Impacts of Plant-Based Diets on Multimorbidity Risk in Cancer and Cardiometabolic Diseases Across Age Groups

Highlight

This prospective analysis combining data from the EPIC and UK Biobank cohorts involving over 400,000 European adults aged 35 to 70 found that higher adherence to a healthful plant-based diet is associated with a significantly reduced risk of developing multimorbidity, defined as coexisting cancer and cardiometabolic diseases. The protective effect was particularly pronounced in middle-aged adults under 60 years. Conversely, an unhealthful plant-based diet correlated with increased multimorbidity risk in the UK Biobank but was not confirmed in EPIC.

Background

Multimorbidity, the coexistence of two or more chronic non-communicable diseases such as cancer, cardiovascular disease (CVD), and type 2 diabetes (T2D), represents a growing global health challenge. It complicates clinical management, reduces quality of life, and increases mortality risk. While plant-based diets have been shown to reduce the incidence of individual chronic diseases, it remains unclear whether they influence progression from an initial diagnosis to multimorbidity across the cancer and cardiometabolic spectrum. Additionally, understanding how these diet–disease relationships vary with age may refine prevention strategies for different life stages.

Study Design

This study was a large prospective cohort analysis including 407,618 participants (226,324 from the European Prospective Investigation into Cancer and Nutrition [EPIC] and 181,294 from the UK Biobank), aged 35 to 70 years at baseline recruitment across six European countries. Participants with pre-existing cancer, CVD, or T2D were excluded to focus on incident multimorbidity risk. Dietary data were collected at baseline using validated food frequency questionnaires in EPIC and through multiple 24-hour dietary recalls over approximately one year in the UK Biobank. Two dietary indices were constructed: a healthful Plant-Based Diet Index (hPDI) reflecting high consumption of nutritious plant foods, and an unhealthful Plant-Based Diet Index (uPDI) emphasizing less healthy plant foods like refined grains and sugary items.

The primary outcome was multimorbidity, defined as the development of at least two chronic diseases among cancer at any site, CVD, and T2D. The study employed multistate modeling with Cox proportional hazards regression to estimate hazard ratios (HRs) for multimorbidity per 10-point increment in diet index scores. Analyses were stratified by age groups younger than 60 years and 60 years or older to examine age-specific effects.

Key Findings

Over a median follow-up of approximately 11 years, 6,604 incident multimorbidity events were recorded. A higher hPDI was associated with a reduced risk of cancer-cardiometabolic multimorbidity in both cohorts. Specifically, in EPIC, a 10-point increase in hPDI was associated with an HR of 0.89 (95% confidence interval [CI], 0.83–0.96), and in UK Biobank, the HR was 0.81 (95% CI, 0.76–0.86), indicating approximately 11–19% lower risk. Notably, the inverse association was stronger among adults younger than 60 years. In UK Biobank, the protective effect was pronounced, with HRs of 0.71 (95% CI, 0.65–0.79) in younger participants and 0.86 (95% CI, 0.80–0.92) in older adults (p for interaction = 0.0016). In EPIC, similar trends were observed but with weaker effect size and nonsignificant interaction by age.

Regarding the unhealthful plant-based diet, UK Biobank participants showed a positive association with multimorbidity risk (HR per 10-point uPDI increment of 1.22; 95% CI, 1.16–1.29). However, this association was not replicated in the EPIC cohort (HR 1.00; 95% CI, 0.94–1.08), suggesting possible cohort differences or measurement variations.

Expert Commentary

This study provides robust epidemiological evidence supporting the protective role of healthy plant-based dietary patterns in reducing the multimorbidity burden involving cancer and cardiometabolic diseases. The use of large, well-characterized cohorts, exclusion of baseline disease cases, and advanced multistate modeling to account for disease progression strengthen causal inference.

The age-specific findings emphasize the potentially greater benefit of dietary interventions earlier in life before disease onset and progression. This is concordant with biological plausibility: plant-based diets rich in antioxidants, fiber, and phytochemicals can reduce systemic inflammation, improve metabolic and cardiovascular parameters, and modulate carcinogenesis.

The lack of replication in EPIC for the unhealthful plant-based diet index association highlights limitations including dietary assessment differences, regional dietary patterns, and residual confounding. Additionally, the observational design precludes definitive causality, and unmeasured lifestyle factors may influence outcomes. Future randomized controlled trials and mechanistic studies would be valuable for confirming and elucidating these relationships.

Conclusion

This large prospective analysis corroborates that adherence to a healthful plant-based dietary pattern is associated with a reduced risk of developing multimorbidity of cancer and cardiometabolic diseases, particularly when adopted before age 60. These findings reinforce current dietary guidelines advocating plant-forward nutrition to prevent chronic diseases and accentuate the importance of early lifestyle interventions for multimorbidity prevention. Nevertheless, further research is needed to clarify the differential effects of plant-based diet quality and to expand findings to diverse populations.

Funding and ClinicalTrials.gov

The study received funding from the Korean Government (Ministry of Science and ICT). No clinical trial registration was applicable as this analysis was based on cohort data.

References

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