Acceptability and impact on health-related markers of a sustainable dietary pattern: results from a pilot randomized controlled cross-over study

Purpose Well-balanced plant-based diets can promote health and reduce environmental impact. However, evidence from interventional studies remains limited. This pilot intervention study aimed to provide exploratory insights into potential challenges associated with the EAT-IT dietary pattern, an adaptation of the EAT-Lancet Healthy Reference Diet. Methods Nine subjects (mean age 26 ± 2 years, 5 females) participated in a 6-week randomized controlled cross-over trial. Participants followed two isocaloric interventions: the EAT-IT dietary pattern and a control diet based on the Italian Food-Based Dietary Guidelines. Dietary intake was recorded using 7-day food records. Anthropometric measurements and metabolic parameters were collected according to standardized and validated protocols. Gut microbiota was analyzed through 16 S rRNA gene sequencing and taxonomic profiling. Acceptability was evaluated via a validated questionnaire. Results Nutritional analysis showed that the EAT-IT pattern significantly increased fiber intake from 11.3 ± 5.2 to 15.1 ± 4.2 g/1000 kcal and ω-6 fatty acid intake from 5.7 ± 2.2 to 6.6 ± 1.9 g/day (p < 0.05 for interaction). Regarding metabolic markers, a significant within-group reduction (p < 0.05) was observed for fasting insulin (8.4 ± 2.2 to 6.5 ± 2.2 µU/mL) and HOMA1-IR (2.0 ± 0.6 to 1.5 ± 0.5). Changes in gut microbiota were also observed, specifically an increase in Bacteroides and a decrease in Coriobacteriaceae. While generally well-accepted, participants reported a higher perceived effort for EAT-IT, particularly regarding legume preparation. Conclusion Despite the small sample size, this pilot study offers relevant insights into key aspects of sustainable plant-based diets, underscoring the necessity for further investigation.