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Open WellbeingWhat the studies actually measured

Vitamin and mineral levels

Ironand Ferritin

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

How sure anyone can be

Moderate certainty, level 3 of 4

Further research may change this.

The numbers reported

One source’s range, drawn against its own line of no difference and scaled to its own numbers.

0.441.27 standardised effect size2.1

This range stays on one side of the no-difference line.

Bar the confidence interval — the range the true effect is likely to sit inNotch the number the source reportedLine where there would be no difference at all

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.

  • Systematic review, 2024

    Moderate certainty, level 3 of 4

    Effects of Oral Iron Supplementation on Blood Iron Status in Athletes: A Systematic Review, Meta-Analysis and Meta-Regression of Randomized Controlled Trials.

    Sports Med. 2024;54(5):1231-1247. doi:10.1007/s40279-024-01992-8. PMID:38407751.

    Number reported
    1.27 standardised effect size
    Which way it went
    Higher
    Likely range
    0.44 to 2.1
    Source’s own words
    standardised mean difference in serum ferritin vs control
    Who was studied
    Athlete
    Compared with
    control (no oral iron supplementation)
    Amount taken
    16 to 100 mg/d elemental iron
    For how long
    42 to 56 days
    Disagreement between studies
    Not in the abstract
    Kind of record
    Journal article
    How this rating was reachedstarts at High, one step down: imprecision
    1. Starts at High
    2. Imprecision brought it down to Moderatethe abstract does not state how many participants were pooledNot in the abstract
    3. Ends at ModerateOne step down.
    Checked, nothing to step it down for
    risk of bias and indirectness
    Inconsistency
    No disagreement reported, and no count of studies behind it

    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 do not say how many people took part.

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

Still to read for Iron

Nine of the 18 things on our list for Iron have no reading here yet:

  • Bloating Symptom Severity Score
  • Endurance Performance (Time to Exhaustion)
  • Fractional iron absorption
  • Heart rate variability (RMSSD)
  • Hematocrit
  • Serum iron
  • Six-Minute Walk Test Distance
  • Soluble Transferrin Receptor (sTfR)
  • Total Iron Binding Capacity

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

  • Iron

    Eight other questions read for it

  • Vitamin and mineral levels

    15 questions read under it

  • Ferritin

    No other ingredients read against it

    Alphabetical, and by nothing else.

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.