Tongkat Ali Coffee: The Complete 2026 Guide
CafeBank EditorialTL;DR — The Quick Answer
Tongkat ali (Eurycoma longifolia, also called longjack or Malaysian ginseng) is a Southeast Asian root with 400 years of traditional use as a vitality tonic. The modern clinical record — anchored by a 2022 meta-analysis and a decade of human trials — examines its role in supporting healthy testosterone, cortisol balance, and stress response, with the strongest evidence in men over 40 with age-related hormonal decline.
Key takeaways
- The active compounds are quassinoids, especially eurycomanone — extraction method directly determines how much of these reach the cup.
- Evidence is solid for stress-hormone support and SHBG modulation in men over 40; mixed for athletic performance in young healthy adults; premature for bone, cancer, or fertility-disease endpoints.
- Clinical dose is 200–400 mg/day of standardized extract for 4–12 weeks, taken in the morning.
- Tongkat ali pairs well with the morning coffee window because its mechanism complements caffeine without stacking on the cortisol curve.
- Safety: well-tolerated short-term in healthy adults at clinical doses. Check with a provider if you have hormone-sensitive conditions, take blood thinners, or are pregnant or nursing.
For readers who want tongkat ali in a daily-coffee format, the CafeBank choice is our Exclusive Blend VIP Coffee (3-in-1, 20g) — the only CafeBank SKU containing tongkat ali, alongside maca and guarana. Every herb in our stick is processed with Supercritical CO2 extraction (SFE), an extraction approach that uses pressurised CO2 instead of ethanol or hexane in our process, and that helps retain heat-sensitive quassinoids. Read more about why our extraction method matters for adaptogen quality.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Where the 2012–2022 clinical record actually stands, by endpoint category.
Tongkat ali is sold online with claims that overstep what the clinical evidence actually supports. Some of that framing crosses into regulatory trouble territory. The actual clinical record — a decade of human trials from 2012 through 2022, anchored by a 2022 meta-analysis and two rigorous RCTs — tells a more useful story.
Tongkat ali is a Southeast Asian root with 400 years of traditional use and a modern research base examining its role in supporting healthy testosterone and cortisol balance, particularly in men with age-related decline. Evidence is strongest for stress-hormone support and men over 40; weaker and mixed for athletic performance; premature for bone or cancer claims. This guide walks through what the trials show, where the evidence is solid, where it is thin, and why the extraction method behind a product decides whether the active compounds reach your cup at all. At CafeBank, every herb in our stick — tongkat ali included — is processed with Supercritical CO2 extraction (SFE), the same extraction approach used for high-purity botanical extracts. Within the broader adaptogen landscape, tongkat ali sits alongside ashwagandha, ginseng, and rhodiola — readers comparing those alternatives can compare vs rhodiola in our dedicated breakdown.
One thing up front: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Tongkat ali is a dietary supplement herb, not a drug.
What Is Tongkat Ali?
A 400-year-old Southeast Asian tonic
Tongkat ali (Eurycoma longifolia) is a slender understory tree native to the rainforests of Malaysia, Indonesia, Thailand, and southern Vietnam. The roots — the active part — have been boiled into bitter decoctions and used as tonics for general vitality and stamina, particularly for men, for roughly four centuries (Rehman et al., 2016, PMID 26978330). Traditional use is context, not evidence on its own, but the modern clinical record has caught up to several of the traditional indications.
"Malaysian ginseng" and the active root
In English-speaking markets tongkat ali is often sold as "Malaysian ginseng" — marketing shorthand rather than botanical fact; it is not related to Panax ginseng and behaves differently pharmacologically. Almost all clinically studied material comes from the root, which concentrates the plant's signature active compounds — a class of bitter molecules called quassinoids, of which eurycomanone is the most-studied (George and Henkel, 2014, PMID 24386995). The leaves and stems carry a different, less clinically relevant profile. On a quality label, look for root extract with eurycomanone standardization; anything else is not the material the research examined.
How Tongkat Ali Works: The Eurycomanone Story
Quassinoids and aromatase
Tongkat ali's bitterness is the sensory fingerprint of the quassinoid family, the compound class that carries its pharmacological activity. Eurycomanone is the marker compound used across the clinical literature and industry standardization, accompanied by related quassinoids and bioactive peptides (Rehman et al., 2016, PMID 26978330; George and Henkel, 2014, PMID 24386995). The most-cited action of eurycomanone is its influence on aromatase — the enzyme that converts testosterone into estradiol. Preclinical Leydig-cell work has shown that eurycomanone supports testicular testosterone production by inhibiting aromatase activity, keeping the body's own testosterone available rather than converted (Low et al., 2013, PMID 23810842). This is in-vitro mechanism, not clinical outcome — but it is the molecular story that lines up with the hormone changes observed in the human trials.
SHBG and the "testosterone maintainer" framing
A second mechanism in the phytoandrogen literature is tongkat ali's interaction with sex-hormone-binding globulin (SHBG), which binds circulating testosterone and takes it out of bioavailable play. Tongkat ali extracts have been associated with reduced SHBG activity, keeping existing testosterone in its free, bioavailable form (George and Henkel, 2014, PMID 24386995). Combined with its role in the stress-hormone axis (Talbott et al., 2013, PMID 23705671), the honest framing is that tongkat ali behaves less like a synthetic booster and more like a maintainer of the body's own testosterone, modulating the cortisol/testosterone ratio that age and stress tend to degrade.
Two complementary mechanisms — cortisol attenuation and SHBG modulation — that the human trials track.
The Clinical Evidence (2012–2022)
Unlike many herbal categories, tongkat ali has a genuine RCT base spanning a full decade. Below is what the trials found, in DSHEA-safe language.
Stress and cortisol balance
In a four-week RCT of 63 moderately stressed adults, tongkat ali at 200 mg/day of a standardized water-soluble extract was associated with reduced salivary cortisol and increased salivary testosterone versus placebo, supporting healthy stress-hormone balance (Talbott et al., 2013, PMID 23705671). The real numbers: salivary testosterone was 37% higher and cortisol exposure 16% lower in the supplement group. Some competitor sites have inflated this figure into percentages that do not appear in the original paper and misrepresent the trial. We cite the real numbers because overclaiming is both unethical and regulatory exposure. Talbott also reported no adverse changes to AST or ALT liver markers at 200 mg/day over four weeks — a point we return to in Safety.
Age-related testosterone support
For men with age-related testosterone decline, the evidence is stronger than most readers realize. In men with late-onset hypogonadism symptoms, one month of standardized water-soluble tongkat ali at 200 mg/day was associated with increased serum testosterone and reduced Aging Males' Symptoms scores versus baseline (Tambi et al., 2012, PMID 21671978). In a six-month four-arm RCT of 45 men with age-related androgen deficiency, 200 mg/day combined with concurrent training three times weekly produced the strongest improvements in erectile function scores and total testosterone versus placebo — noting that the ED improvement was confounded with the exercise arm (Leitão et al., 2020, PMID 33541567). A third study in 105 aging men (50–70) with low baseline testosterone reported that Physta® at 200 mg/day was associated with increased total testosterone, reduced fatigue, and improved quality-of-life scores within two to 12 weeks (Chinnappan et al., 2021, PMID 34262417). The three trials converge: in men with low baseline testosterone, tongkat ali was associated with meaningful support for levels already within or approaching the normal range.
The 2022 meta-analysis
The strongest evidence synthesis currently available is the 2022 systematic review and meta-analysis by Leisegang and colleagues, which pooled nine studies including five RCTs and reported a statistically significant increase in total testosterone in men supplementing with Eurycoma longifolia versus control (Leisegang et al., 2022, PMID 36013514). This is the single most important reference for anyone asking whether the category's hormonal signal is real. It is — in the specific populations and at the specific doses examined.
Male reproductive support
In a trial that enrolled 350 men with idiopathic infertility, of whom 75 completed three months of daily 200 mg supplementation, tongkat ali was associated with improvements in semen parameters; 14.7% of the completer cohort had partners who reported spontaneous pregnancy during the study (Tambi and Imran, 2010, PMID 20348942). The paper was observational, not placebo-controlled — supportive rather than definitive. In-vitro work on phenolic-rich extracts has shown that Eurycoma longifolia inhibits enzymes relevant to erectile function (PDE-5, arginase, ACE) alongside antioxidant activity; a head-to-head comparison in the same study found Cylicodiscus gabunensis stronger on all three enzyme endpoints, underscoring this as in-vitro mechanism only, not clinical efficacy (Oboh et al., 2018, PMID 29777610). The honest summary is that the traditional reproductive indications have a plausible mechanistic basis and early clinical signal, not a closed case.
Young healthy men and active seniors
A short RCT in 32 healthy young men reported dose-related increases in total and free testosterone after two weeks at 600 mg/day (Chan et al., 2021, PMID 33559971) — small and short, so we treat it as supporting rather than foundational. A pilot in 25 physically active seniors aged 57–72 reported increases in total and free testosterone plus gains in muscular force after five weeks at 400 mg/day (Henkel et al., 2013, PMID 23754792) — small and unblinded, but extends the picture beyond the classical low-T population. For context, a 2021 systematic review of male testosterone and erectile-function supplements identified Eurycoma longifolia among the most commonly examined ingredients in the category (Kuchakulla et al., 2021, PMID 32358510).
Where evidence is thin — honest limits
The tongkat ali literature has real gaps. Bone health and anti-cancer claims are preclinical — animal and cell-model signals only, no human RCT endpoints, which is why those claims are absent here. Athletic performance is mixed: the Henkel 2013 senior pilot was positive, but more recent trials in younger athletes have returned null results. No published human study has exceeded six months of continuous daily use, so we cannot make multi-year safety claims beyond what short-to-medium-term data supports. And no peer-reviewed trial has examined tongkat ali specifically in a coffee-delivery format — the clinical evidence applies to the herb at clinical doses, in whatever format each trial used.
Why Extraction Method Matters — The SFE Difference
Most tongkat ali shoppers never look past the eurycomanone percentage on the label. But that number only matters if the molecule behind it arrived intact. Eurycomanone and the wider quassinoid family are heat-sensitive, moderately polar molecules. Harsh solvents can leave trace residues; excessive heat can degrade the very compounds you're paying a premium for. Extraction method is the hidden quality lever that decides whether the active molecules in your cup are chemically what the research describes.
The three common extraction approaches
Commercial tongkat ali is produced with three main methods. Hot-water extraction — the traditional and still-dominant approach in the clinical-trial material — is inexpensive and clean, but high temperatures can degrade heat-sensitive quassinoids, and the process concentrates water-soluble peptides at the expense of the full bioactive profile. Ethanol or hexane extraction pulls a wider compound range but leaves solvent residues that must be removed post-extraction; trace residues remain a known concern in lower-grade supplements. Supercritical CO2 extraction (SFE) — the extraction approach CafeBank uses — addresses both concerns directly. Pressurised CO2 at supercritical state behaves simultaneously like a gas and a liquid, pulling bioactives out of the root without the residual-solvent concerns of hexane, acetone, or proprietary industrial blends; when extraction is complete the CO2 returns to a gas and leaves nothing to evaporate off or wash away. Temperature is precisely controlled throughout, helping preserve the heat-sensitive quassinoids that give tongkat ali its activity. This is the same extraction standard used for high-grade botanical pharmaceuticals (Farag et al., 2022, PMID 36687023), applied to every herb in our stick — tongkat ali, maca, and guarana.
Honest framing on the clinical record
Most published human trials of tongkat ali used hot-water extracts standardized to specific marker compounds. That body of research supports the herb itself. What SFE adds is a cleaner, low-residue, temperature-controlled preparation that retains those same marker compounds without the residue or thermal compromise of lower-grade methods. It is not a different herb — it is a more carefully handled one. We do not claim "SFE tongkat ali is clinically proven" — that study has not been published, and we will not misstate the record. A quality label should specify root extract (not leaf or stem), standardization to eurycomanone or total quassinoids, the extraction method, and a measurable dose in the clinical range. A label that can't tell you how the material was extracted is telling you something by omission.
Why Coffee Is a Great Delivery Format
Cortisol rhythm, caffeine synergy
The body's cortisol rhythm peaks in the first hour after waking — the cortisol awakening response — and declines across the morning. An herb supporting a healthy cortisol-to-testosterone ratio (Talbott et al., 2013, PMID 23705671), delivered in the drink most people already reach for, works with existing behaviour rather than against it. Coffee's caffeine and tongkat ali's quassinoid profile act on different systems: caffeine supports acute alertness via adenosine-receptor blockade, while tongkat ali's hormonal and adaptogenic actions play out over weeks of consistent use. The two mechanisms are independent, so a combined delivery does not require either one to "do more work" than it already does.
Dose predictability and product scope
A stick pack delivers a fixed dose every time; loose powders and tinctures don't. For an herb whose clinical studies cluster tightly around 200 mg/day of a standardized extract, dose predictability is the difference between mirroring the research and approximating it. Our flagship 3-in-1 20g stick combines tongkat ali with maca and guarana plus our coffee base. Scope note: tongkat ali is only in the 3-in-1 20g SKU — the 3-in-1 10g and Tabs contain maca and guarana only. If tongkat ali is specifically why you're here, the 20g stick is the product.
If the coffee-format argument lands for you, our Exclusive Blend VIP Coffee (3-in-1, 20g) is the only CafeBank stick that pairs tongkat ali with the morning ritual you already have. The dosing, timing, and safety guidance below applies whether you use our blend or another standardized extract.
Dosing and How to Use It
Clinical dose range and timing
The published literature clusters tightly around 200 mg/day of a standardized tongkat ali root extract, with the senior pilot and a minority of other studies using 400 mg/day (and the Chan 2021 young-men trial using 600 mg/day). Two hundred mg/day is the anchor dose — the level at which the stress-hormone balance (Talbott, PMID 23705671), age-related testosterone support (Tambi 2012 PMID 21671978; Chinnappan 2021 PMID 34262417; Leitão 2020 PMID 33541567), and reproductive-support work (Tambi 2010 PMID 20348942) were done. Morning is the natural fit: it aligns with the cortisol rhythm and slots into the coffee habit. Pre-workout is the second-most-common pattern, with the daily dose taken 30–60 minutes before training (Leitão 2020 was structured this way, with concurrent training three times weekly).
Expectations and cycling
Several trials reported measurable changes within two to four weeks (Chinnappan 2021, Talbott 2013), but the multi-month trials (Leitão 2020, Tambi 2010) are the cleanest benchmark. Give it four weeks for an initial signal and two to three months for a fair read. The longest published continuous-use trial ran six months; beyond that, data thins. A reasonable approach — mirroring the traditional-use pattern — is to cycle (five days on and two off, or three months on with a brief break) rather than open-ended daily use, pending longer-term published safety data.
One stick of our Exclusive Blend VIP Coffee (3-in-1, 20g) delivers a standardized tongkat ali dose in the clinically studied range — built so the morning cup is the dose. Read the safety section below before starting if you take prescription medications or have any of the conditions listed.
Safety and Who Should Be Cautious
Tongkat ali has been generally well tolerated in the trials cited throughout this article; the Talbott 2013 RCT specifically confirmed no adverse changes to liver (AST/ALT), kidney, or hematology markers at 200 mg/day over four weeks (PMID 23705671). That is the dataset to anchor on.
Drug and condition interaction matrix
The table below summarizes known and theoretical interactions, alongside conditions where the published evidence does not support use. This is a conservative read of the literature — when in doubt, talk to your provider before starting tongkat ali.
| Condition or medication | Risk level | Mechanism / context | Recommendation |
|---|---|---|---|
| Hormone-sensitive cancers (prostate, breast, ovarian) | AVOID | Tongkat ali influences aromatase activity and the SHBG–testosterone equilibrium; effect on hormone-driven tumor biology is not characterized in humans. | Do not use without oncology team sign-off. |
| Anticoagulants (warfarin, DOACs) and antiplatelets | CAUTION | Limited human interaction data; herb–drug interactions in this category are common enough to warrant clinician oversight. | Discuss with prescriber before use; avoid self-combining. |
| MAOIs and other serotonergic antidepressants | CAUTION | No direct human interaction studies; mechanistically plausible interactions through hepatic enzyme pathways are not ruled out. | Defer to prescriber; do not start without medication review. |
| Pregnancy and breastfeeding | AVOID | No published human safety data in pregnant or lactating populations; hormonal activity is a precautionary concern. | Do not use during pregnancy or while nursing. |
| Pediatric use (under 18) | AVOID | All clinical studies were conducted in adults; effects on developing endocrine systems have not been studied. | Do not use in anyone under 18. |
| Diagnosed liver disease or elevated liver enzymes | HIGH | The LiverTox monograph assigns tongkat ali a likelihood score D for clinically apparent liver injury; standardized 200 mg/day in clinical trials has not shown enzyme changes, but unverified-quality higher-dose use has produced isolated case reports. | Avoid with active liver disease; use only standardized extracts at clinical doses if hepatologist approves. |
Risk-level vocabulary: AVOID = published evidence or precaution argues against use; HIGH = real but conditional risk requires specialist oversight; CAUTION = monitor closely with prescriber input. This table is general education, not individualized medical advice.
LiverTox context
The U.S. National Library of Medicine's LiverTox monograph assigns tongkat ali a "likelihood score D" — a possible but rare cause of clinically apparent liver injury. Reported cases have been largely in young male bodybuilders, a population in which unacknowledged anabolic-steroid use is a documented confounder. That is context, not dismissal: standardized extracts at 200 mg/day in clinical trials have not shown liver-enzyme changes, while higher doses of unverified quality in populations using other compounds have produced isolated reports. Standardized extract at clinical doses is the most evidence-aligned way to use the herb.
Who should check with a provider before use
- Anyone on prescription medications — particularly hormone-related, diabetes, or blood-pressure medications
- Anyone with diagnosed liver conditions or elevated liver enzymes
- Pregnant or breastfeeding individuals — not studied in these populations
- Anyone with hormone-sensitive conditions (including certain cancers)
- Anyone under 18 — all clinical studies were conducted in adults
- Anyone with scheduled surgery — discuss herbal supplements with your surgical team
Interactions with caffeine
No clinically significant interactions between tongkat ali at clinical doses and normal caffeine intake have been reported; the trials were conducted in populations with typical dietary caffeine exposure. Stay within reasonable daily caffeine ranges for your physiology — that guidance does not change because tongkat ali is in the cup.
Reminder: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Tongkat Ali vs. Maca — Different Tools for Different Goals
Both herbs show up on vitality stacks, and "which one should I take" is the wrong framing — they do different work. Tongkat ali's evidence centres on the cortisol/testosterone ratio, late-onset hypogonadism support, and male reproductive parameters (PMIDs 23705671, 21671978, 34262417, 33541567, 36013514); the trial population is predominantly men with age-related decline or elevated stress exposure. Maca's evidence base, covered in our maca story — adaptogenic energy for men and women, is positioned differently: adaptogenic energy, libido-related outcomes in both men and women (including postmenopausal populations), and general vitality. Maca is typically not framed around testosterone modulation.
Combining maca and tongkat ali isn't either/or — each does different work. Layering guarana's sustained-release caffeine on top (see how guarana's slow-release caffeine differs from coffee caffeine) gives you an alertness profile that doesn't crash at 10:30 AM alongside the slower-building hormonal and adaptogenic support of the other two. Three mechanisms, one morning habit, one stick.
The CafeBank Difference
Three things separate what's in your CafeBank stick from what's on most supplement shelves.
SFE across all three herbs. Tongkat ali, maca, and guarana all processed with our Supercritical CO2 extraction standard — no ethanol or hexane in our process, temperature-controlled, retains heat-sensitive actives. No ethanol or hexane residues, no thermal degradation of heat-sensitive quassinoids and polyphenols.
Coffee-ready, dose-predictable format. A stick pack delivers the same dose every time — no powder measuring, no tincture drops, no guesswork. That matters for an herb whose clinical research clusters around a specific standardized daily dose.
Clear product routing — tongkat ali is only in the 3-in-1 20g SKU. Our 3-in-1 10g and Tabs contain maca and guarana only. If you want tongkat ali, shop our 3-in-1 20g — our tongkat ali, maca, and guarana stick. If tongkat ali isn't what you need, the 10g and Tabs are the right choice.
Browse the full Exclusive Blend VIP Coffee product page for the per-stick breakdown, dose specifics, and current pricing. If tongkat ali is not the lever you need, the Active Blend (3-in-1 10g) and Tabs are our maca + guarana SKUs for different goals.
Frequently Asked Questions
How long until I notice effects? Measurable changes were reported within two to four weeks in the trials (Talbott 2013 at four weeks, Chinnappan 2021 within two). Give it four weeks before judging and two to three months for a fair read.
Can women take tongkat ali? Almost all published human evidence is in men. We don't recommend it as a primary herb for women because the research doesn't support that positioning — maca, discussed in our maca pillar, has a stronger evidence base for female vitality. Women curious about tongkat ali specifically should discuss it with a clinician first.
Is it safe with my morning coffee? Yes, within normal total-caffeine limits. Trials were conducted in populations with typical dietary caffeine exposure, and no clinically meaningful interactions between tongkat ali and caffeine have been reported. The FDA guidance — up to 400 mg/day of total caffeine for healthy adults — is the ceiling to track across your whole day.
What's the dose per CafeBank stick? The 3-in-1 20g stick delivers a standardized tongkat ali dose in the clinically studied range alongside maca and guarana. See the product page for the exact per-stick breakdown.
Why not the 3-in-1 10g or Tabs? Because the 3-in-1 10g and Tabs are maca + guarana only — they do not contain tongkat ali. Tongkat ali is only in the 20g SKU. The 10g and Tabs are built for different moments (daily-driver and portable use); the 20g is our full-spectrum stick for customers who specifically want the tongkat ali profile.
Why not a capsule? Capsules work, but they remove one of the most reliable pieces of the habit: the cup you already make every morning. For an herb that rewards consistent daily dosing, we'd rather embed the dose in a behaviour you already have than hope a capsule bottle gets remembered on month three.
Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Tongkat ali is a dietary supplement herb. Consult your healthcare provider before beginning any supplement regimen, particularly if you are taking prescription medications, have a diagnosed medical condition, are pregnant or breastfeeding, or are under 18.
References
All reference metadata below verified verbatim against PubMed via mcp__claude_ai_PubMed__get_article_metadata on 2026-04-21 as part of v2 remediation.
- Talbott SM, Talbott JA, George A, Pugh M. (2013). Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects. J Int Soc Sports Nutr. DOI: 10.1186/1550-2783-10-28. PMID: 23705671.
- Tambi MIBM, Imran MK, Henkel RR. (2011). Standardised water-soluble extract of Eurycoma longifolia, Tongkat ali, as testosterone booster for managing men with late-onset hypogonadism? Andrologia. DOI: 10.1111/j.1439-0272.2011.01168.x. PMID: 21671978.
- Leisegang K, Finelli R, Sikka SC, Panner Selvam MK. (2022). Eurycoma longifolia (Jack) improves serum total testosterone in men: A systematic review and meta-analysis of clinical trials. Medicina (Kaunas). DOI: 10.3390/medicina58081047. PMID: 36013514.
- Leitão AE, Vieira MCS, Pelegrini A, da Silva EL, Guimarães ACA. (2020). A 6-month, double-blind, placebo-controlled, randomized trial to evaluate the effect of Eurycoma longifolia (Tongkat Ali) and concurrent training on erectile function and testosterone levels in androgen deficiency of aging males (ADAM). Maturitas. DOI: 10.1016/j.maturitas.2020.12.002. PMID: 33541567.
- Chinnappan SM, George A, Pandey P, Narke G, Choudhary YK. (2021). Effect of Eurycoma longifolia standardised aqueous root extract–Physta on testosterone levels and quality of life in ageing male subjects: a randomised, double-blind, placebo-controlled multicentre study. Food Nutr Res. DOI: 10.29219/fnr.v65.5647. PMID: 34262417.
- Chan KQ, Stewart C, Chester N, Hamzah SH, Yusof A. (2021). The effect of Eurycoma longifolia on the regulation of reproductive hormones in young males. Andrologia. DOI: 10.1111/and.14001. PMID: 33559971.
- Tambi MIBM, Imran MK. (2010). Eurycoma longifolia Jack in managing idiopathic male infertility. Asian J Androl. DOI: 10.1038/aja.2010.7. PMID: 20348942.
- Henkel RR, Wang R, Bassett SH, Chen T, Liu N, Zhu Y, Tambi MI. (2013). Tongkat Ali as a potential herbal supplement for physically active male and female seniors — a pilot study. Phytother Res. DOI: 10.1002/ptr.5017. PMID: 23754792.
- Low BS, Choi SB, Abdul Wahab H, Das PK, Chan KL. (2013). Eurycomanone, the major quassinoid in Eurycoma longifolia root extract increases spermatogenesis by inhibiting the activity of phosphodiesterase and aromatase in steroidogenesis. J Ethnopharmacol. DOI: 10.1016/j.jep.2013.06.023. PMID: 23810842.
- Oboh G, Adebayo AA, Ademosun AO. (2018). Phenolic-rich extracts of Eurycoma longifolia and Cylicodiscus gabunensis inhibit enzymes responsible for the development of erectile dysfunction and are antioxidants. J Basic Clin Physiol Pharmacol. DOI: 10.1515/jbcpp-2017-0160. PMID: 29777610.
- Rehman SU, Choe K, Yoo HH. (2016). Review on a Traditional Herbal Medicine, Eurycoma longifolia Jack (Tongkat Ali): Its Traditional Uses, Chemistry, Evidence-Based Pharmacology and Toxicology. Molecules. DOI: 10.3390/molecules21030331. PMID: 26978330.
- Kuchakulla M, Narasimman M, Soni Y, Leong JY, Patel P, Ramasamy R. (2020). A systematic review and evidence-based analysis of ingredients in popular male testosterone and erectile dysfunction supplements. Int J Impot Res. DOI: 10.1038/s41443-020-0285-x. PMID: 32358510.
- George A, Henkel R. (2014). Phytoandrogenic properties of Eurycoma longifolia as natural alternative to testosterone replacement therapy. Andrologia. DOI: 10.1111/and.12214. PMID: 24386995.
Supportive references: - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Tongkat Ali monograph. National Institute of Diabetes and Digestive and Kidney Diseases; updated October 2024. ncbi.nlm.nih.gov/books/NBK609015 - Farag MA, Ajayi AO, Taleb M, Wang K, Ayoub IM. (2022). A Multifaceted Review of Eurycoma longifolia Nutraceutical Bioactives: Production, Extraction, and Analysis in Drugs and Biofluids. ACS Omega. DOI: 10.1021/acsomega.2c06340. PMID: 36687023. - NIH Office of Dietary Supplements. ods.od.nih.gov - U.S. FDA — Structure/Function Claims Guidance for Dietary Supplements. fda.gov structure/function claims