Background:
Vitamin D has been implicated in cancer prevention through its roles in cell regulation and apoptosis, yet evidence remains inconsistent, particularly in Asian populations. This study aimed to investigate the association between dietary vitamin D intake and total cancer mortality in Northern Vietnam.
Objectives:
To investigate the association between dietary vitamin D intake and total cancer risk in northern Vietnam.
?Methods:
We conducted a prospective cohort study of 42,146 participants aged ≥10 years from nine communities in Hanoi, Hung Yen, and Phu Tho provinces. Dietary vitamin D intake was assessed at baseline (2007) using a validated semi-quantitative food frequency questionnaire. Participants were followed for mortality outcomes until 2019 through systematic death records. Cox proportional hazards models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for demographic, lifestyle, and dietary covariates.
Results:
Over 457,228 person-years of follow-up, 556 cancer deaths were recorded. Mean daily vitamin D intake ranged from 0.2 µg/day in the lowest quintile (Q1) to 10.1 µg/day in the highest (Q5). Higher vitamin D intake was inversely associated with cancer mortality: Q5 vs. Q1 HR = 0.74 (95% CI: 0.56–0.99, p = 0.04). On a continuous scale, per-quintile HR = 0.94 (95% CI: 0.88–1.00, p = 0.04), and per-SD HR = 0.86 (95% CI: 0.78–0.96, p = 0.01). Associations were more pronounced among adults aged ≥60 years (Q5 vs. Q1 HR = 0.60, 95% CI: 0.39–0.93, p=0.02), with no clear relationship observed in younger participants. The inverse associations persisted after excluding early deaths and adjusting for calcium, phosphorus intake, and smoking status.
Conclusion:
Higher dietary vitamin D intake was significantly associated with lower cancer mortality in this Vietnamese cohort, particularly among older adults. These findings support the importance of adequate vitamin D intake for cancer prevention in aging populations.