Colony Forming Units (CFUs): What Are They & How Much is Too Much?

We interviewed Heather Ott, MS, RD about CFUs to support you in learning about probiotic supplements. Heather is a Registered Dietitian Nutritionist (RDN) and Uqora’s Senior Health and Science Educator. She earned a B.S. in Nutritional Sciences from UC Berkeley and a M.S. in Nutritional Sciences from San Diego State University.

Here’s everything you need to know about Colony Forming Units (CFUs).

What is a Colony Forming Unit (CFU)?

A colony-forming unit, or CFU for short, is a unit of measurement used to estimate the number of viable bacteria or fungi in a sample. It measures how many bacteria or fungi are present and capable of dividing and forming colonies. 

You’ve probably landed here because you’re looking for information on CFUs in probiotics, but this is actually a unit of measurement for bacteria in other places too. It is also used when measuring bacteria in urine when you have a urine culture done.

How are CFUs calculated in probiotics?

CFUs indicate the number of viable cells. You often see the amount of CFUs written as “1 x 109” which is 1 billion, or “1 x 1010” which is 10 billion. Most probiotics have been tested at levels between 1-10 billion, but you could even see products that have up to 50 billion CFUs.

How many CFUs are typical for a probiotic?

Probiotic supplements typically contain 1-10 billion CFUs per dose, but probiotics could contain up to 50 billion CFUs per dose. 

It’s important to note that just because a probiotic product has a higher CFU count, doesn’t necessarily mean that it works better than ones with a lower CFU count. It’s always best to do thorough research on which products you choose, so you’re on the right track to find what works best for you!

What makes a quality probiotic?

I’ve seen questions about what makes a quality probiotic – is it the number of CFUs? Or is it the type of bacteria in the probiotic? It’s both! When choosing a probiotic it’s important to take into account both the CFU count and the strain of bacteria. 

First off, you want to make sure that the probiotic supplement you are taking provides the benefits you are seeking. Different strains have been studied in multiple settings like GI issues while others have been studied for vaginal health. So, you need to pick a probiotic based on the health benefits you are looking for. You wouldn’t put on a wool coat in the middle of summer to try to cool down, just like you shouldn’t pick a probiotic that helps with respiratory health if you are trying to target your gut health! It’s also important to consider a blend versus a single strain alone. 

The next part is the CFU count. More is not necessarily better but if a product has clinical studies, the dose needs to match what was used in the clinical studies. The best approach here is to choose the dose that has been tested in a clinical setting and shown to provide positive outcomes. 

Lastly, it’s important to keep in mind storage. Some probiotics may need to be refrigerated, while others may be shelf-stable. 

Conclusion

We’re so glad Heather was able to help you research everything you need to know about CFUs! Ultimately, when it comes to choosing a new supplement, we always recommend doing your research and picking the option that works best for your lifestyle and routine.