Meta-analysisindependent cross-checkabstract checked I-DRY-111 standard review
Ovarian cancer and dairy: mixed signals
Effects of dairy products, calcium and vitamin D on ovarian cancer risk: a meta-analysis of twenty-nine epidemiological studies.
Overview
Liao MQ et al.. Br J Nutr 2020 · PMID 32189606 · DOI 10.1017/S0007114520001075
Whole milk linked to higher risk (RR 1.35), low-fat milk and cheese to lower risk.
Does the study support the specific claim? Partly · Methodological quality: low
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Summarise dairy and ovarian cancer studies.
- How was the study done?
Meta-analysis.
- How many people, animals or samples were studied?
29 studies.
- What was actually found?
Mixed: whole milk up, low-fat milk and cheese down.
- How large was the observed effect?
Total dairy RR 1.03 per 100 g/day.
- What do the results mean in everyday life?
No clear message that dairy causes ovarian cancer.
- What are the study's limitations?
Mixed designs; possible bias.
- What does it say about Elawady's specific claim?
Partly supports, partly contradicts.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
Cannot prove any causal effect.
Scientific in-depth review
1. Full reference
- Authors
- Liao MQ et al.
- Journal
- Br J Nutr
- Year
- 2020
- Identifier
- PMID 32189606 DOI 10.1017/S0007114520001075
- Verification
- verified – PubMed efetch 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
Are dairy, calcium and vitamin D associated with ovarian cancer?
3. Study design and population
- Study design
- Meta-analysis – Systematic review and meta-analysis of case-control and cohort studies (5 databases to 24 Dec 2019)
- Population
Women in 29 studies
- Country
Multinational
- Period
to 2019
- Sample size
29 studies
- Inclusion and exclusion criteria
Case-control or cohort studies
4. Methods and endpoints
- Exposure / intervention
Dairy types, calcium, vitamin D
- Comparator
Lowest intake
- Endpoints
Ovarian cancer
- Statistical methods
Pooled RR, high v low and per 100 g/d
5. Actual results
- Results
High v low: whole milk RR 1.35 (1.15-1.59); low-fat milk 0.84 (0.73-0.96); dietary calcium 0.71 (0.60-0.84); dietary vitamin D 0.80 (0.67-0.95). Per 100 g/d: total dairy 1.03 (1.01-1.04); whole milk 1.07 (1.03-1.11); low-fat milk 0.95 (0.91-0.99); cheese 0.87 (0.76-0.98).
- Absolute risks
not reported
- Authors' conclusion
Whole milk intake might contribute to a higher ovarian cancer risk, whereas low-fat milk, dietary calcium and vitamin D might reduce the risk.
6. Strengths
- Many studies
- Type-specific analyses
7. Weaknesses
- Mixes case-control (recall bias) and cohort
- Opposite directions for similar foods suggest confounding
- Abstract only
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Design mixing; heterogeneity not in abstract.
9. Assessment of the statistical interpretation
Per 100 g/d total dairy RR 1.03 is very small; the cheese estimate points the other way.
10. Relevance to the specific claim
Partly supports a whole-milk association, but low-fat milk and cheese were inversely associated, so dairy as a whole is not shown to cause ovarian cancer.
11. Independent contrary findings
A-DRY-05 (pooled cohorts: no association for dairy foods).
12. Transferability to Germany and Europe
Mostly Western populations.
13. Overall methodological judgement
Inconsistent, low-certainty evidence; does not support a general claim.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | low |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | unknown |
| Consistency with the overall evidence | inconsistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Cohort-only analyses.
15. Linked fact checks
- Dairy and lactose increase ovarian cancer risk (about 19% higher; serous ovarian cancer doubled in heavy milk drinkers). – Studies with mixed or unclear results