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Open WellbeingWhat the studies actually measured

Hormones, thyroid and fertility

Tongkat Aliand Free testosterone

Only one source here so far, and it measured higher free testosterone.

How sure anyone can be

Very low certainty, level 1 of 4

Any estimate here is very uncertain.

The numbers reported

37 percent change
% change in salivary testosterone status vs placebo

None of these sources gave a likely range — the band the real answer probably sits in — so how precise these numbers are is still an open question here.

One source, newest first

What we read is the published abstract, not the full paper, so a blank below may still be printed in the paper itself. A fixed rule worked this out from the source’s own fields. Nobody checked this rating by hand.

  • Randomised trial, 2013 · 63 participants

    Very low certainty, level 1 of 4

    Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects.

    J Int Soc Sports Nutr. 2013;10(1):28. doi:10.1186/1550-2783-10-28. PMID:23705671.

    Number reported
    37 percent change
    Which way it went
    Higher
    Likely range
    Not in the abstract
    Source’s own words
    % change in salivary testosterone status vs placebo
    Who was studied
    Adult with moderate stress
    Compared with
    placebo
    Amount taken
    Not in the abstract
    For how long
    28 days
    Disagreement between studies
    Not in the abstract
    Kind of record
    Journal article
    How this rating was reachedstarts at High, 3 steps down: risk of bias, indirectness and imprecision
    1. Starts at High
    2. Risk of bias brought it down to Moderatethe abstract reports no risk-of-bias or quality appraisal, so study limitations cannot be ruled outNot in the abstract
    3. Indirectness brought it down to Lowthe outcome measured is a proxy for the target outcomeReported in the abstract
    4. Imprecision brought it down to Very lowthe abstract reports no confidence interval for the estimateNot in the abstract
    5. Ends at Very low3 steps down.
    Inconsistency
    One study, so there was nothing to disagree

    Imprecision stops at the first check that applies; others may apply too.

    AI-reviewed & signed — an AI agent re-read this finding against the saved source and checked that the quote, the numbers, the units and the direction match it. No person read it. The owner authorised the agent to sign the batch with the owner's key, and every build rechecks that signature against these exact bytes.

    Read the abstract on PubMed

What is still missing from these readings

  • One gives no likely range, so how precise that number is is unknown.
  • Amount taken — Not in the abstract.

Something nobody wrote down is never a zero and never a guess.

Still to read for Tongkat Ali

Five of the 13 things on our list for Tongkat Ali have no reading here yet:

  • DHEA-sulfate
  • Grip Strength
  • Serum cortisol (morning)
  • Sperm concentration
  • Total sperm motility

Still to read means nobody here has got to it, not that it was tried and did nothing or that no research exists. A pairing on no list is not a gap: we never set out to read it.

Read next

This is a library, not advice. No recommendation, no dose, no diagnosis, no ranking. We never ask about your symptoms, and nothing here is tailored to you.