Healthy and unhealthy plant‐based diets in relation to the incidence of colorectal cancer overall and by molecular subtypes

Abstract

Background Plant‐based foods have been recommended for health. However, not all plant foods are healthy, and little is known about the association between plant‐based diets and specific molecular subtypes of colorectal cancer (CRC). We examined the associations of healthy and unhealthy plant‐based diets with the incidence of CRC and its molecular subtypes. Methods While 123 773 participants of the Nurses’ Health Study and the Health Professionals Follow‐up Study had been followed up (3 143 158 person‐years), 3077 of them had developed CRC. Healthy and unhealthy plant‐based diet indices (hPDI and uPDI, respectively) were calculated using repeated food frequency questionnaire data. We determined the tumoural status of microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and BRAF and KRAS mutations. Results Higher hPDI was associated with lower CRC incidence (multivariable hazard ratio [HR] comparing extreme quartiles, 0.86, 95% confidence interval [CI]: 0.77, 0.96; P ‐trend = .04), whereas higher uPDI was associated with higher CRC incidence (multivariable HR comparing extreme quartiles, 1.16, 95% CI: 1.04, 1.29; P ‐trend = .005). The association of hPDI significantly differed by KRAS status ( P ‐heterogeneity = .003) but not by other tumour markers. The hPDI was associated with lower incidence of KRAS ‐wildtype CRC (multivariable HR comparing extreme quartiles, 0.74, 95% CI: 0.57, 0.96; P ‐trend = .004) but not KRAS ‐mutant CRC ( P ‐trend = .22). Conclusions While unhealthy plant‐based diet enriched with refined grains and sugar is associated with higher CRC incidence, healthy plant‐based diet rich in whole grains, fruits and vegetables is associated with lower incidence of CRC, especially KRAS ‐wildtype CRC.

Association of Healthful Plant-based Diet Adherence With Risk of Mortality and Major Chronic Diseases Among Adults in the UK

“…In contrast with our study that showed no association between hPDI and colorectal cancer risk, participants from 2 US cohorts with a higher hPDI had a significantly lower risk of colon cancer . However, point estimates for extreme quintile comparisons of 0.87 in our study and 0.86 in the US cohorts are similar, and the wider CIs in our study are likely due to the lower number of case patients (959 in the UK Biobank vs 3077 in the US cohorts).…”

“…28 In contrast with our study that showed no association between hPDI and colorectal cancer risk, participants from 2 US cohorts with a higher hPDI had a significantly lower risk of colon cancer. 29 However, point estimates for extreme quintile comparisons of 0.87 in our study and 0.86 in the US All models used age as the underlying time variable and were adjusted for sex, body mass index, race and ethnicity, physical activity level, smoking status, alcohol intake, education level, energy intake, polypharmacy index, multimorbidity index, and aspirin use, stratified by region. For myocardial infarction analyses, models were further adjusted for polygenic risk score (coronary artery disease).…”

The Crucial Roles of Diet, Microbiota, and Postbiotics in Colorectal Cancer

“…Among subgroups of ultra-processed foods, higher consumption of meat/poultry/seafood-based ready-to-eat products and sugar-sweetened beverages in men, as well as ready-to-eat/heat-mixed dishes in women, is associated with an increased risk of CRC [ 27 ]. Consumption of a plant-based diet high in refined grains and sugar was associated with a high incidence of CRC [ 28 ].…”

Causal associations between dietary factors and colorectal cancer risk: a Mendelian randomization study

“…For instance, Diets low in milk or calcium have been identified as primary contributors to the CRC disability-adjusted life years ( 6 ). Moreover, it has been found that nutritional supplements, such as omega-3 and arginine supplementation, could also modify the risk of CRC development ( 10 ).…”