VSL#3 is a probiotic supplement which is marketed under the category of “medical food”.
It is a high-potency encapsulated probiotic available in both prescription and non-prescription strengths. There are currently four different formulations, each with a different dose of live bacteria.
VSL#3 is specifically designed and intended for the management of ulcerative colitis (occurring with Inflammatory Bowel Disease), ileal pouches, and Irritable Bowel Syndrome.
Some individuals use VSL probiotic capsules in the treatment of Crohn’s Disease, although this is an off-label use.
What is a Medical Food?: Medical foods are those which meet three basic criteria:
- provide a distinctive nutritional need with regards to a disease or condition which is unable to be met with diet alone
- must be taken under the supervision of a doctor
- Is intended for dietary management of a specific condition or disease.



- Supports a healthy immune system & microflora
- Promotes digestion & nutrient absoprtion
- Combats pathogenic bacteria; Improves metabolism
VSL Probiotic Benefits
Related Topics
- What are Probiotics?
- Probiotic Benefits
- Best Probiotic Strains
- Probiotic Side Effects
- Probiotic Supplements
- Probiotic Foods
- Best Probiotic Yogurt
- Probiotics for Children
- Probiotics for Women
- Yeast Infections
- What are Prebotics?
- Lactobacillus Acidophilus
- Lactobacillus Bulgaricus
- Lactobacillus Rhamnosus
- Bifidobacterium Bifidum
- Bifidobacterium Infantis
- Bifidus Regularis
VSL is a unique product because not only has each strain of bacteria contained in it been clinically tested on its own, but research has also been done using the probiotic food with all eight bacteria collectively, as a whole. Medical food falls under different regulatory criteria than other supplements.
A prescription-only strength formula of VSL#3 (VSL#3-DS) is specifically for patients with ulcerative colitis and for ileal-pouch patients. In other words, the prescription strength formula has not been shown to benefit individuals diagnosed with Irritable Bowel Syndrome.
VSL contains high quantities of 8 different strains of lactic acid bacteria specifically chosen because they work synergistically together to create a balance in the gut microflora which is beneficial for their human host.
Mechanisms of Action
VSL acts as a protective barrier along the digestive tract, inhibiting pathogenic bacteria from harming the inner layer of the gut mucosa.
Pathogenic bacteria which are unable to find space to colonize are unable to compete against the incoming cascade of probiotic microorganisms contained in this probiotic capsule.
Additionally, studies suggest that VSL probiotics help the outer layers of the gastrointestinal tract to become less permeable.
It does this by encouraging tightening of the junctions between the cells, thus reducing the likelihood of pathogens leaving the intestinal tract and transmigrating to other locations within the body via the bloodstream.
Finally, the probiotic strains contained in VSL work to impact intestinal mucus production and may have an effect on immune processes. Research is ongoing in this field.
Formulations and Dosage
VSL#3 is available without a prescription, whereas VSL#3-DS requires a prescription from your medical doctor.
Every dose of VSL contains a combination of these 8 probiotic bacteria:
- Bifidobacterium breve
- Bifidobacterium longum
- Bifidobacterium infantis
- Lactobacillus acidophilus
- Lactobacillus plantarum
- Lactobacillus paracasei
- Lactobacillus bulgaricus
- Streptococcus thermophilus
Although there are 4 different formulations of VSL, all of them contain a combination of the same 8 strains of lactic-acid bacteria.
The difference between the formulations lie in the dose contained within them. The different formulations are as follows:
- Packets of powdered probiotic bacteria containing 450 billion live bacteria
- Capsules containing 112.5 billion live bacteria
- Junior packets containing 225 billion live bacteria
- DS – double strength packet sachet containing 900 billion live bacteria (prescription only)
The manufacturer makes these recommendations for medical professionals who are prescribing VSL for their patients:
Adults:
- For IBS, take 2-4 capsules each day, or ½ -1 full packet of powder.
- For Ulcerative Colitis, take 4-8 capsules, or 1-2 packets of powder per day.
- For Pouchitis, take 2-4 packets of powder per day.
- For Active Ulcerative Colitis, take 4-8 packets of powder per day.
Note: For patients with Active Ulcerative Colitis, the dose may need to be high, at least initially. This is specifically what the DS (double-strength) prescription formula is created to address.
Children: Follow the directions of a professional medical provider regarding the correct dose and frequency of this potent probiotic formula. Results are usually experienced within 7-21 days.
Side Effects
Because of the potency of VSL formulas, individuals may initially experience bloating, gas and even some mild abdominal discomfort as both the body and GI tract adjust to the new microflora balance. For most people these side effects are mild and subside with continued use.
Some people may not be able to take VSL because of the potency. If this is the case, there are other quality probiotic formulas which are less potent and may help to prepare the gastrointestinal tract for a higher strength formula like VSL.
VSL may contain small amounts of lactose or skim milk product. Individuals with allergies to lactose should not take VSL products.
Individuals with weakened or compromised immune systems should not take VSL#3 products.
Review
VSL brand probiotic products are high-potency supplements which meet the criteria of Medical Food. The standards are a bit more rigorous for this category of supplement and research has been done to assure VSL products meet these standards.
For individuals with Inflammatory Bowel Disease Ulcerative Colitis, and for ileal-pouch patients, VSL probiotic is a good choice and may even be covered by some insurance carriers.
Other probiotic supplements may be a better choice with individuals who do not have prescriptions from their doctors.
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Article last updated on: April 29th, 2018 by Nootriment
4 Comments
I have taken Flagyl very regular for recurring pouchitus. It caused lips. Gums.tounge and into throat to hurt and swell with white patches. Can only drink cold liquid without crying. Hope this helps my mouth and j pouchitus too
Question Are there “prebiotic” in VSL? I heard that if you are taking “prebiotic” with probiotics you are wasting your money, is that true???
I am just taking this vsl#3cap. Hope it will better
Thanks for letting us know! It would be great if you could leave a review of the product when you have a chance.