In the realm of Thai herbal tradition, few remedies stand as tall—both literally and culturally—as “pla lai puek” (ปลาไหลเผือก), a revered root with centuries of healing lore and, increasingly, mounting scientific interest. Known across the country by a patchwork of regional names—krung badan in Surat Thani, khanang in Trat, and tung sor in the North—this unassuming root from the Eurycoma longifolia Jack shrub, also called tongkat ali throughout Southeast Asia, is at the crossroads of folk wisdom and modern research, offering health-conscious readers a window into how ancient plant knowledge can inspire today’s medical science.
Thailand’s relationship with pla lai puek is deeply woven into the nation’s communities and cultural identity. Used for generations by healers and traditional practitioners, the root’s place in Thai medicine is both practical and symbolic. Much like its regional neighbors who also revere Eurycoma longifolia, Thais have relied on it for vitality, restoration, and a host of ailments—its name whispered in stories of recovery, renewal, and resilience. But is there truth behind the tales, and does modern science validate the beliefs that persist in rural villages and bustling cities alike?
Originating in the rainforests of Indochina—Cambodia, Laos, Thailand, Vietnam—and stretching to Malaysia and Indonesia, Eurycoma longifolia is a proud member of the Simaroubaceae family, often growing unbranched to heights of up to 10 meters. The root is where its traditional power is said to reside. In Thai traditional medicine, healers harvest, slice, and dry the roots before decocting them in teas or infusions, aiming to address fatigue, fever, sexual debility, and as a restorative tonic—practices well-documented in local pharmacopoeias (medthai.com; ittm.dtam.moph.go.th). Functioning as a “yang tonic” in Southeast Asian belief systems, it is credited with restoring energy, virility, and body heat, making it a popular choice among older men and postpartum women seeking strength.
The cultural footprint of pla lai puek goes further, finding space in ritual practices and family legacies. Passed down within families, it reflects the shared narratives of regional Thais—such as the story of the krung badan, who reportedly regained vitality through root decoctions after bouts of fever. Ethnobotanical surveys consistently rank it as one of the most trusted “roots of power” in both Central and Southern Thailand, and it often features in amulets and talismans meant to ward off fatigue and weakness—symbols of cultural resilience.
Traditional uses, though diverse, frequently point toward its supposed role as an aphrodisiac, antipyretic (fever reducer), anti-malarial, and general tonic for the body (ScienceDirect; disthai.com). Healers and folk practitioners historically prescribed root decoctions for “male weakness,” persistent fevers believed to be malarial, back pain, digestive upsets, and even postnatal recovery for women—reflecting beliefs in its ability to “replenish yang” and fortify life energy.
But what does science say about pla lai puek? Does modern research back up these time-honored uses, or do legends outpace laboratory evidence?
Recent decades have seen a surge in studies investigating the chemical makeup and biological action of Eurycoma longifolia, both in Thailand and abroad. The driving interest often centers on the root’s most famous purported qualities: boosting testosterone, enhancing vitality, and combatting stress. Clinical studies, reviews, and lab-based experiments have all sought to break down the mysteries contained within this powerful root.
Scientific reviews confirm that Eurycoma longifolia contains a range of phytochemicals, the most notable being quassinoids—particularly eurycomanone, which has drawn attention for its diverse biological actions (ACS Omega). Other compounds include alkaloids, saponins, and various antioxidants, giving the root a pharmacological profile that supports its traditional status as a tonic and adaptogen.
Human clinical research is still emerging but increasingly promising, particularly with regard to male reproductive health. A 2022 meta-analysis and systematic review—among the most comprehensive to date—concluded that Eurycoma longifolia supplementation significantly improved serum testosterone levels in men with low baseline testosterone (PMC; PubMed). These findings support the claims of traditional healers who have used the extract to address male sexual debility and age-related fatigue.
Complementary clinical studies validate these effects, with placebo-controlled trials showing tangible improvements in male sexual performance and sperm quality. Healthy middle-aged men supplemented with the root reportedly experienced reduced fatigue, improved mood, and a statistically significant increase in testosterone levels. These findings have reverberated into the global wellness and supplement industries, where “tongkat ali” is now marketed worldwide as a booster of male vigor and athletic performance—though the strength of claims varies and some studies found only modest benefits (Medical News Today; MDPI).
Interestingly, the root’s pharmacological properties are not limited to male reproductive health. Thai and international research indicate broad-spectrum effects: laboratory studies confirm anti-malarial activity, correlating with its historical use against intermittent fever (ScienceDirect). Methanol and water extracts of Eurycoma longifolia root showed efficacy against the malaria parasite Plasmodium, paralleling the root’s reputation among forest dwellers and rubber tappers, who historically used it as a “jungle cure” for lingering fever.
Beyond this, publications also document the plant’s antioxidant, anti-inflammatory, and antimicrobial capabilities (Kochcha Sarn Journal of Science, 2020). These suggest potential for wider therapeutic roles, including wound healing, immune modulation, and even anticancer properties. Recent laboratory research notes that eurycomanone can inhibit the growth and spread of osteosarcoma cells, though findings remain preliminary and are not yet translated into validated treatments for cancer (PubMed).
Thai-specific studies further contextualize the plant. Investigations using cold-storage sperm samples from native Thai chickens have shown that supplementation with Eurycoma longifolia extract improves sperm survival and fertility (PubMed). While this data applies to agricultural science, it echoes the plant’s long-held reputation for boosting male reproductive potential, a belief at the heart of its popularity in local herbal markets and among rural households.
Despite a growing body of research, many health claims remain under debate. Some Western regulatory bodies caution that large, long-term, blinded human studies are lacking, especially regarding mechanisms, optimal dosing, and side effects (Wikipedia). Furthermore, while the traditional risk of toxicity is believed to be low, rare adverse effects have been recorded, including liver injury—primarily in individuals consuming large or highly concentrated supplements, a caution particularly relevant as the plant becomes commodified and exported on a global scale.
Navigating this intersection of tradition and science, it becomes clear that while Eurycoma longifolia (pla lai puek) is richly deserving of its legendary status, responsible use requires balancing legacy with evidence. Traditional Thai wisdom reflects a nuanced approach—roots are typically used as part of complex decoctions, administered under the watchful eye of local healers who modulate dosages and watch for side effects. Modern supplement culture, in contrast, often favors convenience and concentration—capsules, extracts, and powders that may not always respect the balance found in traditional formulations.
For Thai readers seeking to embrace this “root of power,” several practical recommendations emerge:
- Always seek professional consultation before using Eurycoma longifolia or any potent herbal remedy, especially if you have chronic health conditions or are taking prescription medications. Self-medication can lead to unexpected interactions and side effects (Medical News Today).
- Be vigilant about product sources. As demand for “tongkat ali” grows globally, adulteration and contamination risks rise, with some commercial products failing purity or dosage standards. Choose products from reputable, licensed suppliers who provide clear labeling and third-party testing reports (BMJ Open).
- Respect the traditional approach—use moderate doses and prefer whole-root preparations over highly concentrated extracts unless under expert supervision. Traditional Thai healers often employ complex herbal mixtures to balance effects.
- Note that Eurycoma longifolia is no panacea. While it may support vitality and reproductive health for some, it should be viewed as part of a larger holistic lifestyle that includes balanced nutrition, regular exercise, and stress management.
- If adverse reactions (digestive upset, jaundice, allergic symptoms) occur, stop use immediately and consult a healthcare professional.
Pla lai puek’s journey from the heart of Thai forests into the laboratories and clinics of the 21st century speaks to the enduring power of ethnomedicine—nature’s remedies bridging the wisdom of our ancestors and the rigor of modern science. By respecting both heritage and evidence, Thai society can continue to celebrate this botanical treasure while safeguarding community health. As with all traditional medicines, the story is ongoing—each cup of root tea, each new clinical trial, another verse in the evolving epic of Thailand’s natural pharmacy.
Disclaimer: This article is intended for educational purposes only. Consult a qualified healthcare provider before using any herbal remedy to treat health conditions.
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