The De Simone Formulation in Ireland: Definition, Timeline, and How to Verify Product Identity.
Reference page (Ireland). For public education. Not medical advice.
The De Simone Formulation (DSF) is an 8-strain probiotic mixture developed by Professor Claudio De Simone. Until 2016, this formulation was sold under the brand name VSL#3. After 2016, products sold as VSL#3 no longer contained the De Simone Formulation [1]. Most pre-2016 clinical studies referring to VSL#3 relate to the De Simone Formulation.
DSF is a specific high-potency probiotic formulation developed by Professor Claudio De Simone. Until 2016, DSF was sold under the VSL#3 brand name, and much of the pre-2016 clinical literature that mentions “VSL#3” relates to that original formulation. After 2016, the product sold as VSL#3 no longer contained DSF [1]. ECCO has also stated that VSL#3 references in its 2017 guidelines exclusively endorse DSF supported by scientific evidence, because post-2016 VSL#3 does not contain DSF [1]. In Ireland, the practical question is usually identity: does a product match the original 8-strain composition used in the historic evidence base? This page provides an identity-first reference: the 8-strain list, a timeline, and an Ireland-focused verification section.
1) What is the De Simone Formulation?
The De Simone Formulation (DSF) is a proprietary probiotic formulation and manufacturing approach developed by Professor Claudio De Simone. In published literature and clinical discussions, DSF is described as a multi-strain, high-potency probiotic mixture that was sold as VSL#3 prior to 2016.
The 8-strain composition (species list)
The list below reflects the commonly cited 8-species composition used in published reviews of the historical VSL#3 formulation. Naming and taxonomy can differ across sources and over time; this is a reference list for identification and comparison.
| Genus | Species | Commonly cited as part of DSF / historic VSL#3 mix |
|---|---|---|
| Lactobacillus | Lactobacillus acidophilus | Yes |
| Lactobacillus | Lactobacillus plantarum | Yes |
| Lactobacillus | Lactobacillus casei | Yes |
| Lactobacillus | Lactobacillus delbrueckii subsp. bulgaricus | Yes |
| Bifidobacterium | Bifidobacterium breve | Yes |
| Bifidobacterium | Bifidobacterium longum | Yes |
| Bifidobacterium | Bifidobacterium infantis | Yes |
| Streptococcus | Streptococcus thermophilus | Yes |
In summary, the De Simone Formulation consists of eight bacterial species across the Lactobacillus, Bifidobacterium, and Streptococcus genera. This 8-strain composition is the identity anchor used in pre-2016 VSL#3 clinical literature.
CFU refers to “colony forming units”, a label measure used to describe live microorganisms in a product at a given point in time. CFU numbers alone do not guarantee outcomes; strain identity and evidence alignment matter.
2) The 2016 split (high-level timeline)
In the public record, 2016 marks a key dividing line: DSF was sold as VSL#3, and after 2016 the product sold under the VSL#3 name no longer contained DSF [1]. This distinction matters because many older clinical studies and guideline references relate to DSF rather than later formulations sold under the VSL#3 brand.
| Period | Event (summary) | Practical impact on clinical references |
|---|---|---|
| Until 2016 | DSF sold as VSL#3 | Older studies and guideline references to “VSL#3” often refer to DSF. |
| After 2016 | VSL#3 product no longer contains DSF (per ECCO statement) | Clinicians and patients need to distinguish “brand name” from “formulation used in evidence.” |
| 2021–2022 | US appellate litigation continues around DSF-related advertising and continuity claims | Reinforces that continuity claims between pre-2016 and post-2016 products are contested and should be checked against primary sources. |
Primary sources are listed in section 9.
3) Medical society clarification (ECCO)
ECCO (European Crohn’s and Colitis Organisation) published an official statement clarifying that: until 2016, DSF was sold as VSL#3, and after 2016 the VSL#3 product no longer contains DSF [1]. ECCO also states that VSL#3 references in its 2017 guidelines exclusively endorse DSF supported by scientific evidence, because post-2016 VSL#3 does not contain DSF [1].
Why this matters in Ireland: if you are reading a pre-2016 paper or a secondary summary that uses the name “VSL#3”, you need to confirm whether the product discussed is DSF or a later formulation sold under the same brand name.
4) Where “high strength probiotics” fits (Irish search intent)
In Irish consumer searches, “high strength probiotics” usually means a product marketed as high-potency, often using a CFU number as shorthand. There is no single universal definition of “high strength” across products, and CFU is only one variable.
In Ireland, probiotic products are typically sold as food supplements. Health claims are restricted, and consumers should treat broad marketing claims with caution. For general supplement safety advice, the HSE advises discussing supplements with a GP or healthcare professional where appropriate [8].
Neutral selection checklist (identity-first)
- Strain identity: Which strains are included, and do they match strains used in published human studies relevant to your use case?
- Dose used in evidence: Do published studies for a similar context use comparable dosing and duration?
- Label clarity: Is CFU stated, and are storage instructions clear?
- Safety context: People under medical supervision or who are immunocompromised should seek clinical advice before using live microorganism products.
- Claims discipline: Prefer specific, sourced statements. Treat broad “supports” style claims with caution.
The Food Safety Authority of Ireland (FSAI) provides guidance on probiotics and health claims in the Irish context [9].
5) How DSF relates to VSL#3, CDS22-formula, and Vivomixx
The De Simone Formulation is the original 8-strain probiotic mixture developed by Professor Claudio De Simone. It was sold as VSL#3 until 2016. After 2016, the product sold under the VSL#3 brand name no longer contained this formulation [1]. Products such as CDS22-formula and certain Vivomixx formulations are described by their manufacturers as containing the De Simone Formulation or an 8-strain mixture intended to match it. Verification should be based on the strain list rather than brand name alone.
6) Strain composition comparison table (Ireland-facing reference)
This table is an identity aid. It is not clinical advice and it does not evaluate efficacy. Always verify against up-to-date manufacturer documentation and the product labelling used in Ireland.
| Product name (as commonly referenced) | Number of strains | Matches the original DSF 8-species list above? | Notes for interpretation | Availability (general) |
|---|---|---|---|---|
| CDS22-formula | 8 | Presented as matching DSF (check strain list) | Verify by comparing the product strain list with the DSF 8-species reference list and current documentation. | Varies by retailer/distributor |
| VSL#3 (current) | 8 | No (not DSF after 2016, per ECCO statement) | Brand name continuity does not equal formulation continuity. | Varies by retailer |
| Vivomixx (manufacturer describes certain formulations as DSF) | 8 | Check by strain list | Product naming and variants can differ by market. Confirm the exact strain list on current documentation. | Varies by product/variant |
| Vivomixx Neo | Varies | Check by strain list | Different product line naming exists in different markets. Confirm the exact strain list on current documentation. | Varies |
In practical terms: CDS22-formula is presented as matching the original 8-strain composition; current VSL#3 does not contain the De Simone Formulation [1]; Vivomixx products can vary by line and should be checked by strain list.
7) Is the original De Simone Formulation available in Ireland in 2026?
In Ireland in 2026, pre-2016 “VSL#3” clinical references relate to the De Simone Formulation (DSF), while products sold as VSL#3 after 2016 do not contain DSF, per ECCO’s statement [1]. Availability depends on formulation identity rather than brand name and should be verified by strain list and current manufacturer documentation.
For traceability, retain product documentation (strain list and labelling) alongside the primary sources in section 9.
8) FAQs (Ireland)
Is CDS22-formula the same as VSL#3?
“VSL#3” is a brand name, and the evidence question depends on which formulation a study or guideline reference is discussing. ECCO states that until 2016 the De Simone Formulation (DSF) was sold as VSL#3, and that after 2016 the VSL#3 product no longer contains DSF [1]. If you are trying to match older evidence that referred to VSL#3, verify whether the product matches DSF by strain list.
Why do older studies reference VSL#3?
Many clinical studies were conducted before 2016 when DSF was sold under the VSL#3 name. That is why “VSL#3” appears in older papers and summaries. ECCO’s official statement clarifies that VSL#3 references in its 2017 guidelines exclusively endorse DSF supported by scientific evidence, because post-2016 VSL#3 does not contain DSF [1].
Is Vivomixx the same as the original De Simone Formulation?
Vivomixx materials describe certain formulations as “De Simone Formulation” and describe an 8-strain high-potency mixture. Product lines and naming can differ by market. The safest method is an identity check: compare the product strain list to the DSF 8-species reference list and verify against current manufacturer documentation.
What does “high strength probiotics” mean in Ireland?
In Ireland, “high strength” is commonly used as a marketing label for higher potency products, often described using CFU numbers. CFU is a label measure, but a higher CFU number is not automatically “better”. For general supplement safety, the HSE advises speaking with a GP or healthcare professional about supplements where appropriate [8].
How can Irish patients verify formulation identity?
Use a three-step check. First, identify the strain list in the product documentation. Second, confirm whether the evidence you care about relates to DSF (for example, pre-2016 VSL#3 references). Third, keep a record of manufacturer documentation alongside the primary sources linked below for traceability.
9) Source documentation
These sources support verification of the key factual distinctions used on this page. Links open external sites.
- [1] ECCO official statement (Oct 2023) clarifying DSF vs post-2016 VSL#3:
https://ecco-ibd.eu/publications/news/issues/2023/volume-18-issue-3/ecco-official-statement - [2] US Fourth Circuit decision (FindLaw mirror): De Simone LLC v. VSL (2021):
https://caselaw.findlaw.com/court/us-4th-circuit/2112681.html - [3] US Fourth Circuit (Justia) decision (2022): Claudio De Simone v. VSL Pharmaceuticals, Inc.:
https://law.justia.com/cases/federal/appellate-courts/ca4/20-1846/20-1846-2022-06-07.html - [4] Peer-reviewed overview describing the historic 8-strain VSL#3 mixture (PMC):
https://pmc.ncbi.nlm.nih.gov/articles/PMC7190945/ - [5] Example product-card PDF referencing high-potency formats (Vivomixx):
https://www.vivomixx.eu/wp-content/uploads/2024/06/68009-43_vivomixx_Product_card_EN_20240417_v2.pdf - [8] HSE (Ireland) vitamins and minerals page (supplement safety, talk to a GP/healthcare professional):
https://www2.hse.ie/conditions/vitamins-and-minerals/iodine/ - [9] Food Safety Authority of Ireland (FSAI): probiotic health claims and consumer/business guidance:
https://www.fsai.ie/business-advice/industry-specific-guidance/probiotic-health-claims
10) Editorial transparency
Author: Probiotic.ie Editorial Team
Market focus: Republic of Ireland
Published: 2026-02-23
Last updated: 2026-02-23
Editorial policy: This page summarises publicly available clinical and legal context and links to primary sources where possible. It does not provide medical advice, diagnosis, or treatment recommendations. For clinical decisions, consult a qualified healthcare professional.
Disclosure (traceability): Probiotic.ie distributes CDS22-formula in the Republic of Ireland and can provide distribution documentation on request for verification purposes. This disclosure is provided for supply-chain transparency only.