Poster Topical Area: Vitamins and Minerals
Location: Hall D
Poster Board Number: 468
Objectives: Previous studies suggested that high supplemental vitamin C intake could be associated with an increased risk of breast cancer but others did not. Most studies had information on vitamin C intake at baseline only. Our objective was to prospectively study the association between vitamin C intake and breast cancer risk using regularly updated quantitative data.
Methods: Between 1980 and 2012, 7,286 invasive breast cancers occurred in 88,042 women from the Nurses' Health Study (NHS). Data on vitamin C intake have been collected every 2-4 years through a validated food frequency questionnaire and specific questions on dietary supplement use. Multivariate Hazard Ratios (HRs) and 95% confidence intervals (CIs) for incident invasive breast cancer were estimated with Cox models.
Results: During follow-up, 68% of participants ever reported the use of supplements containing vitamin C, including multivitamins, and 37% ever reported supplemental intake ≥400 mg/day. Total vitamin C intake was not associated with breast cancer risk (HRquintile 5 versus 1: 1.03, 95%CI: 0.95, 1.11). Dietary vitamin C intake was not associated with breast cancer risk overall (HRquintile 5 versus 1: 0.96, 95%CI: 0.89, 1.04) or in supplemental vitamin C nonusers (HRquintile 5 versus 1: 0.90, 95%CI: 0.76, 1.06). Ever supplemental vitamin C use (HR: 0.97, 95%CI: 0.91, 1.02) and current (HR: 1.04, 95%CI: 0.94, 1.13) or ever (HR: 0.98, 95%CI: 0.91, 1.05) use of doses ≥750 mg/day were not associated with breast cancer risk compared to never users. Analyses incorporating splines, lagged exposure, and stratified analyses are ongoing. Analyses will be replicated in NHS II.
Conclusions: Our results do not suggest that high supplemental vitamin C intake is associated with an increased risk of breast cancer.
Harvard T.H. Chan School of Public Health, Department of Nutrition