- Any one study can be affected by chance or design.
- Results apply most to the people and product studied.
- Replication by independent groups builds confidence.
- Most shilajit benefits rest on one or two small trials.
Why one study isn’t enough
| Factor | Effect |
|---|---|
| Chance | Small studies can produce results by luck |
| Participants | Results may apply only to similar people |
| Preparation | Results may apply only to that product |
| Design | Weak controls or blinding can bias results |
| Funding | Can shape question, design or reporting |
| Publication | Positive results are more likely to be published |
The role of chance
In a small trial, a few participants responding unusually can shift the average. Statistical tests estimate how likely a result is to be due to chance, but a “significant” result in one small study can still fail to repeat. That is a normal feature of research, not a flaw in any particular study; see statistical significance and sample size.
What replication adds
When different researchers, with different participants and ideally different funders, find similar results, chance and design quirks become much less likely explanations. Replication is the step that turns an interesting result into reliable evidence. In our rating system, independent replication is one of the main factors that can move a topic up the scale; see evidence rating system.
Shilajit examples
Shilajit’s testosterone evidence comes mainly from one 90-day trial in healthy men aged 45 to 55.[1] Its exercise evidence comes mainly from one trial in active men,[2] and its bone evidence from one trial in postmenopausal women.[3] Each is useful, but none has been widely replicated by independent groups with different preparations, which is why each topic is rated “Limited”; see evidence ratings.
Reviews and meta-analyses
Systematic reviews and meta-analyses combine several studies, which can give a clearer picture than any single trial. For tongkat ali, for example, a 2022 meta-analysis pooled five randomised trials on testosterone.[4] Shilajit doesn’t yet have enough similar human trials for that kind of pooled analysis on most topics.
How UK rules reflect this
Health claims on foods and supplements in the UK must be authorised, which requires a substantial body of evidence rather than a single study.[5] Shilajit has no authorised health claims, so products can’t legally claim, for example, that it boosts testosterone; see UK claims rules and testosterone claims.
How single studies get used in marketing
- “Clinically proven”Often based on one trial.
- “Studies show”Sometimes one study, sometimes animal studies.
- Borrowed evidenceA trial of one extract used to sell another product.
Single studies still matter
None of this makes single studies worthless. A well-designed trial is real evidence and a reason to investigate further. The point is proportion: one trial supports a cautious statement, not a confident claim.
Putting it into practice
When you see a benefit claim, ask how many human studies support it and whether they were independent. One study means “early evidence”; several consistent studies from different groups mean much more. Check our evidence ratings for each topic.
A comparison that shows replication at work
Tongkat ali offers a useful contrast. Several randomised trials on testosterone have been pooled in a meta-analysis, giving a larger evidence base than shilajit has on the same question.[4] Even there, the effect appeared mainly in men with low testosterone, and much of the research was funded by one extract maker.[6] Replication improves confidence; it doesn’t remove every question.
What would strengthen shilajit evidence
Larger trials, run by independent groups, using clearly described preparations and outcomes that matter to people, would do most to strengthen the evidence. Until then, each shilajit benefit remains a question worth investigating rather than a settled fact; see evidence gaps.
In short
One study opens a question; replication starts to answer it. Most shilajit benefits are still at the first stage, which is why careful language and realistic expectations matter. When a product calls a single trial “proof”, treat that as a sign of marketing rather than evidence.
What this means when you buy
When a product page leans on “a study shows”, check our rating for that topic before deciding. A Limited rating means there is some human evidence, but you should expect uncertainty about whether, and how much, shilajit will help. Treat it as a reason to try cautiously, with realistic expectations, rather than as a promise of results.
The bottom line
A single study, however interesting, can be affected by chance, its participants, preparation, design or funding. Replication builds confidence. Most shilajit benefits rest on one or two small trials, so treat them as early evidence, not proof.
Frequently asked questions
Can one study prove a health claim?
No. Confidence needs replication by several well-designed studies.
Why does replication matter?
It makes chance and design quirks less likely explanations.
How many studies support shilajit and testosterone?
Mainly one 90-day trial in healthy men aged 45 to 55.[1]
What is a meta-analysis?
A study that statistically combines results from several trials.
Are there authorised health claims for shilajit in the UK?
No. Health claims must be authorised, which requires substantial evidence.[5]
What does “clinically proven” usually mean?
Often one trial, sometimes of a different product.
Are single studies worthless?
No. They are early evidence and a reason to investigate further.
How do your ratings use replication?
Independent replication is a main factor in moving a topic up the scale.
Sources & further reading
Primary research, regulators and standards bodies are cited first. A source being listed here does not mean it supports every claim made by sellers; it supports the specific statement it is attached to.
- Pandit S, Biswas S, Jana U, De RK, Mukhopadhyay SC, Biswas TK. Clinical evaluation of purified Shilajit on testosterone levels in healthy volunteers. Andrologia 48(5):570–575, 2016. PMID 26395129. View source (opens in a new tab) [Randomised controlled trial]
- Keller JL, Housh TJ, Hill EC, Smith CM, Schmidt RJ, Johnson GO. The effects of Shilajit supplementation on fatigue-induced decreases in muscular strength and serum hydroxyproline levels. Journal of the International Society of Sports Nutrition 16:3, 2019. doi:10.1186/s12970-019-0270-2; PMID 30728074. View source (opens in a new tab) [Randomised controlled trial]
- Pingali U, Nutalapati C. Shilajit extract reduces oxidative stress, inflammation, and bone loss to dose-dependently preserve bone mineral density in postmenopausal women with osteopenia: a randomized, double-blind, placebo-controlled trial. Phytomedicine 105:154334, 2022. doi:10.1016/j.phymed.2022.154334; PMID 35933897. View source (opens in a new tab) [Randomised controlled trial]
- Leisegang K, Finelli R, Sikka SC, Panner Selvam MK. Eurycoma longifolia (Jack) improves serum total testosterone in men: a systematic review and meta-analysis of clinical trials. Medicina 58(8):1047, 2022. doi:10.3390/medicina58081047. View source (opens in a new tab) [Systematic review and meta-analysis]
- Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. GOV.UK. View source (opens in a new tab) [Official register]
- Examine. Does tongkat ali increase testosterone levels?. examine.com. View source (opens in a new tab) [Evidence summary (secondary)]