Probiotics: Defining Quality

Discoveries about how the gut microbiota affects human physiology are multiplying at an astounding rate, reshaping much of what we know about health and disease.

Thousands of probiotic supplement brands are now available on the market as millions of people now regularly consume these supplements. However, that does not mean that all probiotics are equal when it comes to quality!

So how do you choose a good quality probiotic supplement?


Probiotics are not one-size-fits-all remedies, and certain probiotic strains are much more effective for certain medical conditions and symptoms than others. Look for supplements with specific strains based on your needs.

Among the known probiotic bacteria, species of lactic acid bacteria (LAB) (Lactococcus, Lactobacillus, Streptococcus, and Enterococcus) and Bifidobacterium have a long history of safe use, possess the ability to withstand digestion and the gut’s high acidity, and have been consistently shown to exert the biological functions.


Vitamins and other supplements typically indicate dosages in terms of weight or volume. For probiotics, weight and volume mean little. What’s important is the number of living microorganisms that survive and replicate after being consumed – and the standard indicator for that is the quantity of colony-forming units (CFUs) per dose. In short, CFUs estimate the expected number of viable organisms a probiotic capsule will deliver to the intestines.

For common commercially available probiotics, label claims run somewhere between 1 billion to 10 billion CFUs per day.
The product quality matters. It’s important to look for probiotics that contain at least 106 (1 million) CFUs per gram, as research suggests that this is the minimum amount needed to exert positive effects in the body.


Because probiotics are quite vulnerable to factors like temperature change and storage time, many may no longer be viable by the time the product is purchased. We therefore recommend that you choose products that include CFUs at the end of a product’s shelf life, which indicates that a product contains a therapeutic number of CFUs after the product is purchased.

Some probiotics also require refrigeration. Check the product label for proper storage instructions. In general, probiotics are sensitive to heat. Thus, if they don’t require refrigeration, you’ll want to store them in a cool, dry area.