Dairy
Also called: milk, cheese, yoghurt.
Last reviewed 2026-09-22. How this works.
Either direction Grade C
Human evidence exists and does not settle it.
Studies of dairy point one way for bowel cancer and the other way for prostate, and neither is settled.
Lower bowel cancer risk. The prostate signal was downgraded in 2018.
The claim
Dairy is claimed both to cause cancer and to protect against it, often by the same person on different days.
What it does
Mechanisms have been proposed in both directions and none of them settles the question. What this entry rests on is what was counted in people who were already eating what they ate.
The evidence
Two reviews within the World Cancer Research Fund’s Continuous Update Project pooled the cohort studies. The bowel cancer review found a lower risk among people with higher intakes of total dairy and of milk. The register cannot hand you that review: no DOI or PubMed number for it is recorded, so it is listed below with nothing to look it up by.1
The prostate review pooled thirty-two studies and found a small association running the other way: more total dairy, slightly more prostate cancer.2
What happened to that prostate finding afterwards matters more than the finding, and it is the part of this entry most people arrive looking for. In the 2018 Third Expert Report the evidence was downgraded from probable to limited — the panel saying it no longer held the association to be well enough established to call it likely.3
Both reviews pooled studies that followed what people already ate. Nobody was assigned dairy or kept from it, so whatever else was different about the people who drank more milk is still inside the answer. Every effect size published in this literature is expressed per quantity of intake, and none of them is reproduced here.12
The studies this rests on
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Pooled cohort studies of dairy products and colorectal cancer risk1
A meta-analysis, summarising observational studies, measured a clinical outcome.
reduced colorectal cancer risk with intakes of total dairy products and milk.
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Pooled cohort studies of dairy products, calcium and prostate cancer risk2
A meta-analysis, summarising observational studies, measured a clinical outcome.
a small positive association between total dairy intake and prostate cancer, across thirty-two studies.
What is absent
Nobody has been assigned dairy, or asked to go without it, in a trial with a cancer endpoint. Both reviews behind this entry pooled studies that recorded what people were already doing.
Scope: dairy intake with a cancer endpoint.
Established by published review, the two Continuous Update Project meta-analyses recorded in chapter 10 note 14, checked 2026-09-22. Result: both are systematic reviews and meta-analyses of cohort studies.12
What to ask
Is there any part of my diet you would actually want me to change?
The dish-to-person gap
Dairy is eaten as food rather than taken as a measured compound, and the register holds no human pharmacokinetic measurement for it.
When to call your team — no warning signs are recorded
If you have changed how you eat because of something you have read, or are thinking about it, the people treating you can only weigh that if they know about it. That is true when nothing has been written down here, and it is most true then.
The register records no warning signs for this entry. That is not a statement that nothing can go wrong.
Interactions
The register holds no measured interaction between this food and a cancer treatment class. An empty list means nobody has measured it, not that nothing would happen. Concentrated extracts are a different question from the food.
Nobody having looked is not the same as nothing being there. That is what this line says and all it says.
The whole interaction list, and how to turn it into a pharmacy review request.
Find a trial instead
This is an ordinary food rather than an intervention with recruiting trials attached.
References
Aune D, Lau R, Chan DS, et al. Dairy products and colorectal cancer risk: a systematic review and meta-analysis of cohort studies. Annals of Oncology 2012;23:37-45.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 10 note 14. The author string is abbreviated in the source that was read and has not been expanded.
Aune D, Navarro Rosenblatt DA, Chan DS, Vieira AR, Vieira R, Greenwood DC, Vatten LJ, Norat T. Dairy products, calcium, and prostate cancer risk: a systematic review and meta-analysis of cohort studies. American Journal of Clinical Nutrition 2015;101(1):87-117.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 10 note 14.
A systematic review in the British Journal of Nutrition, 2022, recording the downgrading of the prostate evidence from probable to limited in the 2018 World Cancer Research Fund and American Institute for Cancer Research Third Expert Report.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 10 note 14.