VSL#3(VSL3): Mega-Probiotic for IBS, UC, and Pouchitis

VSL#3 (AKA "VSL3") is a high-potency probiotic medical food intended for the dietary management of ulcerative colitis (UC), IBS (irritable bowel syndrome) or an ileal pouch.  Its trademark description is “The Living Shield”, which I think is very fitting for what probiotics do.

One thing to note, however, is that this is NOT the same VSL#3 that was used in studies prior to 2016. You will find out the significance of that in a moment. It is produced by Alfasigma.

What Kind of Supplement is VSL3?

VSL#3 is a medical food, which means, according to the US FDA:

  • It is a specially formulated and processed product (as opposed to a naturally occurring foodstuff used in its natural state) for the partial or exclusive feeding of a patient by means of oral intake or enteral feeding by tube, meaning a tube or catheter that delivers nutrients beyond the oral cavity directly into the stomach or small intestine;2
  • It is intended for the dietary management of a patient who, because of therapeutic or chronic medical needs, has limited or impaired capacity to ingest, digest, absorb, or metabolize ordinary foodstuffs or certain nutrients, or who has other special medically determined nutrient requirements, the dietary management of which cannot be achieved by the modification of the normal diet alone;
  • It provides nutritional support specifically modified for the management of the unique nutrient needs that result from the specific disease or condition, as determined by medical evaluation;
  • It is intended to be used under medical supervision; and
  • It is intended only for a patient receiving active and ongoing medical supervision wherein the patient requires medical care on a recurring basis for, among other things, instructions on the use of the medical food.

Medical foods are NOT drugs and therefore do not have to go through the FDA drug-approval process.

What Probiotics are in VSL#3?

VSL3 is composed of 8 strains of lactic acid bacteria. (Note that the strain names are not on the VSL3 website, but were published in some of the studies referenced below):

  1. S. thermophilus  BT01
  2. B. breve BB02
  3. B. longum BL03 (recently reclassified as B. lactis)
  4. B. infantis BI04 (recently reclassified as B. lactis)
  5. L. acidophilus BA05
  6. L. plantarum BP06
  7. L. paracasei BP07
  8. L. delbrueckii sub.bulgaricus BD08 (recently reclassified as L. helveticus)

What Products Contain VSL#3?

At the time of this writing, VSL3 is available in 3 different products: Please always check ingredients prior to consumption!

  1. Capsules containing 112.5 billion CFU per capsule, hydroxylpropylmethylcellulose, cornstarch, magnesium stearate, silicon dioxide, stearic acid, microcrystalline cellulose.
  2. Unflavored packets containing 450 billion CFU per packet, cornstarch, silicon dioxide.DS (double strength) sachets containing maltose, 900 billion CFU per sachet, cornstarch, silicon dioxide.
  3. The DS formula is available only with a prescription.
    The powder should be mixed with only cool foods (applesauce, yogurt, cold soup, etc.) or cool non-carbonated liquids. The capsules may be opened and the contents mixed with cool foods or cool non-carbonated liquids. 

How Much is Recommended?

At the time of this writing, the product website for healthcare professionals recommends:

Please note that consumers are supposed to be working with a physician for treatment with these conditions. Follow your doctor’s recommendations as to usage.

When Can You Expect Results?

According to the website, “Adjustment of the intestinal flora can take a few days or weeks; it may take up to 1 month for the colonization of the gut to become optimally stable.”

What Does the Research Show?

To my knowledge, there are limited studies with this product as of December, 2019. As noted on the Visbiome page, scientific studies performed prior to 2016 should be credited to Visbiome and NOT to VSL3, not only because of the ratios of the different probiotic organisms, but also because of the different culturing conditions. Additionally, studies performed in 2017 may or may not have been performed with this Alfasigma product. You can read more about the lawsuit involving Visbiome and VSL#3 on the Visbiome page.

Here are some studies I found:

A research summary  published in March of 2019 with VSL#3 (Alfasigma) in IBD patients investigated the presence of fecal high mobility group box 1 (HMGB1) index, an important proinflammatory mediator involved in IBD development. A mouse colitis study and in vitro study were also performed comparing #3 to a Bifidobacterium longum strain. Results showed that HMGB1 were high in both active IBD and colitis mice. After treatments with the 2 investigated probiotics there were reduced serum and fecal HMGB1 levels as well as increased expression of zonula occludins-1, occludin, and claudin-1 in colon tissues of mice. In vitro, HMGB1 reduced transepithelial electrical resistance, zonula occludins-1 protein expression, and increased paracellular permeability of FITC-dextran, showing that it plays a role in IBD. Probiotic treatments had the opposite effects.

A small, pilot crossover study published June, 2019, in which the authors declared no conflict of interest, compared this probiotic and Visbiome. Results showed that feces from 10 healthy donors obtained prior to probiotic intake and feces collected after supplementation with VSL3 did not affect Candida albicans growth. On the contrary, a 3log10 inhibition of Candida growth was observed with Visbiome intake (as the European version, Vivomixx).

An in vitro wound-healing study from 2017 to test the ability of probiotics to protect gastrointestinal mucosal surfaces was undertaken with this product and Visbiome. The results showed that Visbiome did not affect monolayer morphology (cell structure) and cell density (favorable results), but VSL#3 “caused clear morphological cell damage and strongly reduced cellularity" (unfavorable results). Visbiome was declared to have protective effects, including reactive-oxygen species protection, whereas the other product did not.

A 2017 study in mice with induced colitis showed that VSL#3 and (what now is) Visbiome purchased in the UK had different effects. Visbiome, but not VSL#3, attenuated “clinical” scores of colitis.

Another study was published in 2017. In a small cohort of patients receiving combined antiretroviral therapy for HIV-1, what is now known as Visbiome was used, and then in vitro studies were performed to compare Visbiome (the previous US-made VSL#3) to VSL#3 (Alfasigma). The ultimate conclusion was, “Our data, in conjunction with previously published findings, confirm that the new Italian-made formulation of VSL#3® is different from the previous US-made VSL#3 and therefore its efficacy and safety in HIV-infected subjects is still unproven.”

PROS of VSL#3, In My Opinion

  • Multiple species, as research shows it takes a village of probiotic organisms to be healthy
  • Live freeze-dried lactic acid bacteria
  • Super-high potency
  • If stored under refrigeration (36-46°F or 2-8°C), VSL#3 products are guaranteed through the "Best if used by" date, not the manufactured date.
  • Can be stored at room temperature (77 degrees F) for up to 2 weeks without a significant effect on potency
  • May be frozen, but not thawed and refrozen
  • Vegetarian capsule
  • All formulations are free from wheat, gluten (other cereals), soy, milk including lactose, crustacean shellfish, eggs, peanuts, nuts, fish, celery, mustard, sesame seeds, sulfur dioxide and sulfites (>10 mg/kg), lupin, mollusks (Read ingredients!)
  • Kosher and Halal certified
  • Non-GMO cornstarch in the unflavored powder, and nothing else is GMO in any of their products

CONS of VSL#3, In My Opinion

  • Expensive (but some insurances may cover it)
  • No published clinical trials with this formulation to date (Dec 2019)
  • Daily consumption of high levels of VSL3 is needed to maintain adequate and balanced bacterial colonization. You can't take it sporadically. (But then again, daily consumption of probiotics is a good idea in most cases anyway.)
  • Definitely requires refrigeration long term. VSL3 can be stored at room temperature (77°F) for up to 2 weesk without having a major effect on potency, but after that or if exposed to high temperatures, the number of beneficial bacteria can become significantly reduced.
  • Like any probiotic, this one can cause bloating and gas when it is first being used until the body and flora adapt to the changes. Because all the forms of the product are so highly potent, it may be best to use partial dosages when starting them. You might have to weather some discomfort until your intestines get used to the new environment.

Where to Buy VSL#3?

Your local pharmacy may carry the non-prescription products. At this time the product is not found at Amazon.com or other distributors I work with.

Obviously, the prescription "DS" product is only available with a prescription from your doctor.


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