Vitamin D has been implicated in colorectal cancer (CRC) pathogenesis, but it remains unknown whether total vitamin D intake is associated with early-onset CRC and precursors diagnosed before age 50.
We prospectively examined the association between total vitamin D intake and risks of early-onset CRC and precursors among women enrolled in the Nurses’ Health Study II. Multivariable-adjusted hazard ratio (HR) and 95% confidence interval (CI) for early-onset CRC were estimated with Cox proportional hazards model. Multivariable-adjusted odds ratio (OR) and 95% CI for early-onset conventional adenoma and serrated polyp were estimated with logistic regression model.
We documented 111 incident cases of early-onset CRC during 1,250,560 person-years of follow-up (1991 to 2015). Higher total vitamin D intake was significantly associated with a reduced risk of early-onset CRC (HR for ≥450 IU/day vs <300 IU/day, 0.49; 95% CI, 0.26-0.93; P for trend = 0.01). The HR per 400 IU/day increase was 0.46 (95% CI, 0.26-0.83). The inverse association was significant and appeared more evident for dietary sources of vitamin D (HR per 400 IU/day increase, 0.34; 95% CI, 0.15-0.79) than supplemental vitamin D (HR per 400 IU/day increase, 0.77; 95% CI, 0.37-1.62). For CRC precursors, the ORs per 400 IU/day increase were 0.76 (95% CI, 0.65-0.88) for conventional adenoma (n = 1,439) and 0.85 (95% CI, 0.75-0.97) for serrated polyp (n = 1,878).
In a cohort of younger women, higher total vitamin D intake was associated with decreased risks of early-onset CRC and precursors.

Copyright © 2021 AGA Institute. Published by Elsevier Inc. All rights reserved.