Plant-based dietary patterns and age-specific risk of multimorbidity of cancer and cardiometabolic diseases: a prospective analysis

BACKGROUND: It is currently unknown whether plant-based dietary patterns influence disease progression to multimorbidity after an initial non-communicable disease, and whether the associated risk of multimorbidity varies with age. This study aimed to investigate associations of plant-based diets with the risk of multimorbidity, defined as the co-occurrence of at least two chronic diseases in an individual (either cancer at any site, cardiovascular disease, or type 2 diabetes).

METHODS: This prospective cohort study used data from EPIC and UK Biobank across six European countries, with participants aged 35-70 years at recruitment. We excluded participants from these cohorts who had cancer, cardiovascular disease, or type 2 diabetes at baseline or those with missing data on diet or health outcomes. Data on dietary habits were assessed either at baseline through a validated dietary questionnaire about habits in the previous 12 months or through several 24-h recall questionnaires during approximately a year of follow-up. Multistate modelling with Cox regression was used to estimate the risk of multimorbidity according to a healthful plant-based diet index (hPDI) and, separately, an unhealthful plant-based diet index (uPDI). Risk differences in adults younger than 60 years and those age 60 years and older were estimated.

FINDINGS: 407 618 participants (226 324 from EPIC and 181 294 from UK Biobank) were included in this study. During a median follow-up time of 10·9 years in EPIC and 11·4 years in UK Biobank, 6604 cancer-cardiometabolic multimorbidity events occurred in both cohorts combined. A ten-point increment of the hPDI score was associated with a lower risk of multimorbidity, with a hazard ratio (HR) of 0·89 (95% CI 0·83-0·96) in EPIC and 0·81 (0·76-0·86) in UK Biobank. This inverse association was marginally weaker in older adults than in middle-aged adults in both cohorts. In UK Biobank, a ten-point increment of the hPDI score was associated with multivariable-adjusted HRs of 0·71 (95% CI 0·65-0·79) in adults younger than 60 years and 0·86 (0·80-0·92) in those aged 60 years and older (p interaction=0·0016). The respective HRs in EPIC were 0·86 (95% CI 0·78-0·95) and 0·92 (0·84-1·02; p interaction=0·32). A higher adherence to an unhealthy plant-based diet was positively associated with multimorbidity risk in UK Biobank (HR per ten-point increment of uPDI 1·22, 95% CI 1·16-1·29), but this was not replicated in EPIC (1·00, 0·94-1·08).

INTERPRETATION: A healthy plant-based diet might reduce the burden of multimorbidity of cancer and cardiometabolic diseases among middle-aged and older adults.

FUNDING: The Korean Government (Ministry of Science and ICT).