Associations of Adherence to the 2018 World Cancer Research Fund and the American Institute for Cancer Research Dietary Recommendations with Gut Microbiota and Inflammation Levels.

BACKGROUND

Whether the World Cancer Research Fund and the American Institute for Cancer Research (WCRF/AICR) dietary recommendations affect the gut microbiota and inflammatory status remains unclear. We examined the association of dietary adherence scores to the WCRF/AICR with gut microbiota and inflammation in a cross-sectional setting.

METHODS

The WCRF/AICR diet adherence scores were calculated for 151 participants (adenoma 97, non-adenoma 54) from 7-day dietary records. The gut microbiota was analyzed by 16S rRNA gene sequencing of fecal samples. The levels of inflammatory biomarkers in both blood (i.e., IL-6, IL-8, IgA, IgM, and IgG) and fecal samples (i.e., FCP) were evaluated in 97 colorectal adenoma patients who had blood samples available. Multivariable linear regression analyses were conducted to examine the association of individual and total dietary adherence scores with gut microbiota and inflammatory biomarker levels.

RESULTS

Participants with higher adherence had lower relative abundance of Proteobacteria (β = -0.041, 95%CI: -0.073, -0.009), Enterobacteriaceae (β = -0.035, 95%CI: -0.067, -0.003), and unidentified Enterobacteriaceae at the genus level (β = -0.029, 95%CI: -0.055, -0.003) compared to those with lower adherence. Plant-based food intake was positively correlated with increased abundance of Phascolarctobacterium (β = 0.013, 95%CI: 0.001, 0.026). Restricting fast food was linked to high abundance of Bacteroidaceae (β = 0.149, 95%CI: 0.040, 0.257) and Bacteroides (β = 0.149, 95%CI: 0.040, 0.257). Limiting sugary drinks was associated with reduced abundance of Lachnospiraceae (β = -0.155, 95%CI: -0.292, -0.018). Plant-based food intake (β = -0.251, 95%CI: -0.450, -0.052) and restriction of fast food (β = -0.226, 95%CI: -0.443, -0.008) were associated with reduced IGG levels in men. Alcohol restriction was linked to lower IL-6 (β = -7.095, 95%CI: -11.286, -2.903) and IL-8 (β = -7.965, 95%CI: -14.700, -1.230) levels in women, but with higher IL-6 (β = 0.918, 95%CI: 0.161, 1.675) levels in men.

CONCLUSIONS

Our findings support the association of adherence to the WCRF/AICR diet with gut microbiota and inflammation. These results need to be validated in additional prospective or interventional studies.