Objective: Few data exist regarding the association between calcium intake and adenoma recurrence, and no data exist for vitamin D. We investigated the role of dietary and supplemental sources of calcium and vitamin D in the etiology of adenoma recurrence.
Methods: Analyses were conducted among 1304 male and female participants in the Wheat Bran Fiber (WBF) trial of adenoma recurrence. Multiple logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).
Results: In the fully adjusted multivariate model, the OR for participants with dietary calcium intake above 1,068 versus those with intake below 698 mg/day was 0.56 (95% CI = 0.39-0.80; p-trend = 0.007). Calcium supplementation at doses above 200 mg/day did not affect risk of recurrence. Although a borderline inverse association between dietary vitamin D and recurrence was observed after adjustment for age and gender, the association weakened in the fully adjusted model (OR = 0.78 for individuals in the upper compared to the lower quartile; 95% CI = 0.54-1.13). No association was shown for supplemental sources of vitamin D.
Conclusions: Results of this study indicate that a higher intake of calcium decreases the risk of adenoma recurrence by approximately 45%, whereas vitamin D has no significant effect on recurrence rates.