(P05-29-26) Ultra-Processed Food Classification, Hyper-Palatability, and Energy Density of Vegan and Omnivorous Diets in the TwiNS Randomized Controlled Trial

Objectives: To evaluate ultra-processed food (UPF) classification, hyper-palatability (HP), and energy density (ED) in high quality vegan (VEG) and omnivorous (OMN) diets as potential factors driving food consumption.

Methods: Nutrition Data System for Research nutrient reports derived from 24-hour dietary recalls of 22 pairs of identical twins who followed an 8-week VEG or OMN diet were analyzed to estimate and compare UPF content, HP, and non-beverage ED. UPF classification was supported by a supervised machine learning model trained on ingredient list based on the NOVA Classification System, with subsequent validation by a research dietitian. HP foods were identified using previously published criteria on thresholds for high fat, sodium, sugar, and carbohydrate content. ED was estimated in kcal/g. Independent and paired t-tests were used to compare food characteristics between and within diet groups, respectively, at 4-week and 8-week timepoints.

Results: Of 44 participants (77% female, mean±SD age 39.6±12.7 years, body mass index 25.9±4.7 kg/m²), mean±SEM % energy from UPF decreased in both diet groups from baseline to week 4: 24±2% to 19±2% in VEG; 24±2% to 12±1% in OMN (both P< 0.001), with significant between-group differences observed at this timepoint. At week 8, % energy from UPF further declined in VEG (16±2%), while increasing in OMN (20±2%; both P< 0.01). Percent energy from HP foods similarly decreased from baseline to week 4 within groups (-13±2% in both groups, P< 0.001), but only differed between groups at week 8 (14±1% in VEG vs 19±1% in OMN, P< 0.01). In participants following the VEG diet only, mean non-beverage ED decreased significantly from baseline to weeks 4 and 8. A trend toward lower ED in the VEG vs OMN was observed at week 4, corresponding to very-low and low ED classifications, respectively.

Conclusions: UPF, HP, and ED were all lower when following a VEG compared to OMN diet pattern, despite both diets being designed to be high in dietary quality. As UPF, HP, and ED characteristics may influence food choice and intake beyond diet quality, these factors warrant consideration as possible mechanisms affecting metabolic risk factors, as assessed in other published TwiNS analyses.

Funding Sources: This research was supported by the National Heart, Lung, and Blood Institute.