Benefits
Testosterone support trials
No LJ100 trial is cited here. The only cited study that measured testosterone was a 6-month trial in men diagnosed with androgen deficiency of the aging male, and both the supplement group and the placebo group also did supervised exercise training, so the training cannot be separated from the supplement. It used a generic tongkat ali extract at 200 mg a day, not LJ100. Nothing cited here shows a testosterone change in healthy men.
No cortisol or stress evidence is cited
No cortisol, mood or stress trial appears in this page's references. The four cited studies looked at sexual well-being, semen quality, and testosterone in aging men. None of them enrolled stressed adults or measured cortisol, so there is nothing here to support a stress benefit.
No strength or exercise-capacity evidence is cited
No muscle strength or exercise capacity trial is cited on this page. The one cited study that involved exercise had every participant training, in both the supplement and the placebo group, and it measured erectile function and testosterone rather than strength or performance.
Standardized eurypeptide content
LJ100 is standardized so that eurypeptide content is consistent from batch to batch. That is a manufacturing consistency claim, and a useful one if you want a predictable product. It does not by itself show that the extract produces any particular effect in people, and no trial of LJ100 itself is cited here.
What the cited studies actually tested
The studies listed on this page do not test LJ100. Two tested Physta, a competing branded extract from another company, and one of those tested Physta combined with Polygonum minus, so its results cannot be credited to tongkat ali alone. A third used a proprietary unbranded extract with no placebo group, and the fourth used a generic extract alongside exercise training.
How it differs from unbranded tongkat ali
Unbranded tongkat ali extracts vary a lot in eurycomanone and eurypeptide content, so a standardized extract gives you a more predictable product from bottle to bottle. That is an argument about consistency and label accuracy. It is not evidence that the branded version works better, because no study cited here compares LJ100 against an unbranded extract, or tests LJ100 at all.
Mechanism of action
Testosterone production support
The proposed explanation for tongkat ali is that it acts on Leydig cells in the testes, which make testosterone, and possibly on sex hormone binding globulin, the protein that holds testosterone in an inactive form. Both are proposed mechanisms. None of the studies cited on this page tested how the extract works, and none tested LJ100 specifically.
Cortisol modulation and stress response
Eurypeptides have been proposed to influence cortisol and the body's stress response, but no study cited on this page measured cortisol or any stress outcome. Treat this as an untested idea rather than an established action.
Standardized bioavailability
Standardization is intended to keep the amount of active compounds the same in every batch. No blood-level or absorption data for LJ100, and no comparison against an unbranded extract, is cited on this page.
Clinical trials
Leitao and colleagues, Maturitas 2021, PMID 33541567. Six-month randomized, double-blind, placebo-controlled trial of 200 mg a day of a generic Eurycoma longifolia extract plus concurrent training in aging men with diagnosed androgen deficiency.
Clinical population described in trial publication.
Nothing on this page tests LJ100 for testosterone. The only cited study that measured testosterone (Leitao and colleagues, Maturitas 2021, PMID 33541567) was an independent 6-month randomized, double-blind, placebo-controlled trial in men diagnosed with androgen deficiency of the aging male. Both groups, supplement and placebo, also did concurrent exercise training, so the exercise cannot be separated from the supplement, and the extract was a generic tongkat ali at 200 mg a day rather than LJ100. Erectile function and total testosterone improved in that setting.
Ismail and colleagues 2012, PMID 23243445: 109 men aged 30 to 55, 300 mg a day of Physta freeze-dried water extract for 12 weeks. Udani and colleagues 2014, PMID 24550993: 26 completers aged 40 to 65, 200 mg Physta combined with Polygonum minus for 12 weeks.
Clinical population described in trial publication.
Both trials reported better erectile function and sexual well-being scores than placebo, and the 2012 study also reported better semen measures. Two limits matter: Physta is a competing branded extract from a different company, not LJ100, and the 2014 study tested it combined with a second herb, so its result cannot be credited to tongkat ali alone. Both had industry involvement, and the 2014 study had only 26 men complete it.
Tambi and Imran, Asian Journal of Andrology 2010, PMID 20348942: 75 men with unexplained (idiopathic) infertility took 200 mg a day of a proprietary water-soluble Eurycoma longifolia root extract.
older adults
Sperm concentration, movement and shape improved over the study. There was no placebo group and everyone knew what they were taking, so the change cannot be separated from normal variation or expectation. This was done in men being treated for a diagnosed fertility problem, not in healthy men, and fertility problems need medical care rather than a supplement.