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Open WellbeingWhat the studies actually measured

Cholesterol and blood fats

Quercetinand LDL cholesterol

Two sources here, and they say different things: one measured lower LDL cholesterol and one found no clear difference.

How sure anyone can be

Low certainty, level 2 of 4

Further research is likely to change this.

The most certain of the two findings here; each record carries its own.

The numbers reported

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

-1.35-0.88 standardised effect size-0.41

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

Two sources, newest first

We do not pick between these or average them into one number.

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, 2020

    Low certainty, level 2 of 4

    The effects of quercetin supplementation on lipid profiles and inflammatory markers among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized controlled trials.

    Crit Rev Food Sci Nutr. 2020;60(11):1855-1868. doi:10.1080/10408398.2019.1604491. PMID:31017459.

    Number reported
    -0.88 standardised effect size
    Which way it went
    Lower
    Likely range
    -1.35 to -0.41
    Source’s own words
    standardised mean difference vs control
    Who was studied
    Adult with metabolic syndrome
    Compared with
    placebo or control
    Amount taken
    Not in the abstract
    For how long
    Not in the abstract
    Disagreement between studies
    I2: 92.7
    Kind of record
    Journal article
    How this rating was reachedstarts at High, 2 steps down: risk of bias 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. Imprecision brought it down to Lowthe abstract does not state how many participants were pooledNot in the abstract
    4. Ends at Low2 steps down.
    Checked, nothing to step it down for
    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 review could not confirm it — an AI agent re-read this finding against the saved source and at least one check failed. The batch record names the check and quotes the sentence that caused the doubt. No person read it.

    Read the abstract on PubMed

  • Systematic review, 2017

    Low certainty, level 2 of 4

    Effects of quercetin supplementation on lipid profile: A systematic review and meta-analysis of randomized controlled trials.

    Crit Rev Food Sci Nutr. 2017;57(4):666-676. doi:10.1080/10408398.2014.948609. PMID:25897620.

    Number reported
    1.43 mg/dL
    Which way it went
    No clear difference
    Likely range
    -0.92 to 3.78
    Source’s own words
    mg/dL LDL-C, weighted mean difference vs control
    Who was studied
    Not stated in the abstract
    Compared with
    control
    Amount taken
    Not in the abstract
    For how long
    Not in the abstract
    Disagreement between studies
    Not in the abstract
    Kind of record
    Journal article
    How this rating was reachedstarts at High, 2 steps down: risk of bias 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. Imprecision brought it down to Lowthe confidence interval includes no effectReported in the abstract
    4. Ends at Low2 steps down.
    Checked, nothing to step it down for
    indirectness
    Inconsistency
    No disagreement reported, and no count of studies behind it

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

    Source saved; quote checked byte-for-byte against it by software; no signature.

    Read the abstract on PubMed

What is still missing from these readings

  • Two do not say how many people took part.
  • Amount taken — Not in the abstract.
  • For how long — Not in the abstract.

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

Still to read for Quercetin

Seven of the 19 things on our list for Quercetin have no reading here yet:

  • Common cold incidence
  • Endurance Performance (Time to Exhaustion)
  • Fasting insulin
  • HDL cholesterol
  • Interleukin-6
  • Oxidative stress (F2-isoprostanes)
  • Uric acid

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.