Association between the planetary health dietary index and risk of multiple long-term conditions

Objectives

The Planetary Health Diet Index (PHDI) measures adherence to the EAT-Lancet reference diet, a diet designed to promote human health, environmental sustainability and food equity. Although higher PHDI scores have been associated with lower risks of individual chronic diseases and mortality, associations with multiple long-term conditions (MLTCs) have not been evaluated.

Material and Methods

We analysed 113,209 UK Biobank participants with at least two valid 24-hour dietary recalls. PHDI scores (range 0–140) were based on the EAT-Lancet reference diet. Incident MLTC was defined as the development of ≥ 2 long-term conditions, excluding hypertension, diabetes, and obesity. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for MLTC, complex MLTC (≥3 conditions), and 10 leading non-communicable diseases, adjusting for sociodemographic, behavioural, and clinical factors.

Results

Over a median follow-up of 10.5 years, 28,052 participants developed MLTC. Each 20-point higher PHDI score was associated with a lower risk of MLTC (HR 0.93; 95% CI 0.91–0.95) and complex MLTC (0.92; 0.89–0.94). Higher adherence was also associated with lower risks of ischaemic heart disease (0.89; 0.85–0.94), chronic obstructive pulmonary disease (0.70; 0.65–0.76), kidney diseases (0.81; 0.76–0.87), chronic liver disease (0.83; 0.70–0.98), and colorectal cancer (0.87; 0.79–0.95). No associations were observed for stroke, dementia, or upper gastrointestinal cancers. There were no sex differences, but associations were stronger among more deprived and younger (<60 years of age) participants.

Conclusions

Greater adherence to the planetary health diet is associated with a lower incidence of MLTC. These findings support strategies that promote sustainable dietary patterns, aligned with the EAT-Lancet recommendations, to reduce the burden of chronic disease while also minimising harms to planetary health.

Key messages

• Greater adherence to the planetary health dietary index is not only good for the planet but also to population health.

• There are no significant differences between women and men in the benefits accrued by greater adherence to the planetary health dietary index.