Adherence to the Mediterranean diet is associated with reduced risk of head and neck, gastric, and liver cancers: a systematic review and meta-analysis.

The Mediterranean diet (MedDiet) is well established for its cardiometabolic benefits and has increasingly been linked to reduced cancer risk. While protective associations with colorectal cancer are consistently reported, evidence for other gastrointestinal and upper aerodigestive malignancies remains less comprehensively synthesized. We conducted a systematic review and meta-analysis to quantify the association between adherence to the Mediterranean diet and the risk of head and neck, gastric, and liver cancers. A systematic search of PubMed, Web of Science, and Scopus was performed for observational studies published through September 2025. Prospective cohort and case-control studies reporting relative risk (RR), odds ratio (OR), or hazard ratio (HR) estimates comparing highest versus lowest MedDiet adherence were eligible. Pooled risk estimates were calculated using random-effects models. Thirty-four studies comprising 4,286,835 participants were included. High adherence to the Mediterranean diet was associated with significantly reduced risk of head and neck cancer (RR = 0.55; 95% CI = 0.45-0.67), gastric cancer (RR = 0.62; 95% CI = 0.53-0.73), and liver cancer (RR = 0.59; 95% CI = 0.53-0.67). Substantial heterogeneity was observed for head and neck (I2 = 90%) and gastric cancer (I2 = 76%), whereas heterogeneity was moderate for liver cancer (I2 = 35%). In conclusion, high adherence to the Mediterranean dietary pattern is associated with lower risk of head and neck, gastric, and liver cancers. Together with prior evidence for colorectal cancer, these findings support the Mediterranean diet as a cornerstone of dietary cancer prevention strategies. However, heterogeneity across studies and reliance on self-reported dietary assessment warrant cautious interpretation.