Strain identity decides everything: ATCC PTA 6475 carries the published research, while LRDR is a separate proprietary strain with no such evidence.
The useful part of any L. reuteri strain guide comes down to one line on the bottle: the strain code. A species name is cheap to print. A strain designation means a manufacturer can point to a specific organism and a specific body of research — and when that code is missing, nothing connects the capsule to the studies you read about.
Here is what ATCC PTA 6475 has been studied for, where LRDR™ stands, and the lines worth checking before you pay.
What Strain Of L. Reuteri Is Actually In The Bottle?
L. reuteri is the species; ATCC PTA 6475, DSM 17938, and LRDR™ are strains inside it, and the evidence attached to each one is different.
The naming confuses people first. The current taxonomic name is Limosilactobacillus reuteri, so a bottle marked Lactobacillus reuteri holds the same organism under an older name. The rename says nothing about strain.
ATCC PTA 6475 is a publicly identified strain, which is why outside labs can study it and compare notes. DSM 17938 is a separate strain that appeared as the partner in a human IBS trial. LRDR™ is a proprietary, human-origin strain sold in MyReuteri products, and the available product information does not establish that LRDR™ is ATCC PTA 6475 — nor does it inherit 6475’s research.
| Strain Or Label Term | What It Means | What It Cannot Tell You |
|---|---|---|
| ATCC PTA 6475 | Publicly identified strain with published preclinical and human research | That the bottle holds the studied dose |
| DSM 17938 | The partner strain in the 14-week IBS trial | Anything about 6475 used alone |
| LRDR™ | Proprietary human-origin strain sold as MyReuteri | That it matches ATCC PTA 6475 |
| “L. reuteri” alone | Species name only | Which strain, or which study applies |
| CFU at manufacture | Potency on the day it was made | Potency at expiration |
| Heat-killed cells | Non-viable cells, sometimes sold as postbiotics | A live-cell result |
| Starter sachet | Fermented dairy starter with 13 g FOS and inulin | A capsule dose |
ATCC PTA 6475 Evidence: Where The Research Stops
ATCC PTA 6475 has published research, but most of it is preclinical or tied to a combination product, and none of it proves a general health benefit.
- Baylor College of Medicine’s Britton lab describes work in which the strain reduced bone loss in a mouse osteoporosis model, and says that work fed into human clinical trial and product development. Mouse data is a starting point, not a human result.
- A 2024 animal study found both live and heat-killed ATCC PTA 6475 preserved bone volume in ovariectomized mice. Preclinical again — and a reminder that live cells and heat-killed preparations are not interchangeable.
- The human trial quoted most often tested ATCC PTA 6475 combined with DSM 17938 in adults aged 18 to 65 with moderate-to-severe IBS, per the 14-week randomized IBS trial. Dosing was twice daily, with improvement showing from week 6.
- Those figures belong to the tested combination and protocol, not to every 6475 bottle and not to LRDR™.
- A 2025 pilot gave 10 adults aged 50 to 69 a total of 10 billion live ATCC PTA 6475 cells daily for 12 weeks and reported changes in body-fat percentage, blood pressure, and some inflammatory markers. Ten people, no placebo arm — that needs confirmation.
L. Reuteri Strain Labels: What Decides The Purchase
Match the strain code to the reason you are taking it, and treat any bottle that prints only the species name as unverifiable.
Four label lines do most of the work:
- Exact strain identifier: ATCC PTA 6475, DSM 17938, or LRDR™.
- CFU amount, plus whether it is guaranteed through expiration or measured at manufacture. Ten billion CFU of L. reuteri is not ten billion CFU of ATCC PTA 6475.
- Serving size, storage, expiration date, lot number, allergen statement, and supplement facts.
- Live cells versus heat-killed, and starter sachet versus capsule — different products, different doses.
MyReuteri shows why the last point matters. MyReuteri Starter Culture Complete pairs LRDR™ with 13 g of FOS and inulin per sachet for fermented dairy — a starter, not a capsule. Capsule listings come in 10, 20, and 50 billion CFU, and one marketplace listing for MyReuteri 10 Billion CFU names LRDR™, an FOS prebiotic, and 30 vegan capsules. No verified current US retail price appeared in the official sources, so check the live listing.
If you would rather start from a shortlist, the L. reuteri supplement picks we tested are a faster place to begin.
People who are immunocompromised or seriously ill, people with a central venous catheter, and anyone weighing use during pregnancy or for an infant should get clinician guidance first; the published sources offer no blanket assurance for those groups.
The decision stays short: pick the strain that matches your reason for taking it, confirm the code and CFU count are printed where you can trace them, and leave anything that stops at the species name on the shelf.
Common Questions
Is LRDR™ The Same Strain As ATCC PTA 6475?
No. LRDR™ is a proprietary, human-origin strain of L. reuteri, while ATCC PTA 6475 is a publicly identified strain that outside labs have studied. The available product information for LRDR™ does not establish that the two are identical, so results from 6475 trials should not be applied to LRDR™ products unless the manufacturer documents strain identity or runs its own study.
What CFU Count Should I Look For?
There is no single established dose. In a small 2025 pilot, adults took a total of 10 billion live ATCC PTA 6475 cells daily for 12 weeks, which describes that study rather than a recommendation. What matters more is that the label ties a CFU number to a named strain and says whether that number is guaranteed through expiration or only measured at manufacture.
Do Heat-Killed L. Reuteri Products Work The Same Way?
Not automatically. A 2024 mouse study found that both live and heat-killed ATCC PTA 6475 preserved bone volume in ovariectomized animals, which suggests the non-viable form is worth studying — not that it substitutes for live cells. Different preparations, doses, and strains behave differently, and human comparisons are limited, so treat a heat-killed product as its own purchase decision.
Sources
- Baylor College of Medicine. “Limosilactobacillus reuteri as a Key Therapeutic Bacterial Species” Source for the mouse bone-loss work and its path to human trials.
- National Library of Medicine / PMC. “Viable and heat-killed ATCC PTA 6475 in ovariectomized mice” Source for the 2024 preclinical bone-volume findings.
- National Library of Medicine / PMC. “Randomized trial of ATCC PTA 6475 with DSM 17938 in IBS” Source for the 14-week protocol and the 80% versus 43% results.