Tongkat Ali for Male Infertility
Tongkat ali (Eurycoma longifolia) shows promising but weak, preliminary evidence for male infertility: small early trials report improvements in sperm parameters, but no adequately controlled study has demonstrated higher pregnancy or live-birth rates, and real safety concerns exist. It should not be relied on as a fertility treatment.
Why this grade7-layer evidence engine
This intervention earns a Weak (Grade C) rating because the human evidence is small, heterogeneous, and silent on the outcomes that matter most. The largest fertility trial (PMID 20348942, n=350) was open-label with no placebo arm and only 75 men completing a cycle, so its reported gains in all semen parameters and 14.7% spontaneous-pregnancy figure cannot be attributed to the extract. The one true double-blind RCT (PMID 23243445, n=109) was powered for quality-of-life endpoints and reported +44.4% sperm motility and +18.2% semen volume only as secondary within-group changes, with no pregnancy outcomes.
Higher-tier syntheses do not close the gap. A narrative systematic review (PMID 28259255) found most included studies favorable but pooled no effect sizes, and the only meta-analysis (PMID 36013514) pools serum testosterone (SMD 1.352, 95% CI 0.565-2.138), not fertility or semen quality. An in-vitro study (PMID 22332826) found the extract neutral on sperm at therapeutic concentrations. No clinic or guideline body (Mayo, Cleveland, Harvard, NIH ODS, AUA/ASRM) endorses it by name for infertility.
Safety and regulatory signals also weigh on the grade. The US FDA/OPSS notes products contaminated with heavy metals such as lead and mercury and that human safety is not fully established; the EU EFSA refused a novel-food application, concluding the root extract has potential to induce DNA damage. The bottom line: tongkat ali may modestly affect semen markers, but it is unproven for achieving pregnancy and carries contamination and genotoxicity concerns.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸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 = 0.472
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (1 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status