Check · Supplements · Tongkat Ali and Fadogia In review

Do Tongkat ali and Fadogia agrestis naturally raise testosterone and boost male vitality?

Claim attributed to Popularized by Andrew Huberman (Huberman Lab); herbal-testosterone supplement sellers and affiliate marketers. , Huberman described a personal protocol (about 400 mg tongkat ali daily, about 600 mg Fadogia in cycles) while himself flagging rat toxicity and advising bloodwork; the strongest "boosts testosterone" framing comes from sellers, and the Physta ingredient maker has a direct commercial stake.

Verdict Unproven

Evidence grade C Low certainty

Two ingredients, two very different evidence levels, lumped into one promise. Tongkat ali shows small, short-term, mostly maker-funded testosterone effects in stressed or low-T men; Fadogia has zero human trials and a rat testicular-toxicity signal, so the stack as sold is unproven, and the Fadogia half is taken on faith.

It nudges a blood marker in stressed or low-T men over a few weeks; it has never been shown to make a healthy man's life better, and the Fadogia half has no human safety data at all.

The theory

What it’s supposed to target

Testosterone / free testosterone
Luteinizing hormone (Fadogia)
Cortisol-to-testosterone ratio
Libido

These are two different herbs sold as one “natural testosterone” stack. Tongkat ali (Eurycoma longifolia) is proposed to free up bound testosterone and improve the cortisol-to-testosterone ratio in stressed men, plausibly nudging libido and energy. Fadogia agrestis is pitched further up the chain: in rodents it appeared to raise luteinizing hormone, the pituitary signal that tells the testes to make testosterone, so the theory is that it revs the body's own production.

The evidence is lopsided and thin. Tongkat ali has a handful of small human trials with modest, mixed results, enough to be plausible, not enough to be proven. Fadogia is the real problem: its testosterone effect comes essentially only from rat studies, one of which also showed testicular toxicity at higher doses, and there are almost no human safety data. The stack owes its fame largely to a popular podcast rather than to clinical evidence, and the sellers profit directly. Taking an unstudied compound on rodent data is a gamble, not a protocol.

Mechanism is theory, not proof. A plausible pathway explains why something might work, not whether it does. The verdict rests on the evidence below, not the elegance of the theory.

The claim

What would have to be true

Tongkat ali would have to lower SHBG and cortisol enough to raise free testosterone in humans (only partly holds: total T rises, free T does not).

Fadogia would have to act as an LH secretagogue that safely raises testosterone in humans (does not hold: rat-only, with toxicity).

The combined stack would have to outperform either alone in healthy men without harm (does not hold: untested).

The evidence

What the evidence actually shows

Tongkat ali: real but modest, and the money runs one way

The strongest trial is a 12-week RCT in 105 hypogonadal men (testosterone under 300 ng/dL, age 50 to 70) on Physta extract: total testosterone rose significantly vs placebo and Aging Male Symptoms and fatigue scores improved. But free testosterone showed no significant between-group difference, softening the 'more usable testosterone' story, and a 4-week study reported +37% testosterone and -16% cortisol in stressed adults. Both were funded by Biotropics Malaysia, the Physta maker, with company employees as authors. Effects are small, short, and concentrated in stressed or low-T men, not healthy eugonadal men.

Fadogia agrestis: rodent-only, and the testosterone signal arrives with a toxicity signal

Every human-efficacy and human-safety claim for Fadogia rests on rats. Yakubu 2005 found a dose-dependent rise in serum testosterone and mating behavior at 18/50/100 mg/kg. The same group's 2008 study, same doses over 28 days, found adverse changes in testicular function indices that the authors call signs of testicular toxicity, with partial recovery only at the lowest dose. So the one piece of direct evidence that Fadogia raises testosterone comes hand in hand with evidence it can harm the testes, and the popular human dose is backed by no human study.

Evidence quality

Studies, graded, and who paid

Tongkat ali modestly raises total testosterone C Low certainty

Two small RCTs show a rise vs placebo, but both were funded by the extract's maker and effects are modest and short-term.

It raises usable (free) testosterone D Very low certainty

In the strongest trial free testosterone showed no significant between-group difference vs placebo.

Fadogia agrestis raises testosterone in humans D Very low certainty

No human trials exist; the only direct evidence is rat data that also showed testicular damage.

The stack is safe as commonly dosed D Very low certainty

No human safety data for Fadogia; the popular 600 mg dose derives from no human study.

Cited studies with type, size, funding/conflicts, and limitations.
#	Study	Type	Size	Funding / COI	Key limitations
1	Chinnappan/Physta 12-wk RCT, hypogonadal men	RCT (double-blind, placebo-controlled)	n=105, 12 weeks	Industry-funded Funded by Biotropics Malaysia, maker of Physta; two authors were company employees.	Total T rose vs placebo but free T did not; maker-funded; only low-T older men.
2	Talbott tongkat ali stress RCT	RCT (double-blind, placebo-controlled)	n=63, 4 weeks	Industry-funded Funded by Biotropics Malaysia; authors tied to tongkat-ali and nutrition firms.	Short, mixed-sex, maker-funded; stressed adults only.
3	Yakubu Fadogia aphrodisiac (rats)	Preclinical animal (rat)	Male rats, days 1 to 5	Independent Academic (University of Ilorin); no industry sponsor.	Rodent-only, short; no human evidence; rat count unspecified.
4	Yakubu Fadogia testicular toxicity (rats)	Preclinical animal (rat) toxicity	Male rats, 28 days	Independent Academic (University of Ilorin); no industry sponsor.	Single group, small; establishes a signal, not a human risk figure.
5	Read Andrew Huberman (claimant summary)	Promotional/claimant documentation	n/a (anecdote)	, Secondary Substack summary with affiliate links; documents claim, not efficacy.	Some attributed figures are not actually on this page; not evidence.

'Natural' is doing heavy lifting here: it implies safe and effective, yet the only safety data on the Fadogia half is a rat study showing harm.

See who funded the studies behind every Caveat check

Stay neutral

Unproven ≠ disproven

Unproven is not disproven: tongkat ali may help stressed or low-T men, and Fadogia might do something in humans, but no one has run the trial to find out.

The gap

Where claim and evidence diverge

The gap is structural: dietary-supplement rules require no pre-market trials, so the only tongkat studies are short and maker-funded, and Fadogia's rat-toxicity signal deters any first-in-human testosterone trial.

Follow the funding

The money trail

Both tongkat-ali RCTs were funded by Biotropics Malaysia, maker of the Physta extract, with company employees as authors.

Huberman's platform and affiliate/seller pages profit from amplifying the claim; Fadogia has no sponsor funding any human trial.

Bottom line

The honest read

For tongkat ali the honest read is 'small, mixed, conflicted human signal'; for Fadogia it is 'no human evidence plus a rat safety flag.' The paired promise outruns the proof.

Falsifiable

What would change this verdict

An independently funded RCT in healthy men showing the stack raises free testosterone and function vs placebo.

A published human safety study of Fadogia agrestis establishing a tolerable dose and no testicular harm.

Receipts

Sources

Common questions