The global prevalence of excess body weight and related cancer risks has risen significantly. From 1975 to 2016, adult obesity rates nearly doubled (21% in males and 24% in females), with 30% currently classified as obese population. Obesity is associated with an increased risk of cancer at 13 different anatomic sites, such as the esophagus, breast, kidney, endometrium, and liver.
The Mediterranean diet (MedDiet) is associated with weight loss and a reduced risk of obesity-related cancers (ORCs). This association was well demonstrated in the current article published in JAMA Network Open. This prospective cohort study explored this association by evaluating the MedDiet score (MDS) and the mediating effect of adiposity.
Data were collected from the European Prospective Investigation into Cancer and Nutrition (EPIC) study in which 521,324 individuals (age range = 35 to 70 years) were enrolled between 1992 and 2000 from 23 sites in 10 countries (France, Greece, Sweden, the Netherlands, Spain, UK, Denmark, Germany, Italy, and Norway). Patients with cancer at baseline, extreme energy intake ratios (top and bottom 1%), and missing information on diagnosis, diet, lifestyle, and follow-up were excluded.
Dietary intake before baseline was evaluated at the time of enrollment by a validated country-specific questionnaire. Adherence to MedDiet was assessed using a 9-point scale and classified as low (0-3 points), medium (4-6 points), and high (7-9 points). The correlation between ORC incidence and MedDiet adherence was measured using a multivariable Cox proportional hazards regression analysis. The relationship between body mass index (BMI) and waist-to-hip ratio was determined by mediation analysis.
After applying inclusion and exclusion criteria, 450,111 individuals (mean age = 51.1±9.8 years, 29.2% male, 70.8% female, mean BMI = 25.3±4.2 kg/m2) were included in this cohort study. The median follow-up period was 14.9 years (Interquartile range [IQR] = 4.1).
This study results showed that 4.9% of participants developed ORCs with incidence rates of 0.053 per person in the low, 0.049 in the medium, and 0.043 in the high MedDiet adherence groups. The high MedDiet adherence group experienced lower ORC risk compared to the low MedDiet adherence group, with a hazard ratio (HR) of 0.94 (95% confidence interval [CI], 0.90-0.98). Similar values were observed for the association between the medium MedDiet adherence group and ORCs with P < 0.001. While no correlation was found when MDS was modeled continuously with an HR of 0.94 (95% CI, 0.81-1.11).
In site-specific ORCs, there was an inverse relationship observed between the high MDS and risk of cancers related to kidney (HR, 0.67; 95% CI, 0.55-0.82), hepatocellular (HR, 0.52; 95% CI, 0.33-0.83) and colorectal (HR, 0.92; 95% CI, 0.85-0.99). Whereas medium MDS was inversely correlated with esophageal cancer (HR, 0.66; 95% CI, 0.48-0.93). The statistical non-significance difference was observed for multiple myeloma (HR, 0.90; 95% CI, 0.81-1.01, P = 0.44).
In both sexes, a lower risk of ORCs was observed in participants with medium or low MedDiet adherence (men: HR, 0.93 [95% CI, 0.89-0.97]; women: HR, 0.97 [95% CI, 0.95-1.00]; P for interaction = 0.01). Meditate on the analysis found no association between MedDiet adherence (high vs. medium MDS) and ORCs risk mediated by waist-to-hip ratio or BMI.
This study’s limitations include assessing exposure and confounders only at baseline, incomplete capture of the Mediterranean lifestyle, potential bias in outcome measures, especially in France and Norway, and the low prevalence of obesity.
In conclusion, this study suggests that higher MedDiet adherence may slightly lower the risk of ORCs, whereas medium adherence is linked to a modest risk reduction of cancer. However, no evidence of mediation through obesity was found. Hence, further research is needed to explore the underlying mechanisms through which MedDiet may influence the risk of ORCs.
Reference: Aguilera-Buenosvinos I, Morales Berstein F, González-Gil EM, et al. Adherence to the Mediterranean Diet and Obesity-Linked Cancer Risk in EPIC. JAMA N tw Open. 2025;8 2):e2461031. doi:10.1001/jamanetworkopen.2024.61031
