Vitamin C Intake From Diary Recordings and Risk of Breast Cancer in the Uk Dietary Cohort Consortium

Introduction Vitamin C intake has been inversely associated with breast cancer risk in case-control studies, but not in meta-analyses of cohort studies using Food Frequency Questionnaires. No study has assessed this relationship prospectively using food diaries which may more accurately measure intake. Methods Estimated dietary vitamin C intake was derived from 4 to 7 day food diaries pooled from five prospective studies in the UK Dietary Cohort Consortium. This nested case-control study of 851 incident breast cancer cases and 2727 matched controls examined breast cancer risk in relation to dietary vitamin C intake using conditional logistic regression adjusting for relevant covariates. Additionally, total vitamin C intake from supplements and diet was analysed in the three largest cohorts. Results No evidence of an association was observed between breast cancer risk and dietary (OR=1.00 per 60 mg/d, 95% CI 0.91 to 1.09, P trend =1.0) or total vitamin C intake (OR=1.01 per 60 mg/d, 95% CI 1.00 to 1.03, P trend =0.1) in analyses using continuous estimates or by fifths of intake. Additionally, there was no association for post-menopausal women. Conclusions This pooled analysis of individual UK women found no evidence of associations between breast cancer incidence and dietary or total vitamin C intake derived uniquely from detailed diary recordings.