(P06-013-25) Impact of Ultra-Processed and Minimally Processed Diets Following UK Dietary Guidance on Quality of Life: A Randomised, Cross-Over, Controlled Feeding Clinical Trial

Objectives: To compare changes in quality of life between 8-week minimally processed food (MPF) and ultra-processed food (UPF) diets following UK Eatwell Guide (EWG) dietary recommendations.

Methods: This is a 2x2 crossover randomised controlled feeding trial. Inclusion criteria included age ≥18, body mass index ≥25 and < 40 kg/m², and ≥50% of habitual dietary intake from UPF. Participants were provided with an ad libitum 8-week MPF diet and an 8-week ad libitum UPF diet, both following EWG dietary recommendations, in a random order. Diets were delivered to participants’ homes. Participants were not informed of the food processing groups. Allocation was not concealed from researchers.

Quality of life outcomes included within-participant differences in EuroQol five-dimensions three-levels (EQ-5D-3L), Impact of Weight on Quality of Life Lite (IWQoL-Lite), Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS), Patient Health Questionnaire-9 (PHQ-9) and Generalised Anxiety Disorder-7 (GAD-7) at 8 weeks between UPF/MPF diets. Mixed-effects models were used to assess changes in outcomes. The trial was prospectively registered (NCT05627570).

Results: Between April 2023 and May 2024, 55 individuals were recruited (n=28 to MPF then UPF, n=27 to UPF then MPF diet); 50 participants comprised the intention-to-treat sample. At 8 weeks, IWQoL-Lite (MPF: 7.4 (95% confidence interval (95%CI): 2.8, 11.9); UPF: 7.3 (95%CI: 2.6, 11.9)) and WEMWBS (MPF: 3.3 (95% confidence interval (95%CI): 0.2, 6.4); UPF: 3.3 (95%CI: 0.2, 6.4)) were significantly higher on both diets compared with baseline. PHQ-9, GAD-7 and EQ-5D-3L were not significantly different at 8 weeks from baseline on either diet. There were no significant differences in any of the changes in quality of life outcomes between diets from baseline to week 8 (IWQoL-Lite: p = 0.951; WEMWBS p = 0.981; PHQ-9: p = 0.803; GAD-7: p = 0.816; EQ-5D-3L: p = 0.445).

Conclusions: Eight weeks of diets following national dietary guidance resulted in neutral or favourable changes in markers of quality of life, with no significant differences between diets. The results have implications for understanding the mental health impact of food processing.

Funding Sources: National Institute for Health and Care Research Biomedical Research Centre and Rosetrees Trust