CFUs vs. Strains: The Ultimate Probiotic Explainer

Image Credit: Hiraman/E+/GettyImages

You've been hearing about probiotics for years now, and may have already added them to your supplement shelf. But do you really know what's going on inside your probiotic bottle? It's official: You're not the only one a bit confused on this subject.

Potency guarantee, clinically studied strains, and CFUs are all important factors that go into choosing the right probiotic for your body. So, if you don't know what these terms mean, how are you supposed to reap all the gut-friendly benefits?

To help figure this out, we tapped Zac Lewis, PhD from Renew Life, to get down and dirty in all things probiotics.

Image Credit: triloks/iStock/GettyImages

1. What is a CFU and what does it do?

CFU means colony forming unit, and is used interchangeably with the phrases "live cultures" and "culture count." Translation: This refers to the "good bacteria" probiotics are famous for.

Put more technically: "It refers to the method we use to measure live microbes by spreading the contents of the capsule onto a petri dish, culturing the microbes, and counting the number of dots (colonies) that appear," says Dr. Lewis.

In order for your probiotic to put in the work—and for you to receive all the gut-happy positives—Dr. Lewis says it should have the amount of live microbes required to back up the benefits listed on the bottle, all the way to the end of its shelf life.

Renew Life probiotics deliver powerful formulas with strains guaranteed to live through the end of your supply's shelf life, so that every bottle (like Ultimate Flora, with 30 billion live cultures) does just the trick—and maybe even a little more.

2. What are strains and why are they important in probiotics?

Strains are the unique classifications of microorganisms, and different strains come with different attributes and qualities. To simplify things a bit, Dr. Lewis uses pets as an analogy for understanding the various levels of strains (because pet references make everything better).

"Most probiotic strains fall into two big groups (genera); the bifidobacteria and the lactobacilli. Think about that being like the differences between cats and dogs," he says. "Sure, they share some things in common like being furry and having four legs, but there are also lots of differences."

Next, there's the species level, such as Bifidobacterium breve. Dr. Lewis likens to the difference between wolves and dogs: "More related than cats and dogs, but still having lots of differences."

And finally, there's the strain level—the most specific way to refer to a type of bacteria. "Different strains are like different types of dogs—chihuahuas and St. Bernards," explains Dr. Lewis. "You still want to pick the right strain with the right abilities. German Shepherds make great guard dogs and Dachshunds make great lap dogs, but using them the other way around doesn't make much sense."

In other words, if you're having a specific gut issue like gas or IBS, opt for a strain that targets that specific issue. The more variety of strains you have, the more you'll be covering the full spectrum of gut-health problems, too.

Image Credit: nortonrsx/iStock/GettyImages

3. So what should you look for when choosing a probiotic?

When you hear the word "bacteria," the happiest of thoughts don't immediately jump to mind. But Dr. Lewis wants to change that. "Not all bacteria are bad! You have about 40 trillion bacteria living in and on you right now, and they are important partners in your everyday health," he says.

People also believe that CFUs and strains are the same, or think you only need one or the other, but in reality they serve different purposes and work together, according to Dr. Lewis. Different strains can provide different benefits, and enough CFUs of every strain must be in a product in order for people to experience the full goodness, like Renew Life's high-potency probiotics. Bonus: They come in a variety of customized formulas depending on your needs, stage in life, and more.

"Follow the clinical science!" says Dr. Lewis. Renew Life certainly does, and offers a variety of potent customized formulas depending on your needs, stage in life, and more.

"We're obsessed with using the right strains backed by the right clinical science for the right health needs, ensuring the highest in product quality, and providing effective CFU levels through the end of shelf life," Dr. Lewis notes.

Now when the topic of probiotics makes its regularly scheduled pop-up in your lunch convo, you can confidently know exactly what you're putting in your body—and score all the buzzed-about benefits, too.

Is This an Emergency?

If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911. If you think you may have COVID-19, use the CDC’s Coronavirus Self-Checker before leaving the house.