Refrigerated Probiotics

Do Probiotics Need To Be Refrigerated After Opening?

Probiotics, or live bacteria in your gut, may be purchased as supplements, and some should be kept refrigerated and away from direct sunlight. Many probiotic bacteria provide health benefits but are heat and moisture sensitive by nature. Heat kills organisms, whereas moisture activates them inside the pills, only to die due to a lack of nutrition and a suitable environment. 

However, freeze-dried probiotics (primarily available as tablets or pills) in moisture-resistant packaging such as blister packs do not require refrigeration. Still, they should not be exposed to heat above room temperature. They also have a longer shelf life than live culture foods like yogurts and probiotic beverages, which must be refrigerated. Refrigeration is not required for probiotic yeast and some spore-forming bacteria, such as Bacillus coagulans. 


Are Probiotics Okay if Left Out of Fridge?

It depends; while some probiotic strains are shelf-stable, others may need to be refrigerated to extend their life. According to Terpou et al., as published in the Nutrients journal, other strains, such as those belonging to the Bacillus genus, are more resistant to harsh environmental influences and are thought to be more stable. Several manufacturers advocate keeping certain types of probiotics refrigerated rather than storing them at room temperature, as this can help keep the bacteria alive longer. Furthermore, many probiotic-containing foods, such as yogurt and kefir, can deteriorate if not refrigerated. 


Are Refrigerated Probiotics Better?

Refrigerated probiotics are not necessarily better than shelf-stable alternatives. What’s more important is to make sure you buy a high-quality probiotic and store it according to the manufacturer’s recommendations. If your probiotic requires refrigeration, keeping it cold will help maintain the live, active bacteria. It is unnecessary to store probiotics in the refrigerator if it is shelf-stable, but correct storage procedures can increase the likelihood that the bacteria will survive until the expiration date.


How Can I Tell if My Probiotics Are Alive?

The bacteria in a supplement must be “viable,” a scientific term that indicates the probiotics are alive and active, for you to reap the advantages. Laboratory testing and the popular at-home milk test are the two most used methods for determining probiotic viability.

Microbiological Lab Testing

Colony Forming Unit (CFU) is a measurement used by microbiological lab testing laboratories to assess the potency of a probiotic product. Laboratories employ three main approaches to determine the viability of probiotics.

  • Selective Enumeration  

    This is the first step where organisms are inspected to see if they are alive and sufficient in numbers using selective enumeration. Microbiologists detect the probiotic organism(s) present in a product and count the colony-forming units (CFU).

  • Species Information

    Laboratories use culture morphology and DNA sequencing tools to assure product quality in species definition. They can confirm the presence of specific target probiotic bacteria using these methods.

  • Demonstrate Survivability

    Revealing survivability requires monitoring the probiotic microorganism’s survival to determine its viability. This happens throughout a product’s intended shelf life and in various storage situations.

Milk Test

The milk test is a standard at-home method for determining the viability of probiotics. You’ll need 4 oz of chilled milk and the probiotic supplement to complete the test. Allow the milk and probiotic to sit at room temperature for a day or two. Then check it for clump development. If the milk curdles or has a yogurt-like consistency, it proves that the probiotic product is viable.

When the liquid in the milk test gets acidic, clumps form because microorganisms that may digest lactose into lactic acid are present. Lactobacillus is the most common genus of probiotic bacteria that can convert lactose to lactic acid. The higher the amount of lactic acid in the milk, the more clumps it develops.

However, not all probiotic bacteria produce curdling in milk. The Bifidobacterium probiotic family, for example, usually fails the milk test because its habitat requires only a small amount of oxygen to turn milk acidic. 

While this procedure is simple to perform at home, advises that it is not a reliable way to determine the viability of a probiotic supplement, even if the milk curdles immediately. 

Reasons why the probiotic milk test is unreliable include the following:

  1. Certain strains, such as Saccharomyces boulardii, Streptococcus thermophilus, and Lactobacillus bulgaricus, do not cause milk curdling.
  2. The supplement contains chymosin (sometimes referred to as rennin), which is a common enzyme utilized in cheese manufacture. It can also cause milk to curdle; however, rather than producing lactic acid and fermenting the milk, the mechanisms of chymosin work directly on the proteins in milk.
  3. The milk test is also unreliable when using uncrushed probiotic pills or tablets. Putting whole tablets in milk would have no effect, as the probiotics would not make it out into the milk.


What Are Active Probiotics?

Active probiotics are live microorganisms that can provide health benefits when consumed. These beneficial bacteria can help improve gut health, boost immunity, and even help with weight loss. Probiotics are found in many foods, including yogurt, sauerkraut, kimchi, miso, and kefir. You can also find them in supplements. Probiotic supplements should be refrigerated to ensure the live cultures remain viable.


Do Metagenics Probiotics Need To Be Refrigerated?

Even though refrigeration is not required, Metagenics keeps its probiotics refrigerated during manufacturing, warehouse storage, and delivery using frozen gel packs. This is done to protect the product from temperature fluctuations and increase the power of the bacterial strains over time. 



  1. Do Probiotic Pills & Other Supplements Require refrigeration? | (2022). Retrieved 23 April 2022, from 
  2. Terpou, A., Papadaki, A., Lappa, I., Kachrimanidou, V., Bosnea, L., & Kopsahelis, N. (2019). Probiotics in Food Systems: Significance and Emerging Strategies Towards Improved Viability and Delivery of Enhanced Beneficial Value. Nutrients, 11(7), 1591. doi: 10.3390/nu11071591
  3. Probiotic “Milk Test” – Is it Effective in Testing the Quality of the Bacteria in Probiotics? | (2022). Retrieved 23 April 2022, from 


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