Dietary β-Carotene, Vitamin A, and Retinol Intake and Prevalence of Colorectal Adenoma: A Cross-Sectional Study and Meta-Analysis

Background/Aims: Antioxidants may offer protection against colorectal cancer, but their association with colorectal adenomas remains unclear due to variations in study design, population, and dietary factors. We investigated the relationship between dietary intake of β-carotene, vitamin A, and retinol and the prevalence of colorectal adenoma using food frequency questionnaires (FFQs) and colonoscopy data. Methods: We recruited participants undergoing elective colonoscopy across eight medical institutions. FFQs were administered prior to colonoscopy, and nutrient intakes were categorized into quartiles. Multivariate logistic regression was used to estimate odds ratios (ORs) adjusting for potential cofounders. A meta-analysis of 11 observational studies, including our own, was also conducted. Results: Among 720 eligible participants (mean age 52.44±14.30 years; body mass index 23.82±3.46 kg/m²), colorectal adenoma was identified in 266 (36.9%). Higher intake of β-carotene and vitamin A was associated with a significantly lower prevalence of colorectal adenoma (p for trend <0.05). Adjusted ORs for the highest versus lowest quartile were 0.43 (95% confidence interval [CI], 0.20 to 0.91) for β-carotene and 0.34 (95% CI, 0.15 to 0.76) for vitamin A. Conversely, higher retinol intake was linked to increased adenoma prevalence (OR, 2.16; 95% CI, 1.09 to 4.29), particularly among individuals with high-fat diets. Meta-analysis confirmed a protective association for β-carotene (OR, 0.60; 95% CI, 0.46 to 0.78), but not for vitamin A or retinol. Conclusions: We demonstrated an inverse association between β-carotene and colorectal adenoma prevalence, whereas the effects of vitamin A and retinol appeared to vary depending on dietary context. These findings highlight the complex influence of dietary pattern and nutrient sources on colorectal adenoma risk.