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We’ve been making potent, multi-strain probiotics for over twenty years, and our products are available in over 40 countries. VSL#3® is the #1 gastroenterologist-recommended multi-strain probiotics brand, and we are proud to introduce a new member of our family, VSL4 Gut.

Learn more about what makes our products special.

The Importance of Potency

Colony-forming units, or CFU, are a unit of measurement used to determine the number of bacterial cells in probiotics. Adequate CFU counts are essential for probiotics to work.

VSL#3® offers some of the highest-potency options available, ranging from 112.5 billion to 900 billion CFU per serving. 

VSL4 Gut is also potent, with 30 billion CFU per capsule.

In addition, while some probiotic brands quote their potency based on the bacteria present at the date of manufacture, we guarantee the labeled CFU count of our products at expiration if stored under recommended conditions. This means you get more of what you pay for.

1

The Importance of Strain Diversity

Research suggests that biodiversity in the gut microbiota can symbiotically promote overall gut health and make the microbiota more capable and resilient, which, as mentioned above, can support multiple health systems.

2

VSL#3® contains eight complementary strains from three different genera. It has been shown to manage microbial imbalances associated with certain digestive conditions. 

3

VSL4 Gut contains a new shelf-stable formulation called OttaBac, which is composed of the same eight strains found in VSL#3® but in a different ratio.

The Importance of CFU Survival

For probiotics to be effective they need to reach the intestines in sufficient quantities. Once there, they can adhere to the intestinal walls to colonize and interact effectively with your microbiota. This interaction allows them to compete with bad bacteria for adhesion sites and nutrients, produce antimicrobial substances, and modulate the immune system by enhancing gut barrier function and reducing inflammation.

VSL#3® is optimized to reach the intestinal tract in two unique ways:

  1. We use a “cold chain” supply chain, which is a temperature-controlled supply chain comprising refrigerated production, storage, and distribution facilities. We then ship VSL#3® to you in thermally lined, refrigerated shipping boxes. These measures ensure that our bacteria arrive alive and ready to colonize your gut. 
  2. VSL#3® is formulated to survive the harsh conditions of the gastrointestinal (GI) tract. In fact, it has been shown to have a 99% survivability rate after 120 minutes in a model of synthetic stomach acid - significantly higher than many of the other products tested1.

The Importance of Research

Research helps identify and verify the specific health benefits associated with different probiotic strains and formulations, to help ensure that consumers receive products that are both safe and effective. 

We are committed to helping the scientific and medical communities better understand the effects of probiotics on the microbiota and overall health. VSL#3® has been the subject of more than 40 scientific publications in the last five years alone. Researchers turn to VSL#3® because of its potency, eight-strain diversity, refrigerated bacteria, and overall quality. 

VSL® Probiotics vs The Other Guys

Probiotic Medical Food Brands

VSL#3®**

Visbiome®**

CFU per Serving (billions)

112.5-900 

112.5-900 

# of Strains

8

8

Refrigerated

yes

yes

Medical Food

yes

yes

Dairy Free

yes

no

The #1 gastroenterologist-recommended multi-strain probiotics brand

yes

no

**VSL#3® is a registered trademark of VSL Pharmaceuticals, Inc.; Visbiome® is a registered trademark of ExeGi Pharma, LLC

Probiotic Supplement Brands

VSL4 Gut Capsules***

Align® Probiotic 24/7 Digestive Support Capsules***

Culturelle® Digestive Daily Probiotic Capsules***

CFU per Serving (billions)

30

1

10

# of Strains

8

1

1

Refrigerated

no

no

no

Medical Food

no

no

no

Dairy Free

yes

no

yes

***VSL4 is a pending trademark of Actial Farmaceutica S.r.l.; Align® is a registered trademark of The Procter and Gamble Company; Culturelle® is a registered trademark of DSM IP ASSETS B.V.