As more is known about the relationship between gut health, the immune system, and overall wellness, probiotic supplements are projected to become an $85 billion industry by 2027. With this popularity has come heightened consumer scrutiny: in order to be effective, these “friendly” bacteria must be kept alive, and not all brands deliver.
Probiotic efficacy is a numbers game. Depending on the bacterial strain, encapsulation method, and the physiology of the end user, only a certain percentage of live, colony-forming units (CFUs) will survive the acidic environment of the stomach to reach the lower digestive tract. When more CFUs are alive at the time the product is ingested, more are likely to make it beyond the stomach.
High CFU counts are a primary selling point for probiotic supplements, but when CFUs present during manufacturing don’t survive the product’s shelf life, label claims issues emerge. Because myriad factors can impact CFU survival, including environmental conditions, packaging, and formulation, the only way to verify viable counts and set scientifically valid expiration dates is through consistent stability testing.
How Third-Party Labs Quantify CFUs
A “viable count” of CFUs indicates the number of microorganisms in a sample that can grow and reproduce in a laboratory.
This is accomplished by incubating a diluted sample and using the resulting microbial count to calculate the number of living colonies in a full dose of the product. For complex probiotic blends, laboratories may test individual microbial strains by incubating samples under specific conditions to get separate counts for each.
Results are easily influenced by temperature, oxygen levels, and incubation time, so validated stability testing methods are imperative for consistent, accurate CFU counts.
What Influences Probiotic Stability?
Probiotic microorganisms are sensitive to environmental conditions, and like all living things, their viability naturally decreases over time. To prolong their useful shelf life and set accurate product expiration dates, it’s important to identify and account for the factors that affect stability.
Heat
Temperature has a significant impact on probiotic survival. Heat speeds up cellular activity and increases stress, causing viable organisms to die faster. Likewise, moisture and humidity can prematurely activate bacteria that have been rendered intentionally dormant, so colonies complete their life cycle before they are ingested.
Oxygen
Oxygen exposure can also affect certain probiotic strains, particularly those that thrive in low-oxygen environments. If packaging and oxygen barrier materials don’t adequately protect these sensitive organisms, many CFUs may be dead on arrival.
Product Format
Formulation choices are another factor in probiotic stability. Enteric capsules, powders, and functional food matrices offer different levels of protection for different microorganisms, both on retail shelves and inside the body. The correct choice of excipients, carriers, and protective coatings can improve microbial survival during storage.
Packaging + Distribution Conditions
Containers with strong moisture and oxygen barriers, along with desiccants, can keep conditions more stable throughout the product’s shelf life. On the other hand, probiotics that aren’t shipped and stored in climate-controlled environments may lose potency before their printed expiration date.
Setting Defensible Expiration Dates Using CFU Data
For probiotics, accurate expiration dates should reflect how long viable counts will remain above the label claim. In other words, the declared number of CFUs should be present for the product’s entire shelf life.
Stability testing validates expiration dates by storing samples under the conditions recommended by the manufacturer and testing them repeatedly over an extended period. This data determines how long microbial counts remain stable, and at what point they begin to decline.
Because real-time studies can take months or years to complete, accelerated stability studies can help manufacturers identify shelf life issues in the early stages of product development.
Accelerated studies simulate the full product lifecycle in a compressed period of time by exposing samples to oxygen, heat, and humidity. The results allow manufacturers to estimate long-range stability and make any necessary improvements to formulas, packaging, or initial CFU counts.
Common Causes of Label-Claims Issues for Probiotics
When probiotics fail to meet their labeled CFU claims, the discrepancy is commonly due to one of these factors:
- Insufficient data. If the stability study used to determine the expiration date doesn’t accurately address real long-term conditions, manufacturers may underestimate how quickly viable counts decline.
- Variability in manufacturing. Inconsistent blending, uneven distribution of probiotic ingredients, or inaccurate dosing during encapsulation can create disparities between batches.
- Storage and distribution. Unexpected exposure to heat and moisture during shipping or storage can reduce CFUs before the product ever reaches consumers.
- Inconsistent methods. Third-party testing laboratories must have validated, consistent processes in order to produce reliable data. Variations in incubation conditions or enumeration methods can affect final counts, so always choose an ISO-accredited facility.
Avoiding Viable Count Discrepancies
Consistent quality control at all stages of production helps keep microbial counts stable. This includes:
- Monitoring the temperature and humidity during manufacturing.
- Verifying consistency between batches.
- Controlling the storage environment.
- Independently verifying CFU counts.
Combined with good manufacturing practices, third-party product testing is the most effective defense against label-claims issues.
Whether you need to intercept potential viability challenges during product development or provide continuous verification for an existing product, stability studies help identify and correct potential label claims discrepancies before they become complex, costly problems.
Protect Potency from Production to Expiration
Probiotics are living microorganisms, and the efficacy of supplement products depends on their long-term survival. Keep CFU counts accurate from start to finish, and ensure that expiration dates are rooted in data.
Inaccurate label claims risk complaints from the FDA, consumer dissatisfaction, and eroded brand trust. Back up meticulous manufacturing practices and quality products with thorough laboratory testing, and let consumers know you deliver on the benefits they value most.
