Fadogia Agrestis: The Testosterone Study Was Rats. The Same Lab Then Found Liver and Kidney Damage.

There is one study connecting this plant to testosterone.

It was done in male albino rats, it ran for five days, and the authors concluded that the extract “may be used to modify impaired sexual functions in animals” [1].

That qualifier is in the paper. It is the first thing that falls off.

What the 2005 study actually did

Researchers at the University of Ilorin in Nigeria took an aqueous extract — the plant stem steeped in water — and gave it to male rats at three doses: 18, 50 and 100 milligrams per kilogram of bodyweight, once a day. They measured sexual behaviour and serum testosterone on days 1, 3 and 5 [1].

The rats mounted more often, took less time to start, and lasted longer before finishing. Serum testosterone rose across all three doses, in a pattern the authors described as suggestive of dose-dependence — more extract, more testosterone [1].

As a rat study, it is a perfectly reasonable rat study. The problem is everything that happened next.

Four years later, the same three authors ran the toxicity study

Same laboratory. Same plant. Same three doses — 18, 50 and 100 mg/kg — this time for 28 days instead of five [2].

Nothing dramatic happened on the surface. No deaths, no visible distress, no swelling or shrinking of the organs [2]. If you were watching the cages, you would have seen nothing.

The blood said otherwise. Three enzymes — alkaline phosphatase, lactate dehydrogenase and gamma-glutamyl transferase — dropped inside the liver and kidney tissue and rose correspondingly in the serum [2].

That pattern has one ordinary explanation. Those enzymes belong inside cells. Finding less of them in the tissue and more of them in the blood is what it looks like when cells leak.

A fourth marker moved too. Malondialdehyde — a by-product of fats being oxidised, used as a rough gauge of membrane damage — rose in every treated group [2]. The authors’ own reading is disruption of the plasma membranes of the liver and kidney cells.

So: one paper found the testosterone. The next paper, from the same three people, found the leak. Only one of them ever gets quoted.

How much human evidence is there? We counted.

PubMed holds twenty records that mention Fadogia at all. Exactly one of them connects Fadogia agrestis to testosterone, and it is the rat study above.

Searched for clinical trials or randomised controlled trials specifically, the count is zero.

That is worth stating precisely, because “no evidence” gets used loosely. This is not a trial that came out negative. It is not a trial too small to conclude from. There is no trial. Nobody has given this to a human being under conditions that would let anyone report what happened.

Nobody knows what dose you would even take

Look again at how the rats were dosed: milligrams per kilogram of bodyweight. A heavier rat got proportionally more.

Now look at a capsule. It carries a flat number of milligrams, the same for everyone, and that number was not derived from a human study, because there is not one.

There is a standard way of scaling animal doses to human ones. We are not going to run it for you, because the output would be an assumption printed next to real measured figures, and on this page that would be the same mistake we are describing. What can be said without inventing anything: the dose on the label is not a finding.

And a fifth of the products had no detectable marker compounds

In 2019 a lab at the University of Mississippi built a method for measuring eleven chemical constituents of Fadogia agrestis, then pointed it at 17 dietary supplements that claimed to contain the plant [3].

Twelve of the seventeen contained detectable phenolic compounds — marker chemicals used to confirm the plant is actually in there — at 0.3 to 2.7 milligrams per day. In five of them, the phenolic compounds were not detected at all [3].

Be careful with what that does and does not prove. Not detecting those markers is not the same as proving the bottle is empty; a different extraction could in principle carry different compounds. But it does mean that for roughly one product in three, the analysis could not confirm the plant was present at a measurable level.

Which puts you in an unusual position. The active claim rests on a rat study, the dose rests on nothing, and the contents of about a third of the bottles could not be confirmed by the people who went looking.

The case report we are not going to use against it

There is a published case of a 27-year-old man who developed acute liver injury after six months on a testosterone-booster supplement [4].

That report does not name Fadogia agrestis, and we are not going to imply that it does. It is here for what its authors actually wrote about, which is more useful anyway.

The man arrived jaundiced and told the hospital he had taken paracetamol for a cold. He was treated for paracetamol poisoning. He improved, went home, and came back two weeks later worse. Only on repeat questioning did the supplement come up at all [4].

The paper is titled “Underreporting Supplements” for that reason. And it explains something about this whole category that is easy to misread: the absence of case reports attached to a specific ingredient is not evidence that the ingredient is safe. It can also mean nobody wrote the ingredient down.

So why is this rated Preliminary rather than Unsupported?

Because those two words mean different things here, and the difference matters.

Unsupported on this site means we looked and the claim failed against the evidence. That is not what happened. Failing requires something to fail against.

Preliminary means early, small, conflicting, or animal-only. This is animal-only, in the most literal sense available: one species, one laboratory, five days, and no human has ever been studied.

Preliminary is not a green light. It is the rating for “nobody can tell yet”, and the definition carries a second half worth reading — not actionable alone. On this page it means the rat data is real, it is genuinely all there is, and the same rats it came from also had enzymes in the wrong compartment.

What we would actually do

Notice what you are being sold. The testosterone number comes from rats. The safety reassurance comes from nowhere — there is no human safety data either, and a category cannot be called well-tolerated on the strength of not having been tested.

If you want the thing that does work, it is dull. We have checked what actually raises testosterone naturally, and the honest answer is sleep, lifting and correcting a deficiency — none of which is a purchase.

And the category has form. Our verdict on testosterone boosters as a class found that not one branded product has ever been tested as sold. Fadogia is not an exception to that pattern. It is an unusually clean example of it.

If you are worried about your testosterone, measure it. That is a blood test somebody qualified orders, and we have written about whether you should.

This is journalism about research, not medical advice. If you are taking this and something feels wrong — particularly anything involving your skin or eyes turning yellow — that is a doctor, today, and tell them about the supplement. How we read a study · The other supplement whose evidence is mostly rodents