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Pooled review (meta-analysis)

Pooled review of 197 studies: no clear link between red meat and breast cancer

Poorolajal and colleagues · Journal of research in health sciences · 2021

Original title: Factors for the Primary Prevention of Breast Cancer: A Meta-Analysis of Prospective Cohort Studies.

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

No difference

For red meat and breast cancer, the risk ratio was 1.05 (1.00, 1.11). The range touches 1.00, so no clear link.

The study at a glance

Type of study
Pooled review (meta-analysis)
Who or what was studied
197 studies, 19,413,702 people · Women in 197 long-term studies of 15 factors and breast cancer
What was tested
Red meat eating (comparison groups not stated in abstract), one of 15 factors checked
What it measured
The question itself: cancer, heart disease and death
Who has a stake
No disclosure in PubMed
No disclosure in PubMed.
Journal
Journal of research in health sciences, 2021
Source
PubMed record 34698654. This page is based on the abstract only.

How much this study counts

  • ✓Pools the results of 197 studies with 19,413,702 people.
  • •A pooled review is only as strong as the studies it pools.
  • ✓Measured the question itself: cancer, heart disease and death.
  • •The PubMed record has no conflict-of-interest statement.
  • •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: cancer and heart disease

    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

    6

    2 benefit, 4 harm

  4. Population studies

    12

    1 benefit, 2 mixed, 1 no difference, 8 harm

  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 red meat raise cancer and heart disease risk?”

Linked to higher risk, especially processed meat.

Confidence: low. Based on 30 on-topic papers.

Read the full answer

Other reviews on this question

See all 30 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 1 field 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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