Dietary Supplement Use and Colorectal Adenoma Risk in Individuals with Lynch Syndrome: The GEOLynch Cohort Study

BACKGROUND AND AIMS Individuals with Lynch syndrome have a high lifetime risk of developing colorectal tumors. In this prospective cohort study of individuals with Lynch syndrome, we examined associations between use of dietary supplements and occurrence of colorectal adenomas. MATERIALS AND METHODS Using data of 470 individuals with Lynch syndrome in a prospective cohort study, associations between dietary supplement use and colorectal adenoma risk were evaluated by calculating hazard ratios (HR) and 95% confidence intervals (CI) using cox regression models adjusted for age, sex, and number of colonoscopies during person time. Robust sandwich covariance estimation was used to account for dependency within families. RESULTS Of the 470 mismatch repair gene mutation carriers, 122 (26.0%) developed a colorectal adenoma during an overall median person time of 39.1 months. 40% of the study population used a dietary supplement. Use of any dietary supplement was not statistically significantly associated with colorectal adenoma risk (HR = 1.18; 95%CI 0.80-1.73). Multivitamin supplement use (HR = 1.15; 95%CI 0.72-1.84), vitamin C supplement use (HR = 1.57; 95%CI 0.93-2.63), calcium supplement use (HR = 0.69; 95%CI 0.25-1.92), and supplements containing fish oil (HR = 1.60; 95%CI 0.79-3.23) were also not associated with occurrence of colorectal adenomas. CONCLUSION This prospective cohort study does not show inverse associations between dietary supplement use and occurrence of colorectal adenomas among individuals with Lynch syndrome. Further research is warranted to determine whether or not dietary supplement use is associated to colorectal adenoma and colorectal cancer risk in MMR gene mutation carriers.