;15(1):29–43.
  5. Fenster K et al.  Microorganisms. 2019;7(3):83.
  6. Sniffen JC et al. PLoS One. 2018;13(12):e0209205.
  7. Best Practices Guidelines for Probiotics. Council For Responsible Nutrition. Available at: Accessed April 18, 2019.

Submitted by the Metagenics Marketing Team

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