Minimally processed foods have a higher total antioxidant content compared to processed and ultra-processed foods: results from an analysis of 1946 food items

Ultra-processed foods (UPF), per the NOVA Classification, provide a major source of calories within modern food systems and are associated with poor health outcomes related to chronic inflammation. Dietary antioxidants play a key role in preventing disease; however, the relationship between the NOVA Classification and the total antioxidant content (TAC) of foods is not well characterised. We hypothesised that TAC would be highest in minimally processed food (MPF), lower in processed food (PRF) and lowest in UPF. TAC data for 3137 animal-based, mixed and plant-based food items were obtained from a published dataset. After data cleaning, 1946 food items and their TAC values were analysed using two hierarchal linear models (alpha: <i>P</i> < 0·05). MPF had the highest mean TAC (10·79 (sem 0·87) mmol/100 g) and were 11·31-fold and 10·72-fold higher than PRF and UPF, respectively (<i>P</i> = 0·023). Plant-based and mixed foods had a higher mean TAC (8·55 (sem 0·68) and 1·12 (sem 0·11) mmol/100 g, respectively) and were 22·67-fold and 2·98-fold higher compared with animal-based foods (<i>P</i> < 0·001). Food processing did not change mean TAC in mixed and animal-based foods; however, plant-based MPF had a higher mean TAC (11·49 (sem 0·93) mmol/100 g) and were 9·88-fold and 15·12-fold higher compared with plant-based PRF and UPF, respectively (<i>P</i> < 0·001). Mean TAC differed between NOVA processing groups for three categories of food: vegetables, beverages and beans, nuts and seeds (<i>P</i> < 0·001). Across all food items, and especially plant-based foods, mean TAC decreased with food processing. The lower TAC of UPF may at least partially explain why their consumption promotes inflammatory chronic disease.