Tongkat Ali Trials: What Was Measured, And In Whom

Tongkat ali, Eurycoma longifolia, is a shrub native to Southeast Asia with a long history of traditional use there. On the AlphaSteel panel it is row six: 10 mg, “from 100:1 extract, equivalent to approximately 1000 mg of dry Tongkat Ali powder”.

Two numbers, then. The weight in the two-capsule serving is 10 mg of extract. The dry-powder equivalent, about 1,000 mg, describes how much raw plant that extract was concentrated from. They answer different questions: the first is what you swallow, the second is how concentrated it is.

In the formula as a whole, tongkat ali is row six of seven and 10 of the 118 mg in a serving, a little under a tenth by weight. It is one ingredient among seven, which matters when a single trial of that ingredient is quoted as if it described the product.

A clinical result is a finding about a group of people, measured in a particular way over a particular time. Change the people and the result may not hold. Something that helps men with a hormone deficiency may do nothing measurable in men without one, and a finding in stressed adults over four weeks says little about anyone else over six months.

That is not a technicality. It is the most common way supplement research gets misquoted: a result in one group is repeated as if it were a property of the ingredient in everyone, then as if it were a property of every product that contains it. Reading tongkat ali’s trials by population is the simplest defence against both mistakes.

The six-month trial by Leitão and colleagues, published in Maturitas in 2021, enrolled 45 men aged about 47 on average who had androgen deficiency of aging males. They took a daily Eurycoma longifolia extract, with or without concurrent training, against placebo, and the trial measured erectile function and testosterone levels.

The largest change came in the group that combined the extract with training. Two things about that sentence matter. The men had a diagnosis, so the result describes them, not healthy men. And training was part of the best-performing arm, so the extract was not working alone.

Talbott and colleagues studied a different population entirely: 63 moderately stressed adults, 32 men and 31 women, given a standardised hot-water root extract or placebo for four weeks. The measures were psychological mood-state scores and salivary cortisol.

The extract group reported lower tension, anger and confusion scores, and salivary cortisol exposure fell by 16%. The abstract gives no daily amount, so this study offers a population and a duration, but no figure to compare with a label.

A 2022 meta-analysis by Leisegang and colleagues reviewed nine studies and pooled five randomised trials, in healthy men and in men with hypogonadism. It reported a rise in total testosterone across the pooled trials.

Pooling makes a result look larger and more general than any single trial, and that is exactly when the population question matters most. The pooled groups mixed men with a diagnosis and men without one, so the headline figure blends two different starting points. The abstract lists no doses, which leaves the amount question open as well.

The 2024 systematic review by Morgado and colleagues stepped back further, assessing 27 ingredients sold to raise testosterone across 52 studies. Most failed to raise total testosterone. Eurycoma longifolia was among the few rated possibly effective, for healthy men and for men with late-onset hypogonadism.

‘Possibly effective’ is a careful phrase, and it is worth keeping careful. It describes the ingredient, in the amounts and forms those studies used, in the men they enrolled. It is not a rating of any product, and AlphaSteel’s label makes no hormone claim: its three lines say supports energy and performance, male vitality, and confidence and performance.

Even where a trial states an amount, matching it to a label is harder than it looks, because tongkat ali is sold in several forms. The Talbott study used a standardised hot-water root extract. Other products use plain powdered root, or concentrates described only by a ratio, like the 100:1 on the AlphaSteel panel.

A ratio describes how much raw plant went into the extract. It does not say what the extract was standardised to, or how it compares with the extract a trial used. The NIH background on botanical supplements explains why two products with the same plant on the label can differ widely in what they contain.

So the honest comparison is a loose one. A trial’s amount of one extract and a label’s amount of another cannot be ranked precisely without knowing both preparations, and the label and the trial each give only half of that.