The benefits probiotics are sold to men for, graded against the trials
The home page carries the verdict and what to buy. This is the proof behind it: every outcome men search for with the best grade any named strain earns, every strain with a claim in this category with the trial behind it, and one page per outcome where that grade is argued rather than asserted. Every passage here has its own permanent link, because these pages exist to be quoted.
The finding, in full
Four paragraphs of § The answer are on the home page. The three below are the rest of it, and they moved here rather than being repeated there: they are evidence about the evidence, and this is the page that carries the evidence. The list at the end is the shortest true summary of what this site found.
- No outcome anywhere reaches Grade A at strain level. Not one strain has two independent RCTs, with at least one non-owner replication, on a clinical endpoint in the indication it is sold for. Not one.
- Zero trials have ever shown a probiotic benefit that is larger in men than in women. The only two sex-comparative analyses that exist both run the other way: weight loss significant in women (P=0.02) and not in men (P=0.53) for L. rhamnosus CGMCC1.3724 (PMID 24299712 (opens in a new tab)), and amino-acid response "greater… in women when compared to… men" for B. coagulans GBI-30, 6086 (PMID 33110439 (opens in a new tab)).
- Where a strain does earn a grade, you usually cannot buy it at the dose that was tested. Of 27 products we took apart at label level, 25 (92.6%) have no published trial of the thing in the bottle. Of the two that do, only one was tested at the dose on its own label.
The ranking, in one table
Every outcome men search for, the best grade any named strain earns for it, and whether that strain is buyable in this market at the dose that was studied.
| # | Outcome | Best grade at strain level | The strain, and the trial behind it | Buyable at the dose that was studied? |
|---|---|---|---|---|
| 1 | Diarrhoea while taking antibiotics | Grade B for Diarrhoea while taking antibiotics — one adequately powered strain-level trial | Saccharomyces boulardii — AAD in adults, 17.4%→8.2%, RR 0.49 (0.38–0.63), 15 RCTs, n=3,114 (PMID 26216624 (opens in a new tab)) | No — no S. boulardii single-organism product in our teardown set; the two products containing it bury it in a blend with no per-strain quantity |
| 2 | Staying on H. pylori eradication therapy | Grade B for Staying on *H. pylori* eradication therapy — one adequately powered strain-level trial | S. boulardii — treatment discontinuation RR 0.33 (0.16–0.69), moderate certainty | No |
| 3 | IBS pain and bloating (diagnosed IBS) | Grade C for IBS pain and bloating (diagnosed IBS) — one positive trial with a material design defect | Lactiplantibacillus plantarum 299v (DSM 9843); Bacillus coagulans Unique IS2 (MTCC 5260) | Partly — 299v sits in one product inside a proprietary blend, so its dose is unknowable; Unique IS2 is in none |
| 4 | Weight-regain prevention after dieting | Grade C for Weight-regain prevention after dieting — one positive trial with a material design defect | Pasteurised Akkermansia muciniphila MucT (PMID 42120725 (opens in a new tab); NCT05417360 (opens in a new tab)) | No — the product on sale is live, under a house code with zero published literature, and the live arm was null |
| 5 | Visceral fat | Grade C for Visceral fat — one positive trial with a material design defect | Lactobacillus gasseri BNR17 at 10¹⁰ CFU/day, −21.6 cm² vs placebo, P=0.012 (PMID 29688793 (opens in a new tab)) | No — absent from the teardown set |
| 6 | LDL cholesterol | Grade C for LDL cholesterol — one positive trial with a material design defect | Limosilactobacillus reuteri NCIMB 30242 (PMID 22067612 (opens in a new tab); PMID 22990854 (opens in a new tab)) | No — absent from the market universe entirely |
| 7 | Semen parameters in diagnosed male infertility | Grade C for Semen parameters in diagnosed male infertility — one positive trial with a material design defect | FamiLact® (no strain designators exist); L. paracasei B21060 in a four-ingredient synbiotic | No — neither is a US retail men's probiotic, and EAU 2025 recommends against routine use |
| 8 | Endurance / time to exhaustion | Grade C for Endurance / time to exhaustion — one positive trial with a material design defect | L. plantarum TWK10 | No — absent from the teardown set; the one trial without strain-owner authorship found no effect in the probiotic-only arm |
| 9 | Protein/amino-acid kinetics, subjective recovery | Grade C for Protein/amino-acid kinetics, subjective recovery — one positive trial with a material design defect | B. coagulans GBI-30, 6086 — and the effect was larger in women (PMID 33110439 (opens in a new tab)) | No |
| 10 | Colds, and antibiotic use for colds | Grade D for Colds, and antibiotic use for colds — class-level pooled evidence only | Class-level only — RR 0.76 (0.67–0.87); antibiotic use RR 0.58 (0.42–0.81) (PMID 36001877 (opens in a new tab)) | N/A — a class effect points at no product |
| 11 | C. difficile diarrhoea during antibiotics | Grade D for *C. difficile* diarrhoea during antibiotics — class-level pooled evidence only | Class-level only — RR 0.50 (0.38–0.64), NNT 65 (48–97), low certainty (PMID 40931979 (opens in a new tab)) | N/A |
| 12 | Regularity and constipation | Grade D for Regularity and constipation — class-level pooled evidence only | Class-level only; the strain marketed hardest for "regularity" failed both of its clinical-endpoint trials | N/A |
| 13 | Testosterone and male hormones | Grade F for **Testosterone and male hormones** — nothing qualifies | — | Nothing qualifies |
| 14 | Prostate, BPH, LUTS, PSA | Grade F for **Prostate, BPH, LUTS, PSA** — nothing qualifies | — | Nothing qualifies |
| 15 | Chronic prostatitis (probiotic alone) | Grade F for **Chronic prostatitis (probiotic alone)** — nothing qualifies | — | Nothing qualifies |
| 16 | Erectile and sexual function | Grade F for **Erectile and sexual function** — nothing qualifies | — | Nothing qualifies |
| 17 | Male urinary tract infection | Grade F for **Male urinary tract infection** — nothing qualifies | — | Nothing qualifies |
| 18 | Balanitis / balanoposthitis | Grade F for **Balanitis / balanoposthitis** — nothing qualifies | — | Two records exist in the entire literature; one is a 1990 veterinary paper about ganders (PMID 2082630 (opens in a new tab)) |
| 19 | Mood, stress and anxiety in men | Grade F for **Mood, stress and anxiety in men** — nothing qualifies | — | Nothing qualifies |
| 20 | Blood sugar / HbA1c | Grade F for **Blood sugar / HbA1c** — nothing qualifies | — | Nothing qualifies |
| 21 | Colorectal cancer incidence | Grade F for **Colorectal cancer incidence** — nothing qualifies | — | Never reduced by any probiotic in any human trial (PMID 38126945 (opens in a new tab)) |
| 22 | Any benefit specific to men — larger in men than in women | Grade F for **Any benefit specific to men** — larger in men than in women — nothing qualifies | — | Zero trials. Not one strain, not one outcome, not one trial. |
How the grades work
| Grade | What a strain has to have to earn it |
|---|---|
| Grade A — replicated, at least one independent trial | Two or more RCTs of the same named strain at a stated dose, consistent direction, at least one without strain-owner authorship, pooled or independently replicated, on a clinical endpoint. |
| Grade B — one adequately powered strain-level trial | One adequately powered RCT of a named strain that met a pre-registered primary endpoint, or strain-level pooling across multiple RCTs, certainty no lower than "low", no fatal design defect. |
| Grade C — one positive trial with a material design defect | One positive RCT of a named strain with a material design defect — manufacturer-run and unreplicated, a secondary endpoint, a co-intervention that cannot be dismantled, or a surrogate endpoint. |
| Grade D — class-level pooled evidence only | Class-level pooled evidence only. Real, but it transfers to no product on a shelf, because the pool contains dozens of different organisms. |
| Grade F — nothing qualifies | Nothing qualifies. Searched, and either empty or refuted. |
Grades are assigned strain-first because that is the unit the evidence exists in — and the unit the FTC's own substantiation standard uses. Example 36 of the FTC's Health Products Compliance Guidance (December 2022) holds that a different strain, a different format and a different population each independently defeat evidence transfer.
The strain × outcome table
This is the core asset: every strain with a claim in the men's category, the outcome it is sold for, its grade, the trial behind it, the sample size, whether men were actually studied, and who paid. Sorted by grade.
| Strain | Outcome it is sold for | Grade | The trial | n | Were men actually studied? | Who paid |
|---|---|---|---|---|---|---|
| Saccharomyces boulardii (CNCM I-745 where stated) | AAD in adults | Grade B for AAD in adults — one adequately powered strain-level trial | Pooled, 15 RCTs (PMID 26216624 (opens in a new tab)) | 3,114 | Mixed; no sex-stratified efficacy analysis exists in this field | Multiple sponsors; pooled |
| S. boulardii | Discontinuation of H. pylori eradication therapy | Grade B for Discontinuation of H. pylori eradication therapy — one adequately powered strain-level trial | Pooled, RR 0.33 (0.16–0.69), moderate certainty | — | Mixed | Pooled |
| L. plantarum 299v (DSM 9843) | IBS pain, bloating | Grade C for IBS pain, bloating — one positive trial with a material design defect | Ducrotté 2012 (PMID 22912552 (opens in a new tab)) | 214 | Yes — 70.6% male, the second most male-heavy digestive RCT on record | "Supported by Rosell-Lallemand Institute, France and Probi AB, Sweden" |
| B. coagulans Unique IS2 (MTCC 5260) | IBS pain, stool form | Grade C for IBS pain, stool form — one positive trial with a material design defect | Madempudi 2019 (PMID 31434935 (opens in a new tab)) | 136 randomised / 108 PP | Yes — 72.22% male, the most male-heavy digestive RCT on record | "Fully funded by Unique Biotech Ltd"; all authors or their organisations compensated |
| B. longum subsp. longum 35624 | IBS global symptoms | Grade C for IBS global symptoms — one positive trial with a material design defect | Whorwell 2006 (PMID 16863564 (opens in a new tab)); Ringel 2016 (PMID 27845337 (opens in a new tab)) | 362; 302 | Pivotal trial enrolled women only; the general-population trial was 79% female and missed its primary endpoint | Manufacturer-sponsored |
| B. coagulans MTCC 5856 (LactoSpore®) | IBS | Grade C for IBS — one positive trial with a material design defect | Two manufacturer-run pilots | 76 combined | Not stratified | Manufacturer-run; one confounded by concurrent standard care |
| S. cerevisiae CNCM I-3856 | IBS | Grade C for IBS — one positive trial with a material design defect | Named efficacious, 2026 strain-specific MA (PMID 41682832 (opens in a new tab)) | — | Not stratified | Counter-datum: 32.2% vs 26.9%, ns, in ACG's own review |
| L. rhamnosus GG (ATCC 53103) | IBS | Grade C for IBS — one positive trial with a material design defect | Named efficacious, 2026 MA (PMID 41682832 (opens in a new tab)) | — | Not stratified | Mixed record; one clean null on bloating |
| Pasteurised A. muciniphila MucT | Weight-regain prevention | Grade C for Weight-regain prevention — one positive trial with a material design defect | PMID 42120725 (opens in a new tab) · NCT05417360 (opens in a new tab) | 90 | Sex breakdown not retrievable | Sponsored by The Akkermansia Company SA; CTO (co-founder), CMO and an employee are co-authors; four authors are patent inventors |
| L. gasseri BNR17 | Visceral fat | Grade C for Visceral fat — one positive trial with a material design defect | PMID 29688793 (opens in a new tab) | 90 | Sex not reported | Funding and COI unverified; a second BNR17 trial was null (PMID 23560206 (opens in a new tab)) |
| Hafnia alvei HA4597 | Weight loss | Grade C for Weight loss — one positive trial with a material design defect | PMID 34205871 (opens in a new tab) | 236 randomised / 230 ITT | 103 men / 127 women — and the published male subset was null (p=0.12) | Funded by TargEDys SA |
| L. reuteri NCIMB 30242 | LDL cholesterol | Grade C for LDL cholesterol — one positive trial with a material design defect | PMID 22067612 (opens in a new tab); PMID 22990854 (opens in a new tab) | 114; 127 completers | Not stratified; the only sex-stratified lipid analysis in this focus set trends toward women (P=0.06, PMID 29228000 (opens in a new tab)) | Sponsor group; never independently replicated in 14 years; two completed LDL-primary trials (n=150, n=111) have never reported results |
| L. plantarum TWK10 | Endurance | Grade C for Endurance — one positive trial with a material design defect | Six RCTs, TTE 1.24–1.58× placebo | — | Two men-only datasets (n=30, p=0.0028; male clinical arm 1.27×, p<0.01) | Every trial showing a standalone effect carries SYNBIO TECH INC. authorship; the one non-owner trial (NCT06285578 (opens in a new tab)) found no effect in the probiotic-only arm |
| B. coagulans GBI-30, 6086 (BC30) | Recovery, muscle damage | Grade C for Recovery, muscle damage — one positive trial with a material design defect | PMID 27547577 (opens in a new tab); PMID 33110439 (opens in a new tab) | 29; 30 | Men-only crossover for the damage trial | "Supported by Ganeden Biotech Inc"; two authors employees of Increnovo LLC. The paper's title claims damage reduction; its results section reports a trend at p<0.08. The amino-acid effect was larger in women |
| Lab4 (CUL60 + CUL21 + CUL20 + CUL34) | Exercise GI symptoms | Grade C for Exercise GI symptoms — one positive trial with a material design defect | PMID 30982100 (opens in a new tab) | 24 | Recreational runners, not stratified | "The authors report no conflict of interest" — but the same blend was null in PLACIDE, n=2,981 (PMID 23932219 (opens in a new tab)) |
| FamiLact® (7 organisms + FOS, no designators exist) | Semen parameters | Grade C for Semen parameters — one positive trial with a material design defect | PMID 33842820 (opens in a new tab); PMID 41625341 (opens in a new tab); PMID 38152072 (opens in a new tab) | 47 analysed; 110; 78 | Yes — three men-only randomised trials | Academic (AJA University; Iranian registries). No strain designators anywhere in the public record, so nothing transfers to any other product |
| L. paracasei B21060 (Flortec) | Semen parameters, hormones | Grade C for Semen parameters, hormones — one positive trial with a material design defect | Maretti & Cavallini 2017 (PMID 28245352 (opens in a new tab)) | 41 | Yes — men only, iOAT, 6 months | Pilot; non-parametric within-group comparisons; the active arm is a four-ingredient synbiotic, so nothing is attributable to the strain |
| L. paracasei Shirota (YIT 9029) | Colds | Grade C for Colds — one positive trial with a material design defect | PMID 26419583 (opens in a new tab) | 96 | Yes — the only men-only clinical URTI trial that exists | "All of the authors are employed by the Yakult Honsha." Comparator was control milk, not placebo; blinding is never claimed; no registration; severity was null (P=0.966); the same lead author's positive athlete result failed to replicate at 3× the sample size (PMID 27294502 (opens in a new tab)) |
| B. animalis (species level) | Colds | Grade D for Colds — class-level pooled evidence only | Network MA, 107 trials / 101,751 adults (PMID 40969681 (opens in a new tab)) | 101,751 | No sex/gender subgroup analysis | Independently funded (Ningbo CDC; Zhejiang programme) |
| Probiotics as a class | Colds; antibiotic use for colds | Grade D for Colds; antibiotic use for colds — class-level pooled evidence only | Cochrane 2022 (PMID 36001877 (opens in a new tab)) | 6,950 | Not stratified | "Fifteen studies received funding… 10 trials received funding from the company that produced the probiotics" |
| Probiotics as a class | CDAD during antibiotics | Grade D for CDAD during antibiotics — class-level pooled evidence only | Cochrane 2025 (PMID 40931979 (opens in a new tab)) | 13,179 | Not stratified | "We noted authors' affiliation with a probiotic company and financial support received from probiotic companies in 28 studies" |
| Probiotics as a class | Blood pressure | Grade D for Blood pressure — class-level pooled evidence only | PMID 25047574 (opens in a new tab) | 9 trials | Not stratified | No effect below 10¹¹ CFU/day or under 8 weeks |
| Probiotics as a class | Exercise performance | Grade D for Exercise performance — class-level pooled evidence only | PMID 35276980 (opens in a new tab) | 12 pooled / 232 | Male subgroup SMD 0.30 (0.04–0.56) — one of the very few pooled male estimates anywhere, and it is small | — |
| L. reuteri ATCC PTA 6475 | Testosterone | Grade F for Testosterone — nothing qualifies | PMID 38770015 (opens in a new tab) · NCT04577625 (opens in a new tab) | 57 randomised | Yes — men aged 50–65, testosterone as the prospectively registered primary endpoint | Lead sponsor BioGaia AB, study class INDUSTRY; co-author Jakob Axelsson is a BioGaia employee. It failed at both 1×10⁹ and 1×10¹⁰ CFU/day |
| B. subtilis DE111 | Testosterone, body composition, performance | Grade F for Testosterone, body composition, performance — nothing qualifies | PMID 30049931 (opens in a new tab) | 25 | Yes — men only, Division I baseball | "No effect on body composition, performance, hormonal status, or gut permeability"; the marketed body-fat claim comes from a 23-person women-only trial at 5× the dose (PMID 33105368 (opens in a new tab)) |
| B. longum novaBLG1 (DSM 34338) + B. psychraerophilum Q5 (DSM 33131) | Prostate | Grade F for Prostate — nothing qualifies | PMID 39594064 (opens in a new tab) | Zero humans, zero animals | Never given to a single human being | One author employed by Noivita Srls, another its co-founder; strains donated by Probionova SA |
| L. rhamnosus GR-1 + L. reuteri RC-14 | Male UTI | Grade F for Male UTI — nothing qualifies | ProSCIUTTU (PMID 30814670 (opens in a new tab)) | 207 | Yes — 163/207 = 79% male, the most male-dominant UTI trial that exists | NHMRC (government); product supplied by Chr. Hansen. HR 0.67 (0.39–1.18), P=0.17 — primary not met |
| LGG + BB-12 | Male UTI | Grade F for Male UTI — nothing qualifies | Same trial (PMID 30814670 (opens in a new tab)) | 207 | 79% male | HR 1.29 (0.74–2.25), P=0.37 — the point estimate favours placebo |
| L. paracasei CNCM I-1572 (L. casei DG®) | Prostatitis, IPSS, IIEF | Grade F for Prostatitis, IPSS, IIEF — nothing qualifies | Vocca 2025 (PMID 39858898 (opens in a new tab)) | 24 (12/12) | Yes — men only, 18–55 | IPSS p=0.546; NIH-CPSI p=0.187. Post-hoc power 0.65; no sample-size calculation; no trial registration anywhere in the paper; product and placebo supplied with support from Alfasigma S.p.A., the manufacturer |
| L. plantarum HEAL9 (DSM 15312) + 8700:2 (DSM 13434) | Colds | Grade F for Colds — nothing qualifies | PMID 33296464 (opens in a new tab) · NCT02013934 (opens in a new tab) | 898 | 37.1% / 34.7% male, no sex-stratified analysis | Four of five authors are employees of Probi AB, which owns the strains. Severity numerically worse on probiotic (P=0.69) |
| B. animalis subsp. lactis Bl-04 (ATCC SD5219) | Colds | Grade F for Colds — nothing qualifies | PMID 34927036 (opens in a new tab) · NCT02679807 (opens in a new tab) | 334 randomised / 232 analysed | Not stratified | Sponsor Danisco Sweeteners Oy / IFF; several authors hold a patent pending based on these results. Missed its pre-registered primary; the point estimate favours placebo |
| B. animalis subsp. lactis BB-12 | Regularity, bloating | Grade F for Regularity, bloating — nothing qualifies | PMID 26382580 (opens in a new tab) | 1,248 randomised / 1,000 PP | 20.3–20.4% men, and randomisation was stratified by sex — so the sex comparison was pre-defined, not post hoc. It was null: P=0.44 | "Funded in full by Chr. Hansen A/S"; four employee authors. Missed both pre-specified primaries |
| B. animalis subsp. lactis HN019 (DR10) | Regularity | Grade F for Regularity — nothing qualifies | PMID 29227175 (opens in a new tab); PMID 40320938 (opens in a new tab) | 228; 8 weeks | Not stratified | Both larger trials failed; authors at DuPont and at International Flavors & Fragrances respectively. Zero IBS trials exist for this strain |
| L. rhamnosus CGMCC1.3724 | Weight loss | Grade F for Weight loss — nothing qualifies F in men | PMID 24299712 (opens in a new tab) | 125 analysed (48 men, 77 women) | Yes, and stratified: women lost more weight than placebo (P=0.02); men did not (P=0.53) | Sponsored by The Nestlé Research Center; six of seventeen authors are Nestlé staff, while the paper declares "None of the authors has any conflicts of interest" |
| L. paragasseri SBT2055 | Visceral fat | Grade F for Visceral fat — nothing qualifies F as evidence | Two trials | — | No sex-stratified result ever published | Both report within-group change only; neither abstract reports a between-group comparison of the change |
| L. plantarum ECGC 13110402 (LPLDL®) | Cholesterol | Grade F for Cholesterol — nothing qualifies | PMID 29228000 (opens in a new tab) · NCT03263104 (opens in a new tab) | 46 completers | 5 men on active | Null on every whole-population lipid and BP endpoint except a trivial HDL-C rise. The authors disowned their own headline: "No group relevance should therefore be attributed to this effect." |
| WBF-011 (Pendulum Glucose Control) | Blood sugar | Grade F for Blood sugar — nothing qualifies | PMID 32675291 (opens in a new tab) · NCT03893422 (opens in a new tab) | ITT 23 | 13 female → ~10 men | CRP co-primary failed outright (p=0.6797); glucose co-primary p=0.0500 one-sided; A1c a secondary at p=0.0540. All 17 authors are employees and stock/stock-option shareholders of Pendulum Therapeutics. The confirmatory A1c-primary trial was terminated |
| L. helveticus R0052 + B. longum R0175 | Mood, stress | Grade F for Mood, stress — nothing qualifies F in men | PMIDs 37049546 (opens in a new tab), 38732635 (opens in a new tab), 28068788 (opens in a new tab) | 135; 116; 79 | The largest was 14.7% male (81 F : 14 M). No men-only trial and no sex-stratified mood analysis has ever been published | Product supplied by Sanprobi Sp. z o.o.; the largest trial was funded by the Medical University of Lodz with no competing interests declared |
| B. longum 1714™ (NCIMB 41676) | Mood, stress | Grade F for Mood, stress — nothing qualifies | PMID 42060410 (opens in a new tab); PMID 34589719 (opens in a new tab) | 168; 20 | The men-only randomised trial (20 male students) was null for stress, depression and every cognitive measure; sleep improved | — |
| L. plantarum PS128 | Stress | Grade F for Stress — nothing qualifies | PMID 33842519 (opens in a new tab) · NCT04452253 (opens in a new tab) | 36 | Not stratified | Open-label, single-arm, not an RCT. Four authors are Bened Biomedical employees, one holds stock. Carved out of a four-arm registration with a placebo that has never posted results |
| CBM588 | Cancer support | Grade F for Cancer support — nothing qualifies | PMIDs 35228755 (opens in a new tab), 38942995 (opens in a new tab) | 30 each | Kidney cancer | Both Nature Medicine papers missed their primary endpoint; both open-label phase 1; manufacturer ties and a cancer-use patent among the authors |
| Saw palmetto (the non-bacterial active in "prostate" probiotics) | Prostate, LUTS | Grade F for Prostate, LUTS — nothing qualifies | Cochrane (PMID 23235581 (opens in a new tab)); CAMUS (PMID 21954478 (opens in a new tab)) | 5,666; 369 | Yes — men only | Publicly funded (NIH R01 DK063300), COI "None declared." AUA symptom score MD 0.25 (−0.58 to 1.07); in CAMUS at 320→960 mg/day the group mean difference favoured placebo (one-sided P=0.91). Men's probiotics dose it at 80–303 mg — a quarter of a dose that already failed |
| Cranberry (in men's "urinary" probiotics) | Male UTI | Grade F for Male UTI — nothing qualifies F in men | Cochrane 2023 (PMID 37947276 (opens in a new tab)) | 8,857 randomised | No male-only subgroup exists. The only subgroup including men — elderly institutionalised men and women — showed RR 0.93 (0.67–1.30) | — |
H. pylori, colds, exercise, weight, cholesterol and mood — the short versions
Six paragraphs, four of which are now whole outcome pages. The two with no page of their own are below, complete and unaltered. Nothing in this section was dropped and no paragraph is in two places: this is a split by paragraph, never by sentence.
For H. pylori eradication, the most clinically meaningful result is that fewer people quit the therapy. S. boulardii reduces treatment discontinuation at RR 0.33 (95% CI 0.16–0.69), moderate certainty — that is Grade B. Diarrhoea during eradication: RR 0.33 (0.23–0.47), GRADE low, with a comparator of "standard eradication regimen" rather than placebo, so Grade C. L. reuteri Gastrus (DSM 17938 + ATCC PTA 6475) gives the strongest placebo-controlled eradication estimate: ITT 80.0% versus 72.6%, RR 1.10 (1.03–1.17), NNT 14, 8 RCTs / 1,087 — Grade C. Probiotic monotherapy achieves 16.8% total eradication, and 0% in one dedicated trial. Maastricht VI grades both of its probiotic statements as weak recommendations and places them in the microbiota working group, not the treatment working group; ACG 2024 Recommendation 12 is an explicit non-endorsement: "There is insufficient evidence to suggest that the use of probiotic therapy improves the efficacy or tolerability of H. pylori eradication therapy." And the stronger argument than any of the above: every well-conducted placebo-controlled RCT on a modern backbone — 14-day quadruple, bismuth quadruple, or vonoprazan-based — is null on eradication, with a 41,298-patient European registry analysis null overall (89.6% versus 89.6%, p=0.495).
For training and endurance, the pooled male estimate exists and it is small: SMD 0.30 (95% CI 0.04–0.56) (PMID 35276980 (opens in a new tab)) — one of very few pooled male-subgroup estimates anywhere in this literature. TWK10 has the most consistent endurance signal, and every trial showing a standalone effect carries strain-owner authorship, while the one trial without strain-owner involvement attributed its time-to-exhaustion gain to HIIT with no significant effect in the probiotic-only arm. For exercise-induced GI distress, the best pooled evidence rates effects "outside of clinical relevance", GRADE Low, with no study reaching the i-FABP clinical-relevance threshold (PMID 39940302 (opens in a new tab)). The IOC's good-evidence-for-performance list is caffeine, creatine monohydrate, nitrate, sodium bicarbonate and possibly beta-alanine — probiotics appear twice in that consensus statement, neither time in a performance context (PMID 29540367 (opens in a new tab)). And one trial ran against the probiotic: 99 competitive cyclists, "The number and duration of mild gastrointestinal symptoms were ~2-fold greater in the probiotic group" (PMID 21477383 (opens in a new tab)).
The other four paragraphs of this section are the whole of three pages:
- Colds, and antibiotic use for colds
- Weight and body composition, and cholesterol — two paragraphs
- Mood, stress and sleep in men
One page per outcome
Each page carries that outcome's copy as published — the trials, the effect sizes, the funding and the caveat that travels with each claim — with the answer first and a permanent link on every passage. The grade beside each one is the best grade any named strain earns for that outcome, taken from the table above. 3 of them are the paragraphs split out of § The short versions rather than sections of their own, and each says so in its first line.
- Probiotics and testosterone in men: the whole chain, end to end Grade F for Testosterone — nothing qualifies The claim starts in one mouse study, and the same strain then failed in men in a trial run by the company that sells it. Every link in the chain.
- Probiotics for the prostate: every trial, and what none of them shows Grade F for Prostate and BPH — nothing qualifies No human randomised trial of any probiotic strain in men with benign prostatic hyperplasia is indexed in PubMed. What exists instead, in full.
- Probiotics and erectile function Grade F for Erectile function — nothing qualifies Not "no evidence exists" — the trials that exist are placebo-free, in the wrong populations, using unnamed strains, with unreported effect sizes.
- Probiotics, male fertility and semen parameters Grade C for Fertility and semen — one positive trial with a material design defect The only male-specific outcome in the corpus with repeated positive human data — and it is still Grade C, and still not sold in this market.
- Probiotics for IBS in men: the trial record, strain by strain Grade C for Digestion and IBS — one positive trial with a material design defect No human RCT of any named strain, in men only, with an IBS endpoint. What exists: one null sex comparison, two failed primaries, strain by strain.
- Probiotics with antibiotics: diarrhoea, and the one strong reason Grade B for Antibiotic diarrhoea — one adequately powered strain-level trial The strongest evidence-backed reason a man might take a probiotic — and the strain that earns it is not in any men’s product at a knowable dose.
- Probiotics, colds and immunity in men Grade D for Colds and immunity — class-level pooled evidence only The class-level result is the only thing anyone can buy into, and by construction it points at no product. Cochrane’s conclusion in full, then the caveats.
- Probiotics for weight loss: what the trials actually show Grade C for Weight and metabolic — one positive trial with a material design defect Not one sex-stratified weight result in men is positive. The one prespecified body-weight endpoint met in this literature is for a preparation not on sale.
- Probiotics, mood and stress in men Grade F for Mood and stress — nothing qualifies No men-only trial of the marketed strain pair exists for any mood, stress or anxiety outcome, and no sex-stratified mood analysis has ever been published.
- Probiotic safety, and who should not take them The pooled safety data are genuinely reassuring, and the literature that produced those nulls did not systematically look. Both halves, with the scope.
The method, and the data
- The methodology. How the universe was drawn, how a teardown is done, how every grade and every count was produced, the frozen denominators, and what this site does not know.
- The label audit. Every product taken apart at label level — what the panel prints, what resolves to a real culture-collection accession, and what does not.
- The data. The audit as CSV and JSON, with a licence and a citation line, so the tables above can be checked or argued with off this site.
- Corrections. Dated, permanent, and quoting the original error. Several entries are about pages exactly like this one.
- The verdict, and what to buy. The commercial half: five reasons a man arrives here, and what each one ends in. Two of the five end in nothing.