Mediterranean pattern
Also called: Mediterranean diet, PREDIMED diet.
Last reviewed 2026-09-16. How this works.
Preventing cancer Grade B
Good human evidence, with a limit worth knowing.
A large food trial found fewer breast cancers in the group eating this way, though that was not what the trial set out to measure.
Randomised evidence, on a secondary endpoint, in a trial that was later corrected.
The claim
The claim is that eating the way people eat around the Mediterranean lowers the risk of getting cancer.
What it does
No single component carries this. It is a pattern of eating rather than an ingredient, which is part of why it is hard to study and part of why it is more believable than a claim for one food.
The evidence
PREDIMED is the reason this entry is graded above the rest of the diet chapter: it randomly assigned people to a way of eating and followed them, rather than asking them later what they had eaten. Among women at high cardiovascular risk, invasive breast cancer was less frequent in the group assigned the Mediterranean pattern with extra-virgin olive oil.1
Two things keep it at B rather than higher. Breast cancer was a secondary endpoint, not what the trial was built to answer. And PREDIMED was later retracted and republished after its own authors found protocol deviations, including participants who were not randomised, with several derivative papers corrected.231
The screening method that caught it is worth understanding rather than cheering. It was applied to 934 trial reports in one journal and flagged eleven. On review, five were a units mix-up, five were most likely limitations of the method itself, and one was real. A method that finds eleven suspicious papers and one real problem is a useful screen and not a verdict.2
The studies this rests on
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PREDIMED, Mediterranean diet and invasive breast cancer1
A randomised trial, open label, measured a clinical outcome.
fewer invasive breast cancers in the Mediterranean diet with extra-virgin olive oil group, on a secondary endpoint.
What is absent
No second randomised trial has tested this pattern against a cancer endpoint. The finding rests on one trial, on a secondary endpoint, and that trial needed correcting.
Scope: the breast cancer finding.
Established by trial scope, checked 2026-09-16. Result: PREDIMED is the only randomised trial with a cancer endpoint in this record.12
What to ask
Is there anything about how I eat that you would want me to change during treatment?
Treating existing cancer Grade C
Human evidence exists and does not settle it.
Eating well after a cancer diagnosis is worth doing, but the big trials did not show that it changed the cancer.
Evidence that a diet prevents a cancer does not transfer to treating one.
The claim
The claim is that if this way of eating lowers the risk of getting cancer, it should also help someone who already has one.
What it does
This is the assumption the chapter is built to break. Preventing a cell from becoming cancerous over decades and changing the behaviour of a tumour that already exists are different problems, and evidence for one is not evidence for the other.
The evidence
Two large randomised trials tested dietary change in women who had already been treated for breast cancer. They tested related patterns rather than the Mediterranean pattern itself, which is worth stating plainly.45
The first, WINS, randomised 2,437 women to reduce dietary fat and reported fewer relapses in the diet group. The benefit was no longer statistically significant at longer follow-up, and there was no effect on overall survival. Mean body weight was also lower in that group, which makes it hard to say what the diet itself did.4
The second, WHEL, randomised 3,088 women to a diet very high in vegetables, fruit and fibre and low in fat. It found no effect on breast cancer relapse or survival over an average of more than seven years.5
The studies this rests on
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WINS, dietary fat reduction after breast cancer4
A randomised trial, open label, measured a clinical outcome, 2437 participants.
fewer relapses in the dietary group at interim analysis; not significant at longer follow-up and no effect on overall survival.
hazard ratio 0.76, interval 0.6 to 0.98. relapse; overall survival hazard ratio 0.89, interval 0.65 to 1.21
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WHEL, high vegetable, fruit and fibre diet after breast cancer5
A randomised trial, open label, measured a clinical outcome, 3088 participants.
no effect on breast cancer relapse or survival.
What is absent
No randomised trial has tested the Mediterranean pattern itself as a treatment for an existing cancer. The two trials here tested a low-fat diet and a high-vegetable diet, which are related but not the same thing.
Scope: the Mediterranean pattern specifically, in people already diagnosed.
Established by trial scope, checked 2026-09-16. Result: neither randomised trial in this record assigned the Mediterranean pattern.45
What to ask
Does what I eat make any difference to how my cancer behaves, or is this about keeping me well through treatment?
The dish-to-person gap
This is a way of eating rather than a compound that reaches a concentration in the blood, so the dish-to-person comparison does not apply to 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.
Interactions
A way of eating is not checked against treatment classes in this register.
The whole interaction list, and how to turn it into a pharmacy review request.
Find a trial instead
This is a general dietary pattern rather than an intervention with recruiting trials attached.
References
Toledo E, Salas-Salvado J, Donat-Vargas C, et al. Mediterranean diet and invasive breast cancer risk among women at high cardiovascular risk in the PREDIMED trial: a randomized clinical trial. JAMA Internal Medicine 2015;175(11):1752-1760.
doi:10.1001/jamainternmed.2015.4838
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 9 note 7. The author string is abbreviated in the source that was read and has not been expanded.
Editor's Note, New England Journal of Medicine, accompanying the retraction and republication of the PREDIMED trial, 13 June 2018. Republished paper: Estruch R, Ros E, Salas-Salvado J, et al, New England Journal of Medicine 2018;378(25):e34.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 9 note 2.
Protocol deviations and reanalyses in derivative studies of the PREDIMED trial. JAMA Internal Medicine 2018;178(12):1731-1732.
doi:10.1001/jamainternmed.2018.6460
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 9 note 4.
Chlebowski et al. Dietary fat reduction and breast cancer outcome: interim efficacy results from the Women's Intervention Nutrition Study. Journal of the National Cancer Institute 2006;98(24):1767.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 9 note 5. The author string is abbreviated in the source that was read and has not been expanded.
Pierce JP, Natarajan L, Caan BJ, et al. Influence of a diet very high in vegetables, fruit, and fiber and low in fat on prognosis following treatment for breast cancer: the Women's Healthy Eating and Living (WHEL) randomized trial. JAMA 2007;298(3):289-298.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 9 note 6. The author string is abbreviated in the source that was read and has not been expanded.