Purpose: Carotenoids have been hypothesized to prevent carcinogenesis through their antioxidant and pro-vitamin A properties. We examined associations between intakes of specific carotenoids and risk of colorectal adenomas.
Methods: Among 29,363 men who reported having a lower bowel endoscopy between 1986 and 2006, 3,997 cases of colorectal adenoma were identified in the Health Professionals Follow-up Study. Participants completed food frequency questionnaires every 4 years; dietary information was cumulatively updated. The associations between carotenoid intakes and risk of colorectal adenomas overall and by anatomic site, stage, smoking status and alcohol consumption were investigated using multivariate logistic regression models.
Results: Total β-carotene and dietary β-carotene, lycopene and lutein/zeaxanthin intakes and the total carotenoid score were inversely associated with colorectal adenoma risk. The odds ratios (95 % confidence intervals) comparing the highest versus lowest quintile of intake were 0.78 (0.69-0.88) for total β-carotene, 0.72 (0.64-0.81) for dietary β-carotene, 0.83 (0.74-0.93) for lycopene, 0.86 (0.76-0.96) for lutein/zeaxanthin, and 0.87 (0.77-0.97) for the total carotenoid score. Associations for α-carotene and β-cryptoxanthin intakes were null. We did not find significant differences in the associations between intakes of each carotenoid and risk of colorectal adenoma by anatomic site or stage (all p values, test for common effects >0.10). The inverse associations we observed for total β-carotene and dietary β-carotene, lycopene, and lutein/zeaxanthin intakes and the total carotenoid score with adenoma risk also did not vary by smoking status and alcohol consumption.
Conclusion: This study found that a diet high in carotenoids was associated with a reduced risk of colorectal adenomas.