Diet and lifestyle influence colorectal adenoma recurrence. The role of dietary supplement use in colorectal adenoma recurrence remains controversial. In this prospective cohort study, we examined the association between dietary supplement use, total colorectal adenoma recurrence and advanced adenoma recurrence. Colorectal adenoma cases (n = 565) from a former case-control study, recruited between 1995 and 2002, were prospectively followed until 2008. Adenomas with a diameter of ≥1 cm and/or (tubulo)villous histology and/or with high grade dysplasia and/or ≥3 adenomas detected at the same colonic examination were considered advanced adenomas. Hazard ratios (HRs) and 95% confidence intervals (CIs) for dietary supplement users (use of any supplement during the past year) compared to nonusers and colorectal adenoma recurrence were calculated using stratified Cox proportional hazard models for counting processes and were adjusted for age, sex, educational level and number of colonoscopies during follow-up. Robust sandwich covariance estimation was used to adjust for the within subject correlation. A number of 165 out of 565 adenoma patients had at least one colorectal adenoma recurrence during a median person-time of 5.4 years and of these, 37 patients had at least one advanced adenoma. One-third of the total study population (n = 203) used a dietary supplement. Compared to no use, dietary supplement use was neither statistically significantly associated with total colorectal adenoma recurrence (HR = 1.03; 95% CI 0.79-1.34) nor with recurrent advanced adenomas (HR = 1.59; 95% CI 0.88-2.87). This prospective cohort study did not suggest an association between dietary supplement use and colorectal adenoma recurrence. What's new? People take vitamins and other dietary supplements for many reasons, but could your supplements be harmful? Heine-Bröring et al. investigated the effects of dietary supplements on colorectal adenomas, to better advise those at risk. Colorectal cancer is one of the most common types of cancer in the Western world, and one red flag for clinicians is the presence of colorectal adenomas. Patients who develop these asymptomatic growths have an increased risk of colorectal cancer. As more and more people have begun taking multivitamin supplements, it is important to know how to advise patients with recurrent colorectal adenomas regarding dietary supplements. The researchers conducted a cohort study, including 203 dietary supplement users and 362 nonusers, and looked at the relative frequency of colorectal adenomas in each group. Their results showed that taking dietary supplements such as vitamin C, calcium, or multivitamins did not reduce or increase a person's risk of colorectal adenoma recurrence. Use of B-vitamin supplements, however, were associated with an increase in total recurrent colorectal adenomas, but not with recurrent adenomas that showed advanced pathology. © 2012 UICC.