What is CFU in Probiotics?

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what is cfu in probitoics?

Scientific Definition

Colony-forming unit (CFU) is the minimum number of separable cells on the surface of or in a semi-solid agar medium which gives rise to a visible colony of progeny on the order of tens of millions. CFUs may consist of pairs, chains, and clusters as well as single cells and are often expressed as colony-forming units per milliliter (CFU/ml).  (CDC)

Don’t worry! Let me simplify.

Viable cell count

CFU stands for “colony-forming unit,” a measurement unit used to quantify the number of viable cells (live and active bacteria or yeast) present in a probiotic supplement or food.

The number of functioning microorganisms

In other words, CFUs indicate the number of microorganisms in a product that is capable of forming colonies, which is an important factor in determining the potency and effectiveness of a probiotic supplement.

The CFU figures per serving that you used to have found on the labels of your probiotic supplement means the number of live microorganisms that you can expect to find in that serving. The recommended dosage of CFUs varies depending on the specific strain of probiotics, the intended use, and the individual’s needs.

Why does CFU count matter in Probiotic supplements?

what does cfu count matter in probiotics supplements?

CFU count is an important consideration when choosing a probiotic supplement because it reflects the number of viable and active microorganisms present in the product. 

The Higher, the better

The higher the CFU count, the greater the number of live microorganisms that are available to potentially colonize the gut and confer health benefits.

Survival of the “fittest”

The effectiveness of a probiotic supplement depends on the ability of the live microorganisms to survive transit through the acidic environment of the stomach and colonize the gut. Therefore, a higher CFU count may increase the chance of some of the microorganisms surviving and colonizing the gut.

Limitation of CFU in probiotic potency

However, it’s noteworthy that a higher CFU count doesn’t always mean a better product. The effectiveness of a probiotic supplement also depends on the following factors.

(a) specific strains of microorganisms included (i.e. some strains may be effective at lower CFU counts, while others may require higher CFU counts to be effective) 

(b) the quality and purity of the ingredients and

(c) the manufacturing process.

So, how to interpret CFUs on Probiotic labels? 

how to interpret cfu on probiotics lables?

Interpreting CFUs when choosing the right probiotic food or supplement can be literally confusing. The following are some tips you may easily apply the next time you are purchasing probiotics. 

  • Look for the total CFU count:   Look for a product that has a CFU count of at least several billion.
  • Check the number of strains: It means the number of different types of organisms contained in the product. Try to look for a product that contains several different strains of microorganisms, as this may increase the likelihood of health benefits.
  • Look for a viable until date: Some probiotic supplements will have a “viable until” or simply “an expiry date” on the label. It is important to make sure the product you choose is viable for maximum effectiveness.
  • Check the specific strains: The specific strains of microorganisms included in a probiotic supplement can impact its effectiveness. Eg. Lactobacillus acidophilus and Lactobacillus rhamnosus are beneficial for Bacterial Vaginosis while Bifidobacterium is useful for the prevention and treatment of Urinary tract infections.
  • Consider your individual needs: The specific CFU count and strains of microorganisms that are effective for one person may not be the same for another. Consider your individual health needs and it is advisable to consult with a healthcare provider before choosing a probiotic supplement.


CFU is one of the most important factors you have to consider when choosing the right probiotic for you. It indicates the potency and efficacy of the probiotic supplement you are likely to consume. Meanwhile, it is not the sole indicator of potency since there are some other factors you have to be aware of as I mentioned above. Hope you can apply this knowledge the next time you buy yogurt at a supermarket or a probiotic supplement at your pharmacy. 

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Dr Tun Min is s GP working in NHS UK and writing articles about supplements and vitamins based on personal clinical experience and clinical research.

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