Many people keep probiotic supplements in the refrigerator, often wedged between bottles of kombucha and cartons of yogurt. But it can get crowded. Could probiotic supplements be stored in a cupboard near vitamins and fish oil capsules?
In other words, do probiotic supplements require refrigeration?
As “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host,” probiotics when delivered via supplements are produced within protocols to help the organisms survive in sufficient numbers that match a specific clinical end need.
Although bacteria viability may not always be mandatory for beneficial clinical effects (as recent research with heat-treated probiotic cells demonstrates) keeping the microorganisms alive until consumption has been the traditional goal.
The viability of the microbes depends on a long list of factors. These include processing temperature, pH of the matrix material, oxygen level in the product, presence of other competing bacteria, and toxicity of metabolites. During transport and storage, the temperature and moisture content of the products are major factors to be considered.
“In general, high temperature importantly decreases microorganism’s viability while low temperature, like refrigeration, has been reported to be better for the survival of certain probiotics,” asserted researchers in a 2020 review.
Probiotics, therefore, require special care at every stage of manufacturing, transport and storage. Fortunately, responsible producers consider all these variables when they assure that the number of colony-forming units (CFUs) listed on their labels is actually present at the end of the product’s shelf life.
In the past few decades, manufacturers have made great strides in protecting the viability of probiotic supplements.
A 2021 review titled Targeted Delivery of Probiotics: Perspectives on Research and Commercialization described the challenges and technologies that have been adopted for industrial applicability. Foremost is the encapsulation of probiotics, which helps maintain the potential of probiotics throughout shelf life. In essence, a protective matrix walls off the live probiotics from adverse conditions. If unprotected (non-encapsulated probiotics), high temperatures — along with other adverse conditions including high operational pressures, shear stresses, and low gastric pH — may result in the depletion of probiotic cell count and performance.
One study reported a significant reduction in viability of non-encapsulated probiotics at both 37 °C and 4 °C temperatures as compared with encapsulated probiotics; by the fifth week, almost no viable cells remained in the non-encapsulated form. However, this research was conducted to assess viability in orange juice, which is a limitation in extrapolating to supplements such as capsules and powders.
Nevertheless, a look at the store shelves will reveal that most probiotic supplements are stored at room temperature (also referred to as ambient temperature or the temperature prevailing in a working environment.)
Ambient storage of dry powdered probiotics is desirable for manufacturers’ cost reduction and customers’ convenience. The 2019 review titled The Production and Delivery of Probiotics: A Review of a Practical Approach stated, “Currently, probiotics may be incorporated in dietary supplements and other “dry” food matrices which are expected to have up to 24 months of stability at ambient temperature and humidity.”
As detailed in Probiotics Retailer Education White Paper published by the Council for Responsible Nutrition (the leading trade association representing dietary supplement and functional food manufacturers and ingredient suppliers):
“Often, probiotics are manufactured with sufficient overages to ensure claimed quantity at the end of shelf life when stored as directed. However, refrigeration at the retail store should be considered if probiotic products contain highly unstable strains, including most of the Bifidobacterium genus.”
Other researchers suggest refrigeration as an extra safeguard.
“… even in encapsulated form, it should be refrigerated at least after opening the package to maintain the probiotic potency, because the humid conditions of the atmosphere cause metabolic fermentation or degradation. “
The International Probiotics Association and the Council for Responsible Nutrition have developed scientifically-based voluntary guidelines that address storage recommendations (together with labeling and stability testing recommendations) for probiotic-containing dietary supplements. These guidelines are intended to facilitate transparency and consistency. Importantly, stability testing should be conducted under the same temperature conditions as the recommended storage conditions on the finished product label.
The following is an excerpt from the publication IPA Best Practices for Probiotics in Dietary Supplements, which is available to download on the IPA website.
“Probiotic organisms are generally sensitive to changes in temperature and humidity. The degree that an individual product is impacted by temperature and humidity is dependent on the probiotic strains in the product, formulation matrix and dosage form, and product packaging. Manufacturers should provide storage and handling instructions to customers, taking into account individual formulations and packaging. Instructions should be based upon data and experience with each product and should take into account all of the environments in which the product will be reasonably expected to be held throughout its lifecycle (e.g., warehouse, shipping, retail and consumer shelves).”
The probiotic industry may consider storage conditions from the International Conference on Harmonisation (ICH) Harmonised Tripartite Guideline for Stability Testing of New Drug Substances and Products Q1A(R)27 or the United States Pharmacopoeia (USP) General Chapter Packaging and Storage Requirements.
For example, the USP published the revised 2017 (659) Packaging and Storage Requirements for dietary supplements as well as pharmaceuticals and others. Consumers may also use this information as a guideline for at-home storage of probiotic supplements.
- Refrigerator: A cold place in which the temperature is controlled between 2° and 8° (36° and 46° F).
- Cold: Any temperature not exceeding 8° (46° F).
- Cool: Any temperature between 8° and 15° (46° and 59° F).
- Room temperature (also referred to as ambient temperature): The temperature prevailing in a working environment.
- Controlled room temperature: The temperature maintained thermostatically that encompasses the usual and customary working environment of 20°–25° (68°–77° F).
- Warm: Any temperature between 30° and 40° (86° and 104° F).
- Excessive heat: Any temperature above 40° (104° F).
- Dry place: A place that does not exceed 40% average relative humidity at 20° (68° F) or the equivalent water vapor pressure at other temperatures.
New technologies and painstaking care in production, transport and storage deliver most probiotic supplements at ambient temperature. Check the label for storage instructions for the specific probiotics that meet your intended clinical need. Not all labels will have that information though.
But if you have a little extra room in your refrigerator? Go ahead and store them there. It won’t hurt and it may keep more of those beneficial microbes alive.
Cabello-Olmo, Miriam et al. “Influence of Storage Temperature and Packaging on Bacteria and Yeast Viability in a Plant-Based Fermented Food.” Foods (Basel, Switzerland) vol. 9,3 302. 7 Mar. 2020, doi:10.3390/foods9030302
Fenster, Kurt et al. “The Production and Delivery of Probiotics: A Review of a Practical Approach.” Microorganisms vol. 7,3 83. 17 Mar. 2019, doi:10.3390/microorganisms7030083
Hossain, M.S., Al-Bari, M.A.A., Mahmud, Z.H. et al. Antibiotic resistant microencapsulated probiotics synergistically preserved orange juice. BMC Nutr 2, 59 (2016). https://doi.org/10.1186/s40795-016-0098-y
Piqué, Núria et al. “Health Benefits of Heat-Killed (Tyndallized) Probiotics: An Overview.” International journal of molecular sciences vol. 20,10 2534. 23 May. 2019, doi:10.3390/ijms20102534
Yoha, KS et al. “Targeted Delivery of Probiotics: Perspectives on Research and Commercialization.” Probiotics and antimicrobial proteins, 1–34. 27 Apr. 2021, doi:10.1007/s12602-021-09791-7