Impact of plant-based dietary patterns on obesity-related cancers: the Seguimiento University of Navarra (SUN) prospective cohort.

Evidence suggests that plant-based dietary patterns - favouring plant-based foods without being strictly vegetarian or vegan - may prevent obesity and offer health benefits. Since not all plant-based foods are equally healthy, it is essential to distinguish between healthful and unhealthful plant-based options. This study aimed to analyse the associations between different plant-based dietary patterns and the incidence of obesity-related cancers. We followed-up 16 256 participants from the 'Seguimiento Universidad de Navarra' prospective cohort. Based on a validated FFQ, we calculated adapted overall, healthful and unhealthful plant-based diet index scores. Scores were assessed at baseline and repeatedly after 10 years of follow-up. Hazard ratios (HR) and 95 % CI were estimated using multivariable-adjusted time-dependent Cox regression models. After a median follow-up of 13 years, 221 incident obesity-related cancer cases were confirmed. Overall plant-based and unhealthful plant-based dietary patterns showed no association. Contrarily, participants in the highest tertile of the healthful plant-based diet score had a lower obesity-related cancer risk (HRT3vsT1 0·67; 95 % CI, 0·47, 0·97; Ptrend = 0·031). This association persisted after updating dietary information at 10-year follow-up (HRT3vsT1 0·68; 95 % CI, 0·47, 0·99; Ptrend = 0·037) and was stronger for women (HRT3vsT1 0·52; 95 % CI, 0·32, 0·86; pinteraction = 0·04). In this large prospective cohort, greater alignment with a healthful plant-based dietary pattern was associated with a decreased risk of obesity-related cancer, whereas alignment with overall and unhealthful plant-based dietary patterns showed no association.