Probiotics are live microorganisms, including certain bacteria or yeasts, that provide a health benefit when taken in adequate amounts. A supplement’s formula and packaging are intended to help those microorganisms remain viable, or alive, during storage.
The number of live microorganisms can decline over time. Heat, moisture, oxygen, and storage conditions can affect how well a product holds up, so the date on the package matters alongside the storage instructions.
In a study of 33 expired probiotic products, researchers found live microorganisms in some products after their expiration dates. Most tested products, however, had counts well below the amounts recommended by their manufacturers for use.
The products in that study varied in age, packaging, and storage conditions. Its results don’t tell you how many live cultures remain in your bottle, or establish a safe period for using any probiotic after its date.
Key Takeaway: Expiration isn’t an instant switch from live to inactive. It’s a point after which you shouldn’t count on the product to retain its labeled potency.
What Do CFUs Mean?
A label may list a serving’s colony-forming units, or CFUs. This is a measure used to estimate the number of viable microorganisms in the product.
A CFU count is useful when it’s considered with the specific strains and the date through which the count applies. A higher number alone doesn’t tell you that one probiotic is better for your particular goal.
If a label gives a count only at the time of manufacture, that number doesn’t tell you how many live cultures will remain later. Look for clear information about the amount expected through the product’s expiration date when stored as directed.
Is a Best-By Date Different From an Expiration Date?
You may see “best by,” “use by,” or “expiration” on a probiotic package. A best-by date generally speaks to product quality, while an expiration or use-by date tells you when the product is intended to be used.
The wording doesn’t let you calculate how many live cultures remain afterward. For any of these dates, following the label and replacing a product that has passed its date is a reasonable way to avoid relying on uncertain potency.