The Research Behind PROUROL

The research behind PROUROL

Evidence-based urinary tract support. Pharmaceutical-grade manufacturing. Reviewed by urologists.

At Sunn Biolabs, every formulation begins with peer-reviewed evidence. PROUROL is our urinary tract and bladder support formula, built around three well-studied ingredients — cranberry proanthocyanidins standardized to 36 mg per serving, D-mannose, and Lactobacillus probiotics — manufactured to pharmaceutical-grade standards and refined with input from practicing urologists. This page summarizes the published research behind PROUROL, with links to the original studies on PubMed.

These statements have not been evaluated by the Food and Drug Administration. PROUROL is a dietary supplement and is not intended to diagnose, treat, cure, or prevent any disease, including urinary tract infections. Consult your healthcare provider before starting any new supplement, especially if you have a history of urinary tract infections or other urologic conditions.

BUILT ON SCIENCE  |  CLINICALLY INFORMED  |  UNCOMPROMISINGLY CLEAN

Cleveland Clinic  ·  UCLA  ·  Cedars-Sinai  ·  Queen's University  ·  Providence  ·  Keck Medicine of USC

Members of our Medical Advisory Board and formulation consultants hold academic and clinical appointments at these institutions.

ON THIS PAGE

  • About urinary tract health and recurrent UTI
  • The research behind PROUROL — ingredient by ingredient
  • What makes PROUROL different
  • Part of a multi-modal approach to urinary tract health
  • Full references

About urinary tract health and recurrent UTI

Why urinary tract infections are so common, and what research tells us about prevention.

A common concern, especially for women

Urinary tract infections (UTIs) are among the most common bacterial infections seen in outpatient medicine. Approximately 50–60% of adult women will experience at least one UTI in their lifetime, and roughly 20–30% of women who experience one UTI will have a recurrence [1]. The dominant pathogen is uropathogenic Escherichia coli, which accounts for approximately 75–95% of uncomplicated UTIs; the remainder are most often caused by Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis, and Staphylococcus saprophyticus [2].

What "recurrent UTI" means clinically

The joint American Urological Association, Canadian Urological Association, and Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (AUA/CUA/SUFU) guideline defines recurrent uncomplicated UTI in women as two culture-confirmed episodes in six months, or three in twelve months [3]. The 2025 AUA/CUA/SUFU guideline amendment [4] updates this framework with stronger recommendations for non-antibiotic prevention options — notably cranberry, vaginal estrogen in perimenopausal and postmenopausal women, and increased water intake.

Treatment vs. prevention: two different questions

Acute UTI treatment is antimicrobial. The joint IDSA/ESCMID guideline recommends nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin as first-line agents for acute uncomplicated cystitis [5]. PROUROL is not a treatment for urinary tract infection. It is a daily dietary supplement formulated to support urinary tract structure and function, and is positioned within the prevention and general-support side of a comprehensive urinary health plan — never as a substitute for professional medical evaluation and antibiotic treatment when indicated.

The postmenopausal picture

In postmenopausal women, estrogen decline is associated with changes to the vaginal and urogenital microbiome — specifically, a loss of vaginal Lactobacillus dominance, a rise in vaginal pH, and increased E. coli colonization. The landmark 1993 Raz and Stamm NEJM trial demonstrated that intravaginal estriol in postmenopausal women with recurrent UTI normalized vaginal pH, restored Lactobacillus dominance, and was associated with a substantial reduction in UTI episodes [6]. This trial established the conceptual link between urogenital Lactobacillus dominance and urinary tract health that frames much of the modern probiotic literature.

The urobiome: the bladder is not sterile

For decades, the healthy bladder was assumed to be sterile. That assumption has been overturned. Using expanded quantitative urine culture (EQUC), Hilt and colleagues demonstrated in 2014 that live bacteria could be cultured from roughly 80% of catheterized urine samples from adult women — while 92% of the same samples had been reported as "no growth" by standard clinical culture. The most prevalent genera in the healthy female bladder were Lactobacillus, Corynebacterium, and Streptococcus [7]. Parallel 16S rRNA sequencing work by Pearce, Wolfe and colleagues has further characterized the female urinary microbiome (urobiome) and shown differences in urobiome composition between women with and without lower urinary tract symptoms [8].

The emerging picture: the healthy female urinary tract has its own resident microbial community, and Lactobacillus species appear to be a signature of a healthy urobiome. This is the conceptual backbone of modern probiotic-informed urinary health formulas, including PROUROL.

The research behind PROUROL

What's in the formula, and what's the evidence?

Cranberry extract standardized to 36 mg proanthocyanidins — the lead ingredient

Cranberry is PROUROL's strongest-evidence ingredient and its most defensible clinical anchor. The research supports a specific dose standard — 36 mg of proanthocyanidins (PACs) per day — which is the PAC dose PROUROL delivers.

The 2023 Cochrane systematic review. The current Cochrane systematic review of cranberries for UTI prevention (Williams et al. 2023, pooling 50 randomized trials and 8,857 participants) concluded that cranberry products were associated with a reduced risk of symptomatic, culture-verified UTIs in (a) women with recurrent UTI, (b) children, and (c) people susceptible to UTI following bladder interventions, with moderate-certainty evidence for the women-with-recurrent-UTI subgroup [9]. This is the most rigorous and most-cited cranberry evidence base available.

The 36 mg PAC dose-response. Howell and colleagues (2010) conducted a multicenter randomized double-blind dose-response study comparing cranberry powders standardized to 0, 18, 36, or 72 mg of PAC. At six hours post-intake, urine from participants taking the 36 mg or 72 mg PAC doses showed significantly greater ex vivo anti-adhesion activity against uropathogenic E. coli than placebo or 18 mg (p = 0.002) [10]. This study is the pharmacodynamic foundation for 36 mg PAC/day as a meaningful anti-adhesion threshold — and it is the specific dose PROUROL is standardized to.

Mechanism. Cranberry's A-type proanthocyanidins — a class of polyphenols that are uniquely abundant in Vaccinium macrocarpon (the North American cranberry) — have been shown in laboratory studies to interfere with the adhesion of P-fimbriated uropathogenic E. coli to urothelial cells, the first step in urinary colonization [11].

Guideline endorsement. The 2025 AUA/CUA/SUFU recurrent UTI guideline amendment explicitly incorporates cranberry as a non-antibiotic prevention option in women with recurrent UTI, reflecting the strengthened evidence base of the 2023 Cochrane review and related trials [4].

Supporting trial data. Additional randomized trials include Vostalova et al. 2015, in which 500 mg/day of cranberry fruit powder in women with recurrent UTI was associated with a lower UTI rate than placebo over six months [12]; Foxman et al. 2015, in which cranberry capsules reduced post-operative UTI rates in women undergoing elective gynecologic surgery [13]; and Kontiokari et al. 2001, an early randomized trial in BMJ showing cranberry-lingonberry juice reduced UTI recurrence in women with a history of E. coli UTI [14].

What the cranberry evidence is — and what it is not. The Cochrane review, the 2025 AUA/CUA/SUFU guideline, and the Howell 2010 dose-response study all address cranberry as a general-population prevention tool studied in women with recurrent UTI. They are not clinical evidence for PROUROL as a finished product, and individual results will vary. PROUROL is not intended to diagnose, treat, or cure any disease. If you have recurrent UTIs, work with a qualified urologist or primary-care clinician on a comprehensive plan.

D-Mannose — an honestly framed evidence base

D-mannose is a naturally occurring simple sugar that has been studied for urinary tract health for roughly two decades. The evidence base is mixed, and PROUROL's framing reflects that honestly.

Mechanism. D-mannose binds the FimH adhesin at the tip of type-1 fimbriae on uropathogenic E. coli. The proposed mechanism is that once bound, the bacteria become less able to adhere to the mannose-containing receptors on urothelial cells, supporting the body's natural clearance of bacteria from the urinary tract [15].

Early positive trial. The foundational trial was Kranjčec et al. 2014, a three-arm open-label randomized trial (n=308) in women with acute cystitis and a history of recurrent UTI. Over six months, UTI recurrence was 14.6% in the D-mannose group vs. 20.4% on nitrofurantoin antibiotic prophylaxis vs. 60.8% with no prophylaxis, with significantly fewer adverse events on D-mannose than on antibiotic [16].

Systematic review signal. Lenger et al. 2020 pooled eight studies (n=719) and concluded that D-mannose appeared protective against recurrent UTI compared with placebo, while noting substantial heterogeneity and calling for larger placebo-controlled trials [17]. De Nunzio et al. 2021 reviewed the mechanistic and clinical landscape and positioned D-mannose as a promising non-antibiotic option pending more rigorous data [18].

The large null trial. In 2022, the Cochrane D-mannose review (Cooper et al.) concluded that there was insufficient evidence to determine whether D-mannose is effective for preventing or treating UTI, with very-low to low-certainty evidence across seven studies [19]. Then in 2024, Hayward and colleagues published the results of the NIHR-funded MERIT trial in JAMA Internal Medicine — a large, well-designed, double-blind, placebo-controlled randomized trial of 2 g daily D-mannose vs. matched placebo over six months in 598 UK women with recurrent UTI. The trial was null: the proportion of women contacting ambulatory care with a clinically suspected UTI was 51.0% on D-mannose vs. 55.7% on placebo (risk difference −5%; 95% CI −13% to +3%; p = 0.26). The authors concluded that daily D-mannose should not be recommended for UTI prophylaxis in this primary-care setting [20].

Why we still include D-mannose, framed honestly. D-mannose has a well-characterized mechanism (FimH anti-adhesion) and an early evidence base that suggested benefit, but the largest and best-designed placebo-controlled trial to date did not demonstrate a reduction in clinically suspected UTI. PROUROL includes D-mannose as a structure-function ingredient that contributes to urinary tract support. We do not claim D-mannose prevents UTI, and we do not rely on older trials in isolation. A clinician can advise whether D-mannose is appropriate for your situation.

Lactobacillus casei probiotic blend (10 billion CFU)

The conceptual basis for including a Lactobacillus probiotic in a urinary health formula rests on the urobiome research summarized earlier: Lactobacillus is a dominant genus in the healthy female urinary and vaginal microbiomes, and loss of Lactobacillus dominance is associated with urogenital dysbiosis and increased E. coli colonization [7][8][6].

Class-level probiotic evidence for urinary tract health. Several randomized trials have studied Lactobacillus probiotics in women with recurrent UTI, generally with different strains than PROUROL's L. casei:

  • Intravaginal L. crispatus. Stapleton et al. 2011 (the Lactin-V phase-2 trial) studied intravaginal Lactobacillus crispatus CTV-05 in 100 premenopausal women with recurrent UTI; UTI recurrence was 15% on Lactin-V vs. 27% on placebo [21].
  • Oral L. rhamnosus GR-1 + L. reuteri RC-14. Beerepoot et al. 2012 randomized 252 postmenopausal women with recurrent UTI to 12 months of oral probiotic capsules or oral TMP-SMX antibiotic; the probiotic was associated with a meaningful absolute reduction in UTI recurrence without increasing antibiotic resistance, though it did not statistically meet the pre-specified noninferiority margin vs. antibiotic [22].
  • Oral probiotic can reach the vaginal microbiome. Reid et al. 2003 demonstrated in 64 healthy women that daily oral L. rhamnosus GR-1 + L. fermentum RC-14 was associated with increased vaginal lactobacilli and decreased vaginal coliforms — establishing that orally administered Lactobacillus can reach the urogenital microbiome [23].

Direct L. casei urinary evidence. The specific published work on Lactobacillus casei in a urinary tract context is preclinical. Asahara et al. 2001 demonstrated that a single intraurethral dose of L. casei Shirota administered 24 hours before E. coli challenge reduced bacterial burden and inflammation in the murine bladder, and that other Lactobacillus species tested (L. fermentum, L. jensenii, L. plantarum, L. reuteri) did not show the same antimicrobial activity in that model [24]. This supports the biological plausibility of L. casei's urinary-relevant activity but is a preclinical, not a clinical, finding.

Combination-formula pilot data. Closer to PROUROL's category concept, two published pilot studies evaluated combination formulas of cranberry + D-mannose + Lactobacillus. Vicariotto 2014 reported an open-label pilot of cranberry extract, D-mannose, and L. plantarum LP01 + L. paracasei LPC09 in 33 women with cystitis, with improvements in symptom scores [25]. Koradia et al. 2019 ran a double-blind placebo-controlled pilot (n=90) of a cranberry + dual-Lactobacillus combination in premenopausal women with recurrent UTI, with a significantly lower rate of UTI recurrence in the combination arm [26]. Both pilots used different Lactobacillus strains than PROUROL; both support the overall category rationale for combining cranberry, D-mannose, and Lactobacillus probiotics.

An honest note on strain-specific claims. Probiotic clinical effects can be strain-specific. The strongest randomized-trial evidence for Lactobacillus in women with recurrent UTI was generated with L. crispatus CTV-05 (intravaginal) and L. rhamnosus GR-1 + L. reuteri RC-14 (oral) — not with L. casei. We cite those studies here because they establish that Lactobacillus species have been evaluated for urinary tract health in well-designed trials; we do not claim that those trial results transfer directly to the L. casei in PROUROL. PROUROL's Lactobacillus casei is included to contribute to the class-level rationale for Lactobacillus-supported urogenital microbial balance. Individual results will vary.

What makes PROUROL different

How PROUROL is formulated, and why.

Cranberry at the 36 mg PAC evidence-backed dose

The Howell et al. 2010 dose-response study established that 36 mg of cranberry proanthocyanidins per day is the threshold at which meaningful ex vivo anti-adhesion activity against uropathogenic E. coli appears in urine [10]. Many over-the-counter cranberry products either do not disclose their PAC content or are standardized to lower levels. PROUROL is standardized to 36 mg of proanthocyanidins per daily serving — matching the dose in the pharmacodynamic literature.

Cranberry, D-mannose, and Lactobacillus in one daily formula

Combination formulas of cranberry + D-mannose + Lactobacillus are an emerging category-standard approach to daily urinary tract support, and the limited controlled-pilot data available on that specific combination has been promising (Vicariotto 2014 [25], Koradia 2019 [26]). PROUROL delivers all three in a single four-capsule daily serving (two capsules twice daily), eliminating the need to stack separate cranberry, D-mannose, and probiotic products.

Pharmaceutical-grade manufacturing

PROUROL is manufactured in a GMP-certified facility to pharmaceutical-grade quality standards. Each batch is assayed for ingredient identity, potency, and contaminants before it leaves the facility. That rigor is especially important for a probiotic product, where CFU viability at end-of-shelf-life, and for a standardized botanical, where PAC content is the whole point of the standardization.

Refined by a Medical Advisory Board

PROUROL's formulation is reviewed and refined by Sunn Biolabs' Medical Advisory Board, a group of practicing urologists with expertise in urinary tract health, recurrent UTI prevention, and women's urologic care. Our MAB reviews ingredient selection, dosing, strain designations where applicable, manufacturing protocols, and the evolving clinical evidence on an ongoing basis.

Part of a multi-modal approach to urinary tract health

Effective urinary tract health support is not a single-product story. Current AUA/CUA/SUFU guidance [3][4] and published clinical reviews point to a layered approach that combines behavioral and hydration strategies (adequate water intake, postcoital voiding), topical vaginal estrogen in perimenopausal and postmenopausal women when clinically appropriate (per Raz and Stamm 1993 and subsequent work [6]), and non-antibiotic supplements including cranberry — now supported in the 2025 guideline amendment [4] — and, where appropriate, probiotics [21][22].

When an acute UTI does occur, antibiotic therapy remains first-line treatment per IDSA guidelines [5]. PROUROL is not a substitute for antibiotic treatment when a UTI is diagnosed. It is a daily supplement positioned within the prevention and general support side of the urinary health picture.

Women with a history of recurrent UTI, men with urinary symptoms, and anyone with persistent or severe urinary complaints should work with a qualified urologist or primary-care clinician to build an individualized plan. PROUROL is designed to contribute to the supplement component of that plan — not to replace medical evaluation, diagnosis, or treatment.

Full references

All citations are peer-reviewed and PubMed-indexed (unless otherwise noted). Click a PubMed ID (PMID) to read the original paper.

  1. Foxman B. Urinary tract infection syndromes: occurrence, recurrence, bacteriology, risk factors, and disease burden. Infect Dis Clin North Am. 2014;28(1):1–13. PMID: 24484571
  2. Flores-Mireles AL, Walker JN, Caparon M, Hultgren SJ. Urinary tract infections: epidemiology, mechanisms of infection and treatment options. Nat Rev Microbiol. 2015;13(5):269–84. PMID: 25853778
  3. Anger J, Lee U, Ackerman AL, et al. Recurrent Uncomplicated Urinary Tract Infections in Women: AUA/CUA/SUFU Guideline. J Urol. 2019;202(2):282–289. PMID: 31042112
  4. Kenneally C, Anger JT, Ackerman AL, et al. Updates to Recurrent Uncomplicated Urinary Tract Infections in Women: AUA/CUA/SUFU Guideline (2025). J Urol. 2025. PMID: 40905426
  5. Gupta K, Hooton TM, Naber KG, et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: a 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis. 2011;52(5):e103–20. PMID: 21292654
  6. Raz R, Stamm WE. A controlled trial of intravaginal estriol in postmenopausal women with recurrent urinary tract infections. N Engl J Med. 1993;329(11):753–6. PMID: 8350884
  7. Hilt EE, McKinley K, Pearce MM, et al. Urine is not sterile: use of enhanced urine culture techniques to detect resident bacterial flora in the adult female bladder. J Clin Microbiol. 2014;52(3):871–6. PMID: 24371246
  8. Pearce MM, Hilt EE, Rosenfeld AB, et al. The female urinary microbiome: a comparison of women with and without urgency urinary incontinence. mBio. 2014;5(4):e01283-14. PMID: 25006228
  9. Williams G, Hahn D, Stephens JH, Craig JC, Hodson EM. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2023;4(4):CD001321. PMID: 37068952
  10. Howell AB, Botto H, Combescure C, et al. Dosage effect on uropathogenic Escherichia coli anti-adhesion activity in urine following consumption of cranberry powder standardized for proanthocyanidin content: a multicentric randomized double blind study. BMC Infect Dis. 2010;10:94. PMID: 20398248
  11. Howell AB. Bioactive compounds in cranberries and their role in prevention of urinary tract infections. Mol Nutr Food Res. 2007;51(6):732–7. PMID: 17487930
  12. Vostalova J, Vidlar A, Simanek V, et al. Are high proanthocyanidins key to cranberry efficacy in the prevention of recurrent urinary tract infection? Phytother Res. 2015;29(10):1559–67. PMID: 26268913
  13. Foxman B, Cronenwett AE, Spino C, Berger MB, Morgan DM. Cranberry juice capsules and urinary tract infection after surgery: results of a randomized trial. Am J Obstet Gynecol. 2015;213(2):194.e1–8. PMID: 25882919
  14. Kontiokari T, Sundqvist K, Nuutinen M, Pokka T, Koskela M, Uhari M. Randomised trial of cranberry-lingonberry juice and Lactobacillus GG drink for the prevention of urinary tract infections in women. BMJ. 2001;322(7302):1571. PMID: 11431298
  15. Bouckaert J, Berglund J, Schembri M, et al. Receptor binding studies disclose a novel class of high-affinity inhibitors of the Escherichia coli FimH adhesin. Mol Microbiol. 2005;55(2):441–55. PMID: 15659162
  16. Kranjčec B, Papeš D, Altarac S. D-mannose powder for prophylaxis of recurrent urinary tract infections in women: a randomized clinical trial. World J Urol. 2014;32(1):79–84. PMID: 23633128
  17. Lenger SM, Bradley MS, Thomas DA, Bertolet MH, Lowder JL, Sutcliffe S. D-mannose vs other agents for recurrent urinary tract infection prevention in adult women: a systematic review and meta-analysis. Am J Obstet Gynecol. 2020;223(2):265.e1–265.e13. PMID: 32497610
  18. De Nunzio C, Bartoletti R, Tubaro A, Simonato A, Ficarra V. Role of D-mannose in the prevention of recurrent uncomplicated cystitis: state of the art and future perspectives. Antibiotics (Basel). 2021;10(4):373. PMID: 33915821
  19. Cooper TE, Teng C, Howell M, Teixeira-Pinto A, Jaure A, Wong G. D-mannose for preventing and treating urinary tract infections. Cochrane Database Syst Rev. 2022;8(8):CD013608. PMID: 36041061
  20. Hayward G, Mort S, Yu LM, et al. D-mannose for prevention of recurrent urinary tract infection among women: a randomized clinical trial. JAMA Intern Med. 2024;184(6):619–628. PMID: 38587819
  21. Stapleton AE, Au-Yeung M, Hooton TM, et al. Randomized, placebo-controlled phase 2 trial of a Lactobacillus crispatus probiotic given intravaginally for prevention of recurrent urinary tract infection. Clin Infect Dis. 2011;52(10):1212–7. PMID: 21498386
  22. Beerepoot MAJ, ter Riet G, Nys S, et al. Lactobacilli vs antibiotics to prevent urinary tract infections: a randomized, double-blind, noninferiority trial in postmenopausal women. Arch Intern Med. 2012;172(9):704–12. PMID: 22782199
  23. Reid G, Charbonneau D, Erb J, et al. Oral use of Lactobacillus rhamnosus GR-1 and L. fermentum RC-14 significantly alters vaginal flora: randomized, placebo-controlled trial in 64 healthy women. FEMS Immunol Med Microbiol. 2003;35(2):131–4. PMID: 12628548
  24. Asahara T, Nomoto K, Watanuki M, Yokokura T. Antimicrobial activity of intraurethrally administered probiotic Lactobacillus casei in a murine model of Escherichia coli urinary tract infection. Antimicrob Agents Chemother. 2001;45(6):1751–60. PMID: 11353622
  25. Vicariotto F. Effectiveness of an association of a cranberry dry extract, D-mannose, and the two microorganisms Lactobacillus plantarum LP01 and Lactobacillus paracasei LPC09 in women affected by cystitis: a pilot study. J Clin Gastroenterol. 2014;48 Suppl 1:S96–S101. PMID: 25291140
  26. Koradia P, Kapadia S, Trivedi Y, Chanchu G, Harper A. Probiotic and cranberry supplementation for preventing recurrent uncomplicated urinary tract infections in premenopausal women: a controlled pilot study. Expert Rev Anti Infect Ther. 2019;17(9):733–740. PMID: 31516055

These statements have not been evaluated by the Food and Drug Administration. PROUROL is a dietary supplement and is not intended to diagnose, treat, cure, or prevent any disease, including urinary tract infections. Individual results may vary. Consult your healthcare provider before starting any new dietary supplement, particularly if you are pregnant or nursing, have a history of urinary tract infections or other urologic conditions, have a compromised immune system, or are taking prescription medications. The peer-reviewed research cited on this page summarizes studies of individual ingredients and of related formulations — including studies that used different probiotic strains than the one in PROUROL — and does not constitute clinical evidence specific to PROUROL as a finished product. If you develop symptoms of a urinary tract infection (burning with urination, urinary frequency or urgency, pelvic pain, fever, or blood in the urine), seek evaluation from a qualified healthcare provider; acute UTI is treated with antibiotics prescribed by a clinician, and dietary supplements are not a substitute for medical treatment.