<em>Does body mass index mediate diet–associated colorectal adenoma risk in an elevated risk cohort? </em> — The Association Specialists
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  3. Does body mass index mediate diet–associated colorectal adenoma risk in an elevated risk cohort? 

Does body mass index mediate diet–associated colorectal adenoma risk in an elevated risk cohort?  (23888)

Meseret Derbew Molla 1 , Erin L Symonds 1 2 , Jean M Winter 1 , Charles M Cock 1 2 , Molla Wassie 1
  1. Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Bedford Park , Adelaide , South Australia , Australia
  2. Gastroenterology Department, Flinders Medical Centre, Southern Adelaide Local Health Network, Bedford Park, Adelaide, South Australia, Australia

Background: Unhealthy Western dietary patterns characterised by higher intake of refined grains, red and processed meat are associated with an increased risk of colorectal cancer (CRC), while healthy dietary patterns rich in whole grains, fibre, vegetables, and fruits are linked to a lower risk of CRC. However, there is limited evidence on characterisation of data-driven dietary approach and the mediating role of body mass index (BMI) in their association with adenoma risk among individuals undergoing regular CRC surveillance.

Methods: Dietary data from 1917 participants was collected from individuals undergoing regular CRC surveillance using the Australian Eating Survey, with self-reported weight and height measurements (2023-2024). Linked data provided presence or absence of adenoma at a colonoscopy close to the survey date. Dietary patterns were analysed using principal component analyses and grouped into tertiles for analyses. The association between dietary patterns and adenoma was analysed using multivariable multinomial logistic regression and the mediating role of BMI on this association was analysed using mediation model after adjusting for potential confounders. Adjusted Odds Ratio (AOR) with 95% confidence interval (CI) were reported where P <0.05 was used to declare the statistical significance.  

Results: Two dietary patterns were identified. Dietary pattern I was characterised by higher intake of vegetables, fruits, and seafood and dietary pattern II was characterised by higher intake of fast fried foods, red/processed meat and processed snacks. Being in tertile II of dietary pattern I was statistically associated with lower odds of having adenoma (adjusted odds ratio (AOR) = 0.75; 95% CI, 0.58, 0.98) compared with tertile I.  BMI did not statistically mediate this association (P = 0.802), rather the direct effect (P < 0.001) was statistically significant. No associations found with pattern II.

Conclusion: Dietary pattern I had a protective role against adenoma; however, BMI did not mediate this association.