This supplement may be useful for the following purposes or conditions. Also given is the recommended dosage based on available human research and the current scientific support for use (on a scale of 0-10). Note that a low rating does not necessarily indicate that a supplement does not work, just that research is either unavailable or has not demonstrated a benefit.
- Aphrodisiac - 6
- Anxiety - 5
- Malaria - 5
- Cancer - 4
- Fever - 4
- Parasitic infection - 4
- Testosterone increase - 4
- Ulcers - 4
- Male infertility - 3
- Analgesic - 2
- Hypertension – 2
Side effects
- This supplement has been traditionally used in many countries without reports of serious side effects. However, it has not been studied much in humans, so it is advisable to use this supplement with caution. Using more than a gram a day is not advisable, and it should not be used continuously for more than a month before taking an equivalent amount of time off.
- Eurycoma has androgenic effects when administered to rodents. Androgenic side effects such as prostate enlargement may be a possibility.
- Many users report insomnia from taking this supplement.
Background
Eurycoma longifolia Jack, also known as Tongkat Ali in Malaysia, is a shrub-tree that grows in Malaysia, Burma, Indochina, Thailand, Sumatra, Borneo, and the Phillipines [1]. It is traditionally used primarily as an aphrodisiac and for improving general health [2]. Other traditional uses include treatment of aches, persistent fever, malaria, dysentery, glandular swelling, bleeding (as a coagulant), edema, hypertension, syphilitic sores, and ulcers [3-4]. A large variety of constituents have been identified, including quassinoids, canthin-6-one alkaloids, beta-carbolines, tirucallane-type triterpenes, squalene derivatives, and biphenylneolignans [2].
Uses
Tongkat Ali is primarily used as a male aphrodisiac. In Malaysia, it used to increase virility and sexual prowess and is claimed to improve strength and power during sexual activities [2, 5]. Many animal studies, both in rats and mice, have found administration of E. longifolia extracts to increase sexual arousal and motivation and frequency of sexual activity [2, 5-6]. These effects are similar to those caused by administration of testosterone, although the effect of Tongkat Ali is not as strong [5]. There are no human studies published in peer-reviewed journals yet, although there are many anecdotal reports that would indicate that the aphrodisiac qualities are retained in humans.
A related property that Tongkat Ali is reputed to have is a testosterone-increasing effect [2]. Tongkat Ali does have androgenic effects in male rats, either directly or indirectly, such as increasing the weight of sexual accessories [5, 7]. In vitro, ethanolic extracts of E. longifolia increase hCG-induced production of testosterone by rat leydig cells [3]. There are many anecdotal reports on the internet where people indicate that they had testosterone levels tested before and during Tongkat Ali supplementation, and it caused an increase. The present evidence indicates that this is a likely property of this plant, but how great the effect is, dose-dependency, and whether or not it contributes significantly to the aphrodisiac qualities of Tongkat Ali can only be established with more research. Until then, Tongkat Ali should not be treated as a reliable way to increase testosterone levels.
Many other possible benefits have been identified in experimental studies. An animal study found that Tongkat Ali had anxiety-reducing effects in the open field, elevated plus-maze, and antifighting tests [8]. It also has antimalarial activity in vitro, an effect which is due to multiple constituents of the plant, and which multiple studies have replicated [3]. In an animal study, Tongkat Ali had the ability to improve survival in infected animals, but the effective dose was near-toxic. It was commented that the history of human use as an antimalarial agent may be explained by differences between rodents and humans which causes the toxic effect to be reduced in the second group, but studies are needed to confirm this [9]. Tongkat Ali also has an anticancer effect against multiple cancer cell lines and is effective against multiple parasites in vitro [2, 10].
Dose & Toxicity
There has not been much study done on the safety of Tongkat Ali in humans. One animal study found that the LD50 (dose that kills 50% of test animals) was 1500-2000 mg/kg of the alcohol extract and 3000 mg/kg of the water extract. A subacute toxicity study with the alcohol extract indicated that 600 mg/kg daily was associated with signs of toxicity while 200 mg/kg daily was not, and another study found no toxic effects at 270-350 mg/kg daily but toxic effects were observed at 430 mg/kg daily. The subacute signs of toxicity were increased weight of liver, kidneys, spleen, and testes [9]. Most consider one gram daily to be the maximum dose for supplemental use, although it depends on the potency of the product. For someone weighing about 180 lbs., this dose would equate to 12 mg/kg, less than 5% of a dose that did not cause apparent signs of toxicity in animals, so there is a good margin of safety. However, because there is little data on humans, this supplement should still be used with caution and preferably not for extended periods without taking periodic breaks from use. Also, Tonkgat Ali should not be taken by methods other than oral administration, as this increases toxicity by approximately 100-fold, indicating that the digestive tract filters out many toxic compounds [9].
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