The authors of this research note that previous evidence has found that the Mediterranean diet may help improve obesity and offer protection against some types of cancer.

For this study, researchers sought to see how following the Mediterranean diet affected the risk for obesity-linked cancer. They also wanted to explore “the mediating role of body mass index (BMI) and waist-to-hip ratio in the association.”

Researchers used European Prospective Investigation Into Cancer and Nutrition (EPIC) study information. The EPIC study included participants between the ages of thirty-five and seventy from ten countries.

For the current study, they excluded some participants, such as those with cancer at baseline and those with extreme energy intake. In all, they included 450,111 participants in their analysis.

Researchers looked at participants’ diets, focusing on 14 key food groups and nutrients, such as participants’ intake of fish, vegetables, and legumes.

They then estimated how much participants consumed each component daily and their total energy intake.

Researchers also considered data regarding participants’ lifestyles, such as smoking and education level, and body measurements, such as height and weight. BMI was the main indicator for general obesity, and researchers used the waist-to-hip ratio to indicate abdominal obesity.

To see how closely participants adhered to the Mediterranean diet, they used a version of a tool called the MedDiet score. A higher score indicated a higher adherence to the Mediterranean diet, and researchers divided participants into groups of low, medium, and high adherence.

They also calculated another measurement, the relative MedDiet score, which considers olive oil consumption and uses a different scoring method. Participants were scored as having a higher adherence to the Mediterranean diet if they had moderate alcohol consumption.

Researchers performed data analyses, including looking at results without the alcohol component of the scoring. They also looked at how much of the risk reduction in obesity-linked cancer could be explained by BMI and waist-to-hip ratio.

The results revealed distinct benefits for participants who had high adherence to the Mediterranean diet compared to those who had low adherence.

Through the participant follow-up time, which had a median of about 15 years, 4.9% of participants developed obesity-linked cancer. The rates were lowest for the group with the highest Mediterranean diet adherence.

Overall, high adherence to the Mediterranean diet was associated with a 6% risk reduction in obesity-linked cancer.

Researchers also examined specific types of obesity-linked cancer. High adherence to the Mediterranean diet was associated with a lower risk for colorectal, liver, and kidney cancers. Medium adherence was associated with a lower risk for esophageal cancer.

Following the Mediterranean diet appeared to offer distinct risk reduction for participants who were former or current smokers.

Among women, researchers did not identify an association between the Mediterranean diet and risk for postmenopausal breast cancer, endometrial cancer, or ovarian cancer.

The study results do have limitations. For one, the study included participants from European countries who were in a specific age range at enrollment, so the results cannot be generalized to other populations.

Data from additional countries and populations could be helpful in future research. Dietary data and other components were from participant reports, which are not always correct. Some countries also had participants self-report components like height and weight, which could introduce bias.

Additionally, diet and potential confounders were only evaluated once, and it is possible that changes could have happened throughout the follow-up timeframe.

The authors further admit that the scoring they used might not totally reflect the Mediterranean lifestyle pattern, but this is more likely to increase bias toward underestimation.

The MedDiet score system also has the problem of treating the nutritional components like they are all equally important and then noting if someone consumes more or less than a particular measurement.

About 70% of the participants were women, so including more men in future analyses might be helpful.

More research may be required to explore the reasons for the associations that the study authors observed. Researchers acknowledge a few possible reasons for why they did not find BMI or waist-to-hip ratio mediated the benefits of the Mediterranean diet, and one is that the cohort had a low prevalence of obesity.

The other possibility was “the distinct contribution of general vs. abdominal obesity to metabolic disruptions.” Overall, more research and follow-up may be helpful in this area.

Study author Inmaculada Aguilera-Buenosvinos, a doctoral researcher in the Department of Preventive Medicine and Public Health at the Navarra Institute for Health Research, University of Navarra in Pamplona, Spain, noted the following continued research in this area to Medical News Today:

Even with all these caveats, the current study emphasizes a potential long-term benefit of following the Mediterranean diet.

Anton Bilchik, MD, PhD, a surgical oncologist, chief of medicine, and Director of the Gastrointestinal and Hepatobiliary Program at Providence Saint John’s Cancer Institute in Santa Monica, CA, who was not involved in the study, told MNT that this research “provides further evidence [of] how important a healthy diet low in fat, high in protein and vegetables [and] eliminating processed food is in reducing the risk of getting cancer.”

The data may also affect how medical professionals discuss dietary components with patients. Wael Harb, MD, a board-certified hematologist and medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, CA, likewise not involved in the research, noted that:

“From a clinical perspective, this study supports integrating dietary counseling into cancer prevention strategies, particularly for patients at high risk due to obesity or metabolic disorders. Encouraging adherence to the Mediterranean diet could serve as a non-pharmacologic, lifestyle-based intervention to reduce cancer risk. This approach complements existing prevention strategies, such as weight management and exercise, and highlights the role of nutrition as a modifiable factor in cancer risk reduction. Clinicians should consider incorporating dietary education into patient care, emphasizing long-term adherence to healthy eating patterns.”