As you browse for probiotic supplements, have you ever wondered what probiotics actually are? Probiotics are live microorganisms living in our bodies and are often known as “friendly” or “good” bacteria. These bacteria actually help the digestive system and body in a number of ways!

When studying a probiotic supplement label, you’ve probably noticed some letters on the Supplement Facts Panel (SFP) next to the probiotic strand name — CFU or AFU.

If you’ve been wondering what these measurements mean, or which to choose, we’re here to help!

Colony Forming Units vs. Active Fluorescent Units

CFUs (Colony Forming Units) and AFUs (Active Fluorescent Units) are ways to measure probiotics. Just like you may see grams (g), milligrams (mg) or micrograms (mcg) on an SFP next to a nutrient, you’ll instead see CFU or AFU next to probiotic strain(s).

• CFUs are the traditional way to measure probiotics. This number reflects how many probiotic cells might be alive and able to grow when tested in a lab. However, this method can’t tell if those cells are truly alive or active when you actually take them.

• AFUs are a newer, more advanced method. They use precise technology to count only the live and active probiotic cells, the ones that are ready to support your gut, immune system, and overall health.

  
  

Think of it this way:

• CFUs = Estimated potential

• AFUs = Real-time, active results

Choosing a product measured in AFUs gives you more confidence in what you’re taking. You’re not just hoping it works, you know it’s working.

The “Seeds vs. Sprouts” Analogy

An easy way to understand the key differences between these units is to liken them to seeds versus sprouts.

When it comes to probiotics, CFUs (Colony Forming Units) are like counting how many seeds you plant in a garden. CFUs tell you how many probiotic cells might be alive and capable of growing when you take them, but not all seeds grow into healthy plants.

That’s where AFUs (Active Fluorescent Units) come in. AFUs are like counting the sprouted plants that are already growing: they measure how many live, active probiotics are truly ready to work in your gut right now.

Why does this matter?

AFUs give a clearer, more accurate picture of what’s inside your supplement and how much of it your body can actually use.

So, while CFUs tell you what could happen, AFUs tell you what is happening.

What’s better: CFUs or AFUs?

Let’s break it down a bit more in plain terms:

• CFUs have been used for a long time to measure probiotics. They tell you how many probiotic cells might be alive when the product was made. But CFUs don’t always reflect how many of those cells survive storage, shipping, or even digestion. It’s more of a best guess.

• AFUs, on the other hand, are typically a smarter and more accurate measurement. They count only the probiotic cells that are alive, active, and ready to do their job in your body right now.

This means with AFUs, you get a more trustworthy, real-world number.  

MaryRuth’s Probiotics With Guaranteed AFUs

And with our two refrigerated probiotics, the Women's Wellness Probiotic Capsules and Cognition & Digestion Probiotic Capsules both contain guaranteed AFU and CFU in every serving.  

The Women's Wellness Probiotic Capsules contain a blend of 8 robust probiotic strains with 90 billion CFU & AFU guaranteed per serving. This helps you maintain balance where it matters most: your gut and vaginal microbiomes. This blend also supports a healthy gut microbiome and digestive function, key to everyday wellness and comfort.

The Cognition & Digestion Probiotic Capsules have 64 billion CFU & AFU guaranteed per serving with a proprietary blend of 29 unique strains to maintain a healthy gut microbiome while also supporting cognition. Just one capsule supports regular bowel movements during times of stress, at which the frequency might increase!

If you want a supplement that gives you real, active support for your digestion, energy, and immunity, you’ll want to choose a product measured in AFUs.

Ultimately, it’s up to you to decide what is best for your needs, and we hope that this has helped!