Food processing and risk of central nervous system tumours: A preliminary case-control analysis from the MEditerranean DIet in relation to CancEr of brAin (MEDICEA) study

Background: The relationship between diet and central nervous system (CNS) tumours was almost exclusively focused on food composition. We evaluated the relationship of different degrees of food processing with risk of CNS tumours.

Methods: The study sample included 44 CNS tumours cases (20 non-malignant and 24 malignant) recruited from the Neurosurgery Department at the IRCCS Neuromed (Italy), and 88 controls matched 1:2 for sex and age± 10 years, identified from the Moli-sani Study. Dietary intake was assessed using a 188-item FFQ. Food items were grouped according to the NOVA classification on the basis of processing as: (1) unprocessed/minimally processed foods; (2) processed culinary ingredients; (3) processed foods; and (4) ultra-processed food (UPF). Conditional logistic regression models were used to estimate odds ratio (OR) and 95% confidence intervals (95%CI) of dietary contributions from each NOVA group (as weight ratio on the total food eaten) and adjusting for potential confounders.

Results: In a multivariable conditional to match logistic regression analysis also controlled for overall diet quality, 1% increment in UPF intake was associated with higher odds of all CNS tumours (OR = 1.06; 1.01-1.13), particularly of malignant CNS tumours (OR = 1.11; 1.02-1.22), while no association with non-malignant CNS tumours was found (OR = 1.06; 0.99-1.15). In contrast, only processed food was inversely associated with risk of both CNS tumours overall (OR = 0.94; 0.90-0.98) and of malignant CNS tumours (OR = 0.90; 0.83-0.96).

Conclusion: Increasing UPF intake was associated with higher risk of CNS tumours, especially malignant ones, independently of the overall diet quality, while only processed food (but not UPF) was inversely related to the risk of this disease.