Planetary health diet index and risk of irritable bowel syndrome: a prospective cohort study

The EAT-Lancet Commission introduced the planetary health diet to promote human health while reducing environmental impact. However, no study has yet examined how adherence to this diet is associated with risk of irritable bowel syndrome (IBS).

This study aimed to investigate the association between the planetary health diet index (PHDI) and the risk of developing IBS.

This prospective cohort study included 177,754 participants (mean age: 55.6 ± 7.93 years, 44.8% males) free of IBS at baseline from the UK Biobank who completed at least one 24-h dietary assessment in 2009-2012. Adherence to the PHDI was quantified using a diet score ranging from 0 to 140 points. Incident IBS was identified through electronic health records. Cox proportional hazards models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between the PHDI and IBS risk.

During a median follow-up of 10.5 years, 2684 IBS cases were documented. In the fully adjusted model, participants in the highest PHDI quartile had a significantly lower risk of incident IBS compared with those in the lowest quartile (HR = 0.73; 95% CI: 0.66, 0.82; P for trend < 0.0001); the corresponding HR (95% CI) per 10-point increase was 0.92 (0.89, 0.95). Sensitivity and subgroup analyses yielded generally consistent results. In addition, such inverse association was more pronounced among participants aged < 60 years and females than their counterparts (P for interaction < 0.05).

Higher adherence to the PHDI was associated with a lower risk of incident IBS, providing further evidence that adherence to the planetary health diet may benefit gastrointestinal health.