The short version
- The term adaptogen was established by N. V. Lazarev in 1947 and formalised by Brekhman and Dardymov in a 1969 Annual Review of Pharmacology paper on plant substances that increase non-specific resistance.
- The European Medicines Agency's herbal committee concluded in a 2008 reflection paper that the term adaptogen is not accepted in pharmacological and clinical terminology commonly used in the EU and is not appropriate for a marketing authorisation.
- A 2022 meta-analysis of 12 randomised trials in 1,002 participants found ashwagandha reduced stress (SMD −1.75) and anxiety (SMD −1.55) versus placebo, with heterogeneity above 83% and the certainty of evidence rated low.
- A systematic review of Rhodiola rosea found 11 trials, of which only two of six for physical fatigue and three of five for mental fatigue were positive, and every included study carried a high or unclear risk of bias.
- The main randomised reishi trial used 5.4 grams of polysaccharide extract daily for eight weeks in 132 diagnosed patients, which is a clinical dose in a clinical population rather than a consumer gummy in a healthy adult.
It is printed on the front of thousands of jars, ours included, and almost nobody selling it can tell you where it came from or what it is supposed to mean. So: the term was originally established by N. V. Lazarev in 1947, to describe a substance that increases non-specific resistance to adverse influences and stress. Brekhman and Dardymov formalised it for an English-speaking audience in 1969, in a paper for the Annual Review of Pharmacology whose title is the definition — "New substances of plant origin which increase nonspecific resistance."
Non-specific resistance. That phrase is doing enormous work, and it is where the trouble starts.
The original criteria are stricter than the marketing
Brekhman set out what an adaptogen had to be, and the European Medicines Agency reproduced the list in its own review of the concept. An adaptogen is almost non-toxic to the recipient. It is non-specific in its pharmacological properties, increasing resistance to a broad spectrum of adverse biological, chemical and physical factors. It acts as a regulator with a normalising effect across organ systems. And its effect is more pronounced the deeper the disturbance in the organism.
Read the second one again. Non-specificity is not an incidental feature of the definition — it is the core of it. Which means the word is describing a substance that does a little of everything and nothing in particular, and that is precisely the kind of substance you cannot design a clean trial around. The definition and the demand for evidence are pulling in opposite directions, and they have been since 1947.
What happened when a regulator looked at it
In 2008 the European Medicines Agency's Committee on Herbal Medicinal Products published a reflection paper on the adaptogenic concept, adopted on 8 May of that year. It is short, it is public, and it is the most useful document in this whole field.
The committee acknowledged that numerous pre-clinical and clinical studies have been done to prove the concept. Then it described what it found in them: deficiencies in the description of inclusion and exclusion criteria, in the description of the medication, in diagnosis, in study design and in analysis; a very wide range of clinical conditions investigated; and in some studies very small numbers of patients. Its verdict on eleuthero, the plant the paper was written around, was that none of the studies would be sufficient to substantiate efficacy in a clearly defined clinical condition — although the data taken together justify further research.
And then the sentence: as such, the term is not accepted in pharmacological and clinical terminology commonly used in the EU. The committee judged "adaptogen" not appropriate for a marketing authorisation, while allowing that the concept is worth considering when assessing traditional herbal medicines.
The United States has no regulatory definition of the word either. What governs what we are allowed to say is the general rule that a supplement may describe an effect on structure or function and may not claim to treat, cure or prevent a disease. "Adaptogen" is not a category anyone certified. It is a word.
So which of them actually have human trial data?
This is the question the label cannot answer, and the answers vary enormously between plants that get sold as interchangeable.
Ashwagandha has the most. A 2022 meta-analysis pooled 12 randomised controlled trials covering 1,002 participants and found reductions in anxiety (SMD −1.55) and stress (SMD −1.75) against placebo. Both effect sizes are large, and both come with heterogeneity above 83%, which means the trials disagreed with each other substantially. The authors rated the certainty of the evidence as low for both outcomes. That is still the best-supported plant in the category, which tells you where the bar sits.
Rhodiola is genuinely contradictory. A systematic review found 11 eligible trials; two of six examining physical fatigue in healthy populations reported it effective, as did three of five examining mental fatigue. Every single included study carried either a high risk of bias or reporting flaws that made its true validity impossible to assess. The reviewers' conclusion was that a rigorous, well-reported trial is still needed. That was 2012.
Reishi has one reasonably sized randomised trial, and we want to be careful with it because we sell a reishi product. It enrolled 132 patients with a diagnosed condition, gave them 1,800mg of a polysaccharide extract three times daily — 5.4 grams a day — for eight weeks, and found 51.6% of the treated group rated more than minimally improved against 24.6% on placebo. That is a real result in a clinical population at a clinical dose. It is not a gummy, and it is not a healthy adult having a stressful quarter. We are not going to hand you that trial and let you assume it transfers.
Eleuthero is the plant the EMA paper was written about, and the committee's finding above is the honest summary.
What we'd actually tell you
Ignore the word. It carries no information about dose, species, plant part, extract strength or whether anyone has tested the thing in people. Judge the plant instead, with three questions.
- Which species and which plant part, named on the label?
- What dose, and does it match the dose in the trials rather than a fraction of it?
- Was it tested in people who were not already ill — and if not, say so out loud, because that gap is where most of this category's marketing lives.
Applied honestly to our own shelf: ashwagandha clears all three with caveats, reishi clears the first and fails the third, and the word on the front of the jar clears none of them.
Good questions
What does adaptogen actually mean?
It means a plant substance said to increase non-specific resistance to stress — a definition coined in 1947 and formalised in 1969. Note the word non-specific: the original criteria describe something that acts broadly rather than on one system, which is exactly what makes the claim hard to test.
Is adaptogen a regulated term?
No. Europe's herbal medicines committee reviewed the concept in 2008 and declined to accept the term into clinical or pharmacological terminology, judging it inappropriate for a marketing authorisation. The United States has no definition for it either. Seeing it on a label tells you nothing that has been verified by anyone.
Which adaptogen has the best evidence?
Ashwagandha, by a clear margin, with 12 randomised trials pooled in a 2022 meta-analysis. That said, the same analysis rated the certainty of that evidence low and found the trials disagreeing substantially with one another. Best in this category is not the same as strong in absolute terms.
Do reishi gummies do the same thing as the reishi in the studies?
Almost certainly not, and we sell reishi gummies. The main randomised trial used 5.4 grams of a polysaccharide extract daily for eight weeks in diagnosed patients. A gummy delivers a small fraction of that in a different form to a different person. Enjoy it as a ritual, not as that trial.
How long do adaptogens take to work?
The trials that found anything mostly ran eight to twelve weeks, so that is the window to judge by. If you have taken something daily for three months and cannot point to a specific change you would have noticed anyway, stop. That result is information, and it saves you money.
Can I take more than one adaptogen at the same time?
You can, but you lose the ability to tell which one did anything, and combination products have almost no trial data behind them. Nearly every study in this field tested a single plant at a single dose. If you are experimenting, run one at a time for eight weeks each.
Sources
- Committee on Herbal Medicinal Products (HMPC), European Medicines Agency. Reflection paper on the adaptogenic concept. Doc. Ref. EMEA/HMPC/102655/2007, adopted 8 May 2008. View study
- Brekhman II, Dardymov IV. New substances of plant origin which increase nonspecific resistance. Annu Rev Pharmacol, 1969. View study
- Akhgarjand C, Asoudeh F, Bagheri A, et al. Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials. Phytother Res, 2022. View study
- Ishaque S, Shamseer L, Bukutu C, Vohra S. Rhodiola rosea for physical and mental fatigue: a systematic review. BMC Complement Altern Med, 2012. View study
- Tang W, Gao Y, Chen G, et al. A randomized, double-blind and placebo-controlled study of a Ganoderma lucidum polysaccharide extract in neurasthenia. J Med Food, 2005. View study
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
