Inositol for PCOS

Verdict: Helps PCOS metabolic markers; hard outcomes unproven

Inositol (especially myo-inositol) reliably improves insulin and hormonal markers in women with PCOS, but it has not been shown to deliver the outcomes that matter most, such as live birth, so it is reasonable as an adjunct rather than a proven treatment. The evidence is graded B, preliminary.

B 🟡 B Preliminary Evidence Published with Warning

🔬Why this grade7-layer evidence engine

The grade is B because the benefit is consistent on surrogate markers but weak on hard endpoints. A 2017 meta-analysis (PMID 29042448, 496 women) found myo-inositol significantly lowered fasting insulin (SMD -1.02) and HOMA index (SMD -0.59), with SHBG rising only after 24-plus weeks. A 2025 ART meta-analysis (PMID 40989082) reported a higher clinical pregnancy rate (RR 1.64).

What holds the grade back is the quality of evidence on outcomes patients actually care about. The 2018 Cochrane review (PMID 30570133, 1472 women) was uncertain about live birth (OR 2.42, 95% CI 0.75-7.83) from just 2 trials and 84 women, and the 2024 review informing the 2023 International PCOS Guideline (PMID 38163998, 2230 women) graded every androgenic, metabolic and reproductive outcome as low certainty. Trials also vary widely by isomer and dose.

Regulators and clinics are cautious rather than endorsing. The US FDA treats inositol only as a GRAS nutrient, the UK NHS notes the Inofolic combination helped metabolic markers and cycle regularity in initial studies only, and Mayo Clinic and Harvard do not address it for PCOS. Because most meta-analyses do not disclose funding and industry conflict cannot be excluded, the verdict is published with a warning.

⚖️

Scoring transparency

All scores computed by a 7-layer evidence engine — fully auditable

Raw score 0.65

← counter-evidence / ineffectiveeffective / strong evidence →

Final grade

B · Published with Warning

Confidence

81%

Highly consistent evidence

Evidence level

Cochrane high-quality SR/MA

How strongly each layer supports this effect

lower = less supportive

L1 ExamineGlobal benchmark

0.50

L11 AI re-checkIndependent read

0.65

L5 Clinical bodiesAuthoritative stance

0.67

L2 PubMedPrimary literature

0.70

L3 MechanismPlausibility

0.75

Against Mixed Supports

▸View the full decision path (audit trail)

compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.646
tier_from_score — 依分數區間映射至 tier letter
apply_hec_rules — 高品質 SR/MA 顯示 positive (4 篇 > 0 negative)
tier_strict_requirement_check — Tier 條件達標，未降階
detect_disputes — 偵測到 0 個 hard + 1 個 soft dispute
decide_status — 依 tier + dispute 結果決定 status

📄PubMed studies (4)L2 · primary research & systematic reviews

Inositol for Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis to Inform the 2023 Update of the International Evidence-based PCOS Guidelines

PMID: 38163998 2024 統合分析 n = 2,230

Finding: Across 30 RCTs (19 in meta-analyses), D-chiro-inositol showed low-certainty benefits for SHBG, DHEAS, AUC glucose and AUC insulin versus placebo, with a potential ovulation benefit (OR 11.5, low quality); myo-inositol effects on HOMA-IR were inconclusive and reproductive outcomes likely showed no difference versus metformin. All outcomes were graded low certainty due to small samples, risk of bias and imprecision.

Effect size: DCI ovulation OR 11.5 (low certainty); MI HOMA-IR inconclusive

View on PubMed

Inositol for subfertile women with polycystic ovary syndrome (Cochrane Database of Systematic Reviews)

PMID: 30570133 2018 Cochrane SR n = 1,472

Finding: Across 13 RCTs the authors were uncertain whether myo-inositol improves live birth (OR 2.42, 95% CI 0.75-7.83; very low-quality evidence, only 2 trials / 84 women) or clinical pregnancy rate (OR 1.27, 95% CI 0.87-1.85; very low-quality evidence). A possible miscarriage reduction was unreliable due to heterogeneity. Conclusions were cautious: no high-quality evidence supports current clinical practice.

🟢 High quality Government Effect size: Live birth OR 2.42 (95% CI 0.75-7.83), very low quality; clinical pregnancy OR 1.27 (95% CI 0.87-1.85)

View on PubMed

Myo-inositol effects in women with PCOS: a meta-analysis of randomized controlled trials

PMID: 29042448 2017 統合分析 n = 496

Finding: Myo-inositol significantly decreased fasting insulin (SMD -1.021 uU/mL, 95% CI -1.791 to -0.251, p=0.009) and HOMA index (SMD -0.585, 95% CI -1.145 to -0.025, p=0.041). Serum SHBG rose significantly only when MI was given for at least 24 weeks (SMD 0.425 nmol/L, 95% CI 0.050-0.801, p=0.026). Testosterone showed a non-significant downward trend.

Effect size: Fasting insulin SMD -1.02; HOMA SMD -0.59; SHBG SMD +0.43 (>=24 wk only)

View on PubMed

The effect of myo-inositol on assisted reproductive technology outcomes in women with polycystic ovarian syndrome: A systematic review and meta-analysis of randomized clinical trial studies

PMID: 40989082 2025 統合分析

Finding: Myo-inositol increased clinical pregnancy rate by 64% (RR 1.64, 95% CI 1.25-2.15) and top-grade embryos by 12% (RR 1.12, 95% CI 1.02-1.23), with a slightly higher metaphase II oocyte count (WMD +0.28) but essentially no change in total oocytes retrieved. A reduction in antral follicle count and anti-Mullerian hormone was noted with supplementation.

Effect size: Clinical pregnancy RR 1.64; top-grade embryos RR 1.12

View on PubMed

🏛️Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …

L4a US FDA

Neutral

Inositol is recognized as Generally Recognized As Safe (GRAS) for use as a nutrient supplement; affirmed under 21 CFR 184.1370. source↗

L4b EU EFSA

Neutral

L4c UK NHS

Neutral

A commercially available supplement called Inofolic, which is a combination of Myo Inositol and folic acid, has shown benefit in initial studies to improve the metabolic defect in PCOS and make menstrual cycles more regular. source↗

L4d TW TFDA / 衛福部

Neutral

嬰兒配方食品及較大嬰兒配方輔助食品之檢驗值應符合中華民國國家標準（CNS）所定之標準。 source↗

L4e WHO

Neutral

Minimum 4 mg/100 kcal of myo-inositol; Guidance Upper Level (GUL) 40 mg/100 kcal. [Codex Standard for Infant Formula and Formulas for Special Medical Purposes Intended for Infants, CODEX STAN 72-1981] source↗

L5a NIH Office of Dietary Supplements

Cautious

L5c Cleveland Clinic

Supportive

L5e Specialty Society (condition-mapped)

Neutral

✓PMID 100% verifiedevery citation checked via NCBI Entrez

🔬4 PubMed studiesindependently re-checked by multiple sub-agents

engine_version: v1.0 claim_id: CLM-COND-pcos-INT-inositol-001 繁體中文版 →