Tongkat Ali for Testosterone
Tongkat Ali (Eurycoma longifolia) does appear to raise serum testosterone modestly in men, but the evidence rests on a few small, mostly low-quality and partly industry-funded trials. No major health authority endorses it, while regulators flag possible genotoxicity and heavy-metal contamination, so treat it as a plausible but unproven option rather than an established testosterone booster.
Why this grade7-layer evidence engine
The efficacy signal is real but fragile. A 2022 systematic review and meta-analysis of five randomized trials (PMID 36013514) found a statistically significant rise in serum total testosterone (SMD 1.35, 95% CI 0.57-2.14, p=0.001), with the effect confirmed in hypogonadal men. But the pooled trials were few, small and heterogeneous in dose and extract, the confidence interval is wide and imprecise, and one trial carried a high risk of bias. That keeps the evidence at a preliminary B, not a confident A.
Individual trials point the same way but share the same weaknesses. The strongest controlled data come from an industry-funded Physta RCT in ageing men with low baseline testosterone (PMID 34262417, n=105), showing dose-responsive increases. Smaller trials in young healthy men (PMID 33559971, n=32, 600 mg/day, 2 weeks) and in androgen-deficient older men combined with exercise (PMID 33541567, n=45) were directionally positive, while the often-cited late-onset hypogonadism study (PMID 21671978, n=76) had no placebo control. Benefit looks clearest in older or hypogonadal men and least convincing when testosterone is already normal.
Crucially, no clinical or regulatory body backs it. Major institutions (Mayo Clinic, Cleveland Clinic, Harvard, NIH Office of Dietary Supplements) do not address or endorse Tongkat Ali for testosterone, and the safety picture is adverse. The EFSA issued an unfavourable opinion citing potential genotoxicity and DNA damage, and the US FDA/OPSS warns that products have been contaminated with heavy metals such as lead and mercury, and adulterated with prescription drugs. Weak trial quality, manufacturer conflicts of interest, no endorsement, and real safety signals together justify a cautious, warning-flagged B.
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 = 0.657
- 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