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Open WellbeingWhat the studies actually measured

Cholesterol and blood fats

Omega-3 fatty acids (EPA/DHA)and Triglycerides

All four sources here measured lower triglycerides.

How sure anyone can be

Moderate certainty, level 3 of 4

Further research may change this.

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

The numbers reported

-15 percent change
% relative reduction in serum triglycerides vs usual/lower intake
-15 percent change
percent reduction in serum triglycerides (2020 Cochrane pool, 86 RCTs, n=162,796)
-5.9
mg/dL reduction in triglycerides per 1 g/day LC omega-3 (58-trial dose-response)

Two further sources recorded only which way the numbers went, without a number.

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.

Four sources, newest first

Five entries follow: one source was read here more than once, and each reading has its own entry.

What we read includes published abstracts and full documents. Each blank below names only what was recorded in that reading. Some of these ratings came from a fixed rule with nobody checking them by hand, and some from a person. Each working below says which.

  • Systematic review, 2023

    Moderate certainty, level 3 of 4

    Not in this document

    Wang T, et al. Association Between Omega-3 Fatty Acid Intake and Dyslipidemia: A Continuous Dose-Response Meta-Analysis of Randomized Controlled Trials. J Am Heart Assoc. 2023 (90 RCTs, 72,598 participants). doi:10.1161/JAHA.123.029512.

    Number reported
    Not in this document
    Which way it went
    Lower
    Likely range
    Not in this document
    Source’s own words
    near-linear triglyceride lowering (direction only; most evident at >2 g/day); 90 RCTs, n=72,598
    Who was studied
    Adult
    Compared with
    placebo or control
    Amount taken
    Recorded detail — g/d
    For how long
    Not in this document
    Disagreement between studies
    Not in this document
    Kind of record
    Systematic review and meta-analysis
    How this rating was reachedstarts at High, one step down: imprecision
    1. Starts at High
    2. Imprecision brought it down to ModerateThe reason for this step is not on record here.
    3. Ends at ModerateOne step down.
    Not written down for this rating
    risk of bias, indirectness and inconsistency

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

    Published before the signing gate; not yet re-verified.

    Read the source document

  • Systematic review, 2020

    Moderate certainty, level 3 of 4

    Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.

    Cochrane Database Syst Rev. 2020;3(3):CD003177. doi:10.1002/14651858.CD003177.pub5. PMID:32114706.

    This source later carried a notice: Update of Cochrane Database Syst Rev. 2018 Nov 30;11:CD003177. doi: 10.1002/14651858.CD003177.pub4. The number below is exactly as the source gave it.

    Number reported
    -15 percent change
    Which way it went
    Lower
    Likely range
    Not in the abstract
    Source’s own words
    % relative reduction in serum triglycerides vs usual/lower intake
    Who was studied
    Adult
    Compared with
    usual or lower omega-3 intake (placebo or usual diet)
    Amount taken
    0.5 to 5 g/d long-chain omega-3
    For how long
    365 to 2,678 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 reports no confidence interval for the estimateNot 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 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

  • Another kind of study, 2020

    Moderate certainty, level 3 of 4

    Not in this document

    Omega-3 Fatty Acids — Fact Sheet for Health Professionals, NIH Office of Dietary Supplements (ODS); section 'Cardiovascular disease and cardiovascular disease risk factors' (summarizing 2020 Cochrane Review, ref [75]).

    Number reported
    -15 percent change
    Which way it went
    Lower
    Likely range
    Not in this document
    Source’s own words
    percent reduction in serum triglycerides (2020 Cochrane pool, 86 RCTs, n=162,796)
    Who was studied
    Adult
    Compared with
    placebo or control
    Amount taken
    0.5 to 5 g/d
    For how long
    Not in this document
    Disagreement between studies
    Not in this document
    Kind of record
    Government fact sheet
    How this rating was reachedstarts at High, one step down: imprecision
    1. Starts at High
    2. Imprecision brought it down to ModerateThe reason for this step is not on record here.
    3. Ends at ModerateOne step down.
    Not written down for this rating
    risk of bias, indirectness and inconsistency

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

    Published before the signing gate; not yet re-verified.

    Read the source document

  • Another kind of study, 2019

    Moderate certainty, level 3 of 4

    Not in this document

    Omega-3 Fatty Acids — Fact Sheet for Health Professionals, NIH Office of Dietary Supplements (ODS); section 'Recommendations from the American Heart Association' (dose-response from an analysis of 58 trials, ref [90]).

    Number reported
    -5.9
    Which way it went
    Lower
    Likely range
    Not in this document
    Source’s own words
    mg/dL reduction in triglycerides per 1 g/day LC omega-3 (58-trial dose-response)
    Who was studied
    Adult
    Compared with
    placebo or control
    Amount taken
    Recorded detail — g/d
    For how long
    Not in this document
    Disagreement between studies
    Not in this document
    Kind of record
    Government fact sheet
    How this rating was reachedstarts at High, one step down: imprecision
    1. Starts at High
    2. Imprecision brought it down to ModerateThe reason for this step is not on record here.
    3. Ends at ModerateOne step down.
    Not written down for this rating
    risk of bias, indirectness and inconsistency

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

    Published before the signing gate; not yet re-verified.

    Read the source document

  • Systematic review, 2010

    Moderate certainty, level 3 of 4

    Long-chain omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid dose-dependently reduce fasting serum triglycerides.

    Musa-Veloso K, Binns MA, Kocenas AC, et al. Long-chain omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid dose-dependently reduce fasting serum triglycerides (review of 15 RCTs). Nutr Rev. 2010;68(3):155-167. doi:10.1111/j.1753-4887.2010.00272.x. PMID:20384846.

    Number reported
    Not in the abstract
    Which way it went
    Lower
    Likely range
    Not in the abstract
    Source’s own words
    3.1 to 7.2 percent reduction in fasting serum triglycerides at 200-500 mg/day LC omega-3 (15-RCT dose-response model)
    Who was studied
    Adult
    Compared with
    placebo or control
    Amount taken
    Recorded detail — g/d
    For how long
    Not in the abstract
    Disagreement between studies
    Not in the abstract
    Kind of record
    Systematic review and meta-analysis
    How this rating was reachedstarts at High, one step down: imprecision
    1. Starts at High
    2. Imprecision brought it down to ModerateThe reason for this step is not on record here.
    3. Ends at ModerateOne step down.
    Not written down for this rating
    risk of bias, indirectness and inconsistency

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

    Published before the signing gate; not yet re-verified.

    Read the abstract on PubMed

What is still missing from these readings

  • Two give no number at all, only which way it went.
  • Five give no likely range, so how precise those numbers are is unknown.
  • Five do not say how many people took part.
  • For how long — Four of Five readings: Three: Not in this document; One: Not in the abstract.

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

Still to read for Omega-3 fatty acids (EPA/DHA)

Seven of the 19 things on our list for Omega-3 fatty acids (EPA/DHA) have no reading here yet:

  • Alanine aminotransferase (ALT)
  • Cognitive performance
  • Gestational length
  • HDL cholesterol
  • Heart rate variability (RMSSD)
  • High-sensitivity CRP
  • Resting heart rate

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.