Tongkat Ali's likely hormonal pathway

Tongkat ali increases testosterone tone, but is not a testosterone agonist. Anabolic steroids are testosterone agonists. They cause a negative feedback reaction of the pituitary and hypothalamus (the two glands secrete a series of hormones that signal Leydig and other testosterone synthesizing cells to stop testosterone production). The result is a definite shrinkage of the male genitals, especially the testes. The medical term for the condition is "testicular atrophy".

Tongkat ali is the opposite of a testosterone agonist. But no, it's not a testosterone antagonist. Tongkat ali stimulates testosterone production by interfering with the testosterone negative feedback loop. Even when tongkat ali raises testosterone levels, the upstream pituitary and hypothalamus do not respond by signaling that testosterone synthesis should be tuned down.

The above is part abstract, part model. Tongkat ali has not been fully researched yet. While there is ample evidence that it raises testosterone, the exact mechanism by which it achieves this hasn't been established.

However, there is educated speculation not only by this author.

Stated Lie-Chwen Lin (National Research Institute of Chinese Medicine, Shih-Pai, Taipei 112, Taiwan, R.O.C.) and Chen-Yuan Peng, Hsing-Shun Wang, Kuo-Wu Lee, and Paulus S. Wang (all of the Department of Physiology, National Yang-Ming University, Shih-Pai, Taipei 112, Taiwan, R.O.C.) wrote in a scientific study into the Chemical Constituents of tongkat ali (Eurycoma longifolia by scientific name):

"A preliminary screening demonstrated that the ethanolic extract of Eurycoma longifolia could increase the human chorionic gonadotropin (hCG)-induced production of testosterone by Leydig cells."

For an abstract of the above-cited article, please see:

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1 Binu Tharakan and Bala V. Manyam, Botanical therapies in sexual dysfunction, Wiley Online Dictionary, Phytotherapy Research, Volume 19, Issue 6, pages 457-63, June 2005

2 Boon Cheok Lee, MD, Hui Meng Tan, MD, Late-onset hypogonadism: the Asian experience, Journal of Men's Health, Volume 5, Issue 4, December 2008, Pages 297-302

3 M. Tambi1, M. K. Imran and R. R. Henkel, Standardised water-soluble extract of Eurycoma longifolia, Tongkat ali, as testosterone booster for managing men with late-onset hypogonadism?, Wiley Online Library, Andrologia, Volume 44, Issue Supplement, pages 226-230, May 2012

4 A. George1 and R. Henkel, Phytoandrogenic properties of Eurycoma longifolia as natural alternative to testosterone replacement therapy, Wiley Online Library, Andrologia, Volume 46, Issue 7, pages 708-721, September 2014

5 Christopher C. K. Ho, Hui Meng Tan, Rise of Herbal and Traditional Medicine in Erectile Dysfunction Management, Springer Link, Urology Report, December 2011, Volume 12, Issue 6, pp 470-478

Tongkat ali clinical trials

Having settled in Southeast Asia primarily for sexual purposes, Sam, who has started this site, has lived in the part of the world for a good number of years. While his ability to generate love affairs has constantly improved the longer he has been here, his physical capabilities in the love arena had decreased noticeably at around midlife (mid-40s).

He is now beyond 50 (and has assigned other people to handle the day-to-day maintenance of his websites), and in much better shape than he was 10 years ago. And while the Southeast Asian region is supplying him with better opportunities now than he ever had, the Southeast Asian herbal tongkat ali has been, so he writes, instrumental in restoring his physical and mental fitness for a life full of sex.

Here further comments from Sam:

I have been working in Southeast Asia as a foreign correspondent for German newspapers and radio stations, and I have written a number of conventional travel guides. But in as much as I have grown financially independent, I have attended to projects that were personally important to me.

Gathering scientific and empirical data on tongkat ali, for example. Thus, I have initiated to sort-of open-label clinical trials on tongkat ali extract (supplied by the Indonesian tongkat ali plantation Sumatra Pasak Bumi, with website We have run a first tongkat ali trial in 2003, and I have helped Sumatra Pasak Bumi to set up a second trial in 2004.

Our 2003 trial was geared towards collecting empirical data on tongkat ali usage. Trial participants received 2 free 15-gram samples of 1:50 tongkat ali extract and were encouraged to keep a diary on their sexual activity (several reports have been integrated in the "Tongkat Ali research" section of this website).

The tongkat ali extract was provided as a powder, very similar to an instant coffee powder (but beating coffee in the degree of bitterness). I did not make specific dosage recommendations, but rather recommend that participants started with a very low initial dosage, and if this didn't have the desired effect, to work themselves up to higher dosages.

I myself started with a dosage of 1 gram of extract some 2 to 3 hours before sexual activities.

Many trial participants reported an improvement of some sexual parameters. The strongest pro-sexual effect was reported by older trial participants, and those who had sexual problems to start with.

Sumatra Pasak Bumi's 2004 open-label clinical trial is designed to measure the effect tongkat ali has on levels of testosterone, especially free testosterone. During our 2003 trial, some participants had before-and-after laboratory tests done on testosterone and free testosterone, and in each case, a substantial increase was seen for free testosterone.

This result fitted nicely with the common theory that tongkat ali partially works by increasing the net synthesis of testosterone, as well as by binding to SHBG, thus increasing the plasma percentage of free testosterone (which was previously bound to SHBG).

So, in Sumatra Pasak Bumi's 2004 trial, the aim is to collect laboratory data on how well tongkat ali raises levels of testosterone and free testosterone.

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1 Catherine Ulbricht, Julie Conquer, Kelly Flanagan, Richard Isaac, Erica Rusie, and Regina C. Windsor, An Evidence-Based Systematic Review of Tongkat Ali (Eurycoma longifolia) by the Natural Standard Research Collaboration, Informa Healthcare, Journal of Dietary Supplements Vol. 10, No. 1 , Pages 54-83 March 2013.

2 H. H. Ang and K. L. Lee, Effect of Eurycoma longifolia Jack on orientation activities in middle-aged male rats, Wiley Online Library Fundamental & Clinical Pharmacology Volume 16, Issue 6, pages 479-483, December 2002.

3 Amal Salem Farag Mahmoud and Mahanem Mat Noor, Comparative study on the effect of Eurycoma longifolia and Smilax myosotiflora on male rats fertility, AIP Conf. Proc. 1571, 227 (2013).