The association between plant protein intake and cancer risk: a prospective cohort study

To examine the association between plant protein intake and the risk of overall and site-specific cancers in a large prospective cohort.

This prospective cohort study included 192,428 participants from the UK Biobank, recruited from 2006 and followed until 2023. Plant protein consumption information was assessed using validated 24-hour dietary recalls. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of plant protein consumption with cancer risk were calculated using Cox proportional risk regression models. Nonlinear associations were tested using restricted cubic spline analysis.

During a median follow-up of 11.2 years, 22,779 cancer events were recorded. Compared to participants in the lowest quartile of plant protein intake, those in the highest quartile had HRs for overall cancer, lung cancer, renal cancer, and colorectal cancer of 0.91 (95% CI = 0.88-0.95, P < 0.001), 0.86 (95% CI = 0.73-1.00, P = 0.048), 0.69 (95% CI = 0.55-0.87, P = 0.002), and 0.89 (95% CI = 0.79-1.00, P = 0.046), respectively. Furthermore, each 10% increase in the ratio of plant protein to total daily protein was associated with a 3% lower overall cancer risk (HR = 0.97, 95% CI = 0.95-0.98, P < 0.001). Subgroup analyses suggested that the negative association was more pronounced in male. Among individuals who did not meet the WHO-recommended protein intake, a nonlinear association between plant protein intake and overall cancer risk was observed, characterized by a modest reduction in risk at moderate intake levels with no further risk reduction at higher intake levels (P for nonlinearity = 0.02).

This cohort study indicates that higher dietary plant protein intake is significantly associated with a reduced risk of overall and specific cancers, including lung, renal, and colorectal cancer. These findings support the notion that increasing the consumption of plant protein-rich foods is beneficial for health.