Table 2.
Summary of clinical studies on probiotic-related interventions in women with PCOS.
| Study (Ref.) |
Design and participants | Intervention type | Intervention, dose, and co-intervention | Control | Duration | Primary/major endpoints | Main findings |
|---|---|---|---|---|---|---|---|
| Zhang et al., 2019 (81) |
Two-phase study; probiotic intervention phase included 14 women with PCOS. BMI/PCOS phenotype not reported for the intervention subgroup; no parallel randomized control. | Single-strain probiotic | Bifidobacterium animalis subsp. lactis V9 (reported as B. lactis V9), (4 × 1010 CFU/day), once daily. | None in the 10-week probiotic intervention phase. | 10 weeks | Exploratory monitoring of gut microbiota, strain colonization, SCFAs, gut-brain mediators, LH, LH/FSH ratio, and sex hormones. | Among 9 participants with effective colonization, LH and the LH/FSH ratio decreased, while SCFA concentrations and several sex-hormone-related measures increased. Findings were from a small uncontrolled intervention subgroup. |
| Karamali et al., 2018 (82) |
Randomized, double-blind, placebo-controlled trial; 60 women with PCOS, aged 18–40 years (30/group). BMI/phenotype not clearly specified in the report. | Multi-strain probiotic | Lactobacillus acidophilus, Lacticaseibacillus casei, and Bifidobacterium bifidum; reported concentration 2 × 109 CFU/g for each strain. | Matching placebo. | 12 weeks | Hormonal profiles and clinical hyperandrogenism; inflammatory and oxidative-stress biomarkers. | Compared with placebo, total testosterone, modified Ferriman–Gallwey score, hs-CRP, and MDA decreased; SHBG and TAC increased. HOMA-IR and other metabolic measures showed no significant between-group improvement. |
| Darvishi et al., 2021 (83) |
Randomized, double-blind, placebo-controlled trial; 68 overweight or obese women with PCOS, aged 20–44 years (34/group). | Synbiotic | One 500-mg capsule/day containing Lacticaseibacillus casei, Lacticaseibacillus rhamnosus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus acidophilus, Bifidobacterium longum, Bifidobacterium breve, Streptococcus thermophilus, plus inulin-type fructooligosaccharides. | Starch placebo capsule. | 8 weeks | Glycemic indices, lipid profile, serum apelin, body weight, BMI, and central-adiposity measures. | Fasting glucose, insulin, HOMA-IR, body weight, BMI, waist and hip circumferences, and waist-to-height ratio decreased; HDL cholesterol increased. Total cholesterol, triglycerides, LDL cholesterol, apelin, and waist-to-hip ratio showed no significant between-group change. |
| Ghanei et al., 2018 (89) |
Randomized, double-blind, placebo-controlled trial; 90 women screened, 70 entered the protocol, and 60 completed; Rotterdam-diagnosed PCOS, aged 18–40 years. BMI not clearly reported. | Multi-strain probiotic with drug co-intervention | Lactobacillus acidophilus, Lactiplantibacillus plantarum, Limosilactobacillus fermentum, and Lactobacillus gasseri; reported concentration 1 × 109 CFU/g. Both groups also received cyproterone acetate. | Maltodextrin placebo plus the same cyproterone-acetate regimen. | 12 weeks | Inflammatory markers (IL-6, IL-10, TNF-α, hs-CRP) and anthropometric/clinical measures. | IL-10 increased significantly with probiotics. hs-CRP and IL-6 decreased in both groups, whereas TNF-α showed no significant probiotic-specific change. Interpretation should account for concurrent cyproterone-acetate therapy. |
| Ji et al., 2022 (90) |
Single-center randomized three-arm trial; 60 non-obese women with PCOS, allocated 1:1:1. | Probiotic alone, metformin alone, and combined probiotic + metformin | ProMetS probiotic powder, 4 g/day; metformin, 1.5 g/day; or their combination. Strain composition was not reported in the accessible article abstract/registry. | Active-comparator design: probiotic alone, metformin alone, and combination; no placebo group. | 12 weeks | Primary: improvement in menstrual patterns. Secondary: ovulation, anthropometric measures, metabolic profiles, and hormonal levels. | Menstrual-cycle recovery was 40, 55, and 80%, and ovulation was 30, 55, and 75%, in probiotic, metformin, and combination groups, respectively. The combination was superior for menstrual outcomes; BMI, fasting glucose, HOMA-IR, lipids, AMH, testosterone, and FAI also improved after probiotic and/or metformin treatment. |
| Jamilian et al., 2018 (91) |
Randomized, double-blind, placebo-controlled trial; 60 women with Rotterdam-diagnosed PCOS, aged 18–40 years (30/group). BMI/phenotype not clearly specified. | Multi-strain probiotic + selenium co-supplementation | Lactobacillus acidophilus, Limosilactobacillus reuteri, Limosilactobacillus fermentum, and Bifidobacterium bifidum (2 × 109 CFU/g each; total 8 × 109 CFU/day) plus selenium 200 μg/day. | Matching placebo. | 12 weeks | Primary: hormonal profiles. Secondary: mental-health measures, inflammation, and oxidative-stress biomarkers. | Compared with placebo, BDI, GHQ, and DASS scores improved; total testosterone, hirsutism score, hs-CRP, and MDA decreased; TAC and GSH increased. Because probiotics and selenium were co-administered, their individual contributions cannot be separated. |
| Szydłowska et al., 2025 (92) |
Randomized, double-blind, placebo-controlled trial; 50 women with Rotterdam-diagnosed PCOS (25/group), 43 completed. Mean age 28.4 years; mixed BMI, with potential relevance to overweight/high-FAI phenotypes. | Multi-strain probiotic | SanProbi Barrier: Bifidobacterium bifidum W23, Bifidobacterium animalis subsp. lactis W52 and W51, Lactobacillus acidophilus W37, Levilactobacillus brevis W63, Lacticaseibacillus casei W56, Ligilactobacillus salivarius W24, and Lactococcus lactis W19/W58; 1 × 109 CFU/day. | Matching placebo. | 12 weeks | Hormone concentrations and BMI. | Within the probiotic group, LH, TSH, androstenedione, and BMI decreased, while SHBG increased. Between-group delta changes were significant for TSH, androstenedione, SHBG, and BMI; LH reached significance only with a one-tailed test. Testosterone and DHEAS did not show significant between-group improvement. |
| Chudzicka-Strugała et al., 2025 (93) |
Randomized, placebo-controlled trial; 70 overweight/obese women invited, 65 randomized, and 33 completed 6 months; BMI > 25 kg/m2; Rotterdam PCOS. | Synbiotic + intensive lifestyle modification | SANPROBI Super Formula, four capsules/day: Bifidobacterium animalis subsp. lactis W51/W52, Lactobacillus acidophilus W22, Lacticaseibacillus paracasei W20, Lactiplantibacillus plantarum W21, Ligilactobacillus salivarius W24, Lactococcus lactis W19, plus fructooligosaccharides and inulin. Both groups followed a 1,400–1800 kcal/day diet and daily walking. | Four placebo capsules/day plus the same intensive lifestyle program. | 6 months | Primary: BMI, body composition, and total testosterone. Additional endocrine, metabolic, lipid, and endotoxemia markers. | BMI and body fat decreased similarly in both groups. Synbiotic supplementation produced greater reductions in total testosterone, LH, total cholesterol, LDL cholesterol, triglycerides, LPS, and LBP; fasting insulin decreased and ISI increased in the synbiotic group. |
| Shirani et al., 2025 (94) |
Parallel, double-blind, placebo-controlled randomized trial; 90 women with PCOS, 86 completed. Participants were stratified by BMI < 25 or ≥25 kg/m2. | Two-strain probiotic | Lactobacillus helveticus R0052 and Bifidobacterium longum R0175, total 3 × 109 CFU/day, one capsule before lunch; usual medical care was allowed. | Matching 300-mg maltodextrin placebo plus usual care. | 8 weeks | Hormonal status, oxidative stress, CRP, and clinical symptoms; SHBG was the key variable used for sample-size calculation. | SHBG, TAC, and SOD increased; FAI, CRP, and MDA decreased. Total testosterone was not significantly different between groups after adjustment. Acne, alopecia, and hirsutism did not show significant adjusted between-group improvement. |
HOMA-IR, homeostatic model assessment of insulin resistance; CRP, C-reactive protein; LH, luteinizing hormone; FSH, follicle-stimulating hormone; SHBG, sex hormone-binding globulin; hs-CRP, high-sensitivity C-reactive protein; IL-6, interleukin-6; TNF-α, tumor necrosis factor-α; MDA, malondialdehyde; TAC, total antioxidant capacity; GSH, glutathione; ISI, insulin sensitivity index; LPS, lipopolysaccharide; LBP, lipopolysaccharide-binding protein; DHEAS, dehydroepiandrosterone sulfate; FAI, free androgen index.