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Pooled review (meta-analysis)

Review of 218 pooled analyses: coffee drinking linked to lower risk of death

Poole and colleagues · BMJ (Clinical research ed.) · 2017

Original title: Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes.

Under review. A person has not yet checked this summary against the paper. It is written from the PubMed abstract. Until a person checks it, search engines are asked not to list this page.

What the study found

Points to benefit

Drinking three to four cups a day vs none went with a lower risk of death from any cause (relative risk 0.83, 95% confidence interval 0.79 to 0.88). Heart disease death was also lower (0.81, 0.72 to 0.90).

The study at a glance

Type of study
Pooled review (meta-analysis)
Who or what was studied
218 studies · Adults in many countries, from earlier pooled studies on coffee and health
What was tested
Review of 201 pooled analyses of observational studies and 17 pooled analyses of trials; compared high vs low coffee, any vs none, and one extra cup a day
What it measured
Several kinds of outcomes
Who has a stake
No stake declared
Some authors report fees from drug companies, not coffee makers; no support for this work.
Journal
BMJ (Clinical research ed.), 2017
Source
PubMed record 29167102. This page is based on the abstract only.

How much this study counts

  • ✓Pools the results of 218 studies.
  • •A pooled review is only as strong as the studies it pools.
  • •Measured several kinds of outcomes.
  • ✓No competing interests declared.
  • •Summarized from the PubMed abstract only. The full paper may hold details the abstract leaves out.

✓ Strength– Limit• Note

These points come from fixed rules about the type of study, its size and length, what it measured, and who has a stake. Every study on Digestery gets the same rules.

Where this study sits

This paper is not on the ladder. It is a pooled review (meta-analysis), and reviews and opinion pieces discuss studies that are already counted on the steps below.

↑ Stronger evidence

  1. Trials in people: death from any cause

    0

    Not done yet. This is the step that would answer the question.

  2. Trials in people: other measures

    0

    None among the papers we read.

  3. Trials in people: lab tests or safety

    0

    None among the papers we read.

  4. Population studies

    7

    6 benefit, 1 no difference

  5. Blood levels and genes

    0

    None among the papers we read.

↓ Weaker evidence

  • Points to benefit
  • Mixed
  • No difference
  • No direction
  • Points to harm

How it fits with the other research

The short answer to “Does coffee help you live longer?”

Linked to lower death risk; cause unproven.

Confidence: low. Based on 15 on-topic papers.

Read the full answer
  • Quoted in “What we found”: None of these papers is a trial of coffee and death. Reviews say most data are observational and randomised trials are needed to show cause.
  • Part of the finding “More cups did not keep lowering risk”.
  • Summed up in “What reviews found”: Reviewed 201 pooled analyses of observational research and 17 of trials. Three to four cups a day versus none went with lower death from any cause (relative risk 0.83). It calls for trials to test cause.
  • Open item for a person: Poole 2017 and Ma 2023 authors have drug, supplement or walnut ties, not coffee; marked no stake. Confirm this reading.
  • Open item for a person: Kim 2019 and Poole 2017 may pool overlapping cohorts, possibly including Loftfield 2015; avoid counting them as independent evidence.

Other reviews on this question

See all 15 studies on this question

How this page was made

Label

First read of the abstract
Claude Sonnet
Independent second read
Claude Haiku
Differences settled
The reviewer corrected 3 fields after reading the abstract. Claude Opus 5.5.
Headline
Claude Sonnet, from the checked study record. A script checked its numbers and wording.
Numbers
Checked against the abstract by a script
“How much this study counts”
Fixed rules, the same for every study
Source check by a person
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