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Gene study (Mendelian randomization)

Gene study of 512,715 adults: gene-predicted drinking linked to stroke but not heart attack

Millwood and colleagues · Lancet (London, England) · 2019

Original title: Conventional and genetic evidence on alcohol and vascular disease aetiology: a prospective study of 500 000 men and women in China.

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What the study found

Mixed

Self-reported drinking had U-shaped links with stroke and heart attack. Gene-predicted drinking raised stroke risk (RR per 280 g per week 1·27, 1·13-1·43 for ischaemic stroke) but not heart attack (RR 0·96, 95% CI 0·78-1·18).

The study at a glance

Type of study
Gene study (Mendelian randomization)
Who or what was studied
512,715 people · 512,715 Chinese adults; about a third of men drank most weeks, very few women
What was tested
Self-reported drinking (about 100 g a week) and gene-predicted drinking (4 to 256 g a week), followed about 10 years
What it measured
The question itself: heart disease and death
Who has a stake
Company stake
No disclosure in PubMed; funders include GlaxoSmithKline, not an alcohol maker.
Journal
Lancet (London, England), 2019
Source
PubMed record 30955975. This page is based on the abstract only.

How much this study counts

  • •A gene study: it uses natural gene differences as a kind of experiment. It is less affected by lifestyle than surveys, but it rests on assumptions that can fail.
  • ✓Large: 512,715 people.
  • ✓Measured the question itself: heart disease and death.
  • –Company stake: No disclosure in PubMed; funders include GlaxoSmithKline, not an alcohol maker.
  • •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

Each dot is one on-topic paper on this question. Steps near the top answer the question more directly.

↑ Stronger evidence

  1. Trials in people: 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

    0

    None among the papers we read.

  4. Population studies

    5

    3 benefit, 1 mixed, 1 harm

  5. Blood levels and genes

    6

    1 mixed, 2 no difference, 3 harm

    ↑ This study is the ringed dot

↓ Weaker evidence

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

How it fits with the other research

The short answer to “Is moderate drinking good or bad for your heart?”

Not shown to help; may harm.

Confidence: very low. Based on 21 on-topic papers.

Read the full answer

Of the other 5 papers on the same step: 2 no difference, 3 harm. This one found mixed. It differs from most of them.

  • Quoted in “What we found”: Population studies often link light to moderate drinking with fewer heart attacks and heart deaths than not drinking. These studies show links, not causes.
  • Quoted in “What we found”: Gene studies, built to reduce bias, found no protection from moderate drinking. Several tied more drinking to higher stroke or heart disease risk; pooled gene data showed no link.
  • Part of the finding “Gene studies find no protection, and stroke harm”.
  • Marked as a key paper in the research timeline: Gene study of 500 000: drinking raises stroke risk.
  • Open item for a person: Millwood 2023 and Millwood 2019 use the same China Kadoorie Biobank cohort; count once.
  • Open item for a person: Stake set to company for GlaxoSmithKline funding (Millwood 2023, Millwood 2019); a drug maker, not alcohol. Confirm rule intent.

Other papers on the same step

See all 21 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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