Abstract
Experimental studies suggest a protective effect of B-vitamins on breast cancer risk, potentially modulated by alcohol intake. However, epidemiological studies are limited, especially regarding non-folate B-vitamins. Furthermore, few studies included quantitative assessment of supplemental intake. This prospective study aimed to investigate the associations between intakes of B-vitamins (dietary, supplemental, total) and breast cancer risk. 27,853 women aged ≥45 years from the NutriNet-Santé cohort (2009–2016) were included, with a median follow-up time of 4.2 years. Dietary data were collected using repeated 24 h records. A specific questionnaire assessed dietary supplement use over a 12-month period. A composition database of 8000 supplements was developed. Associations were characterized by multivariable Cox models, and 462 incident breast cancers were diagnosed. Dietary (HRQ4vs.Q1 = 0.74 (0.55, 0.99), P-trend = 0.05), supplemental (HRQ4vs.Q1 = 0.61 (0.38, 0.98), P-trend = 0.05), and total (HRQ4vs.Q1 = 0.67 (0.50, 0.91), P-trend = 0.01) pyridoxine intakes were inversely associated with breast cancer risk. Total thiamin intake was borderline inversely associated with breast cancer risk (HRper 1-unit increment = 0.78 (0.61, 1.00), P = 0.05). Statistically significant interactions between alcohol consumption and B-vitamin (thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, folate, and cobalamin) supplemental intake were observed, the latter being inversely associated with breast cancer risk in non-to-low alcohol drinkers but not in higher drinkers. This large prospective study, including quantitative assessment of supplemental intake, suggests a potential protective effect of pyridoxine and thiamin on breast cancer risk in middle-aged women.
Highlights
Breast cancer is the most common cancer among women in the world, with approximatively1.67 million new cases of breast cancer diagnosed in 2012; and nearly 522,000 associated deaths [1]
The present study focused on B-vitamins
The models were adjusted for red meat consumption (g/day, continuous); b Between B-vitamin supplement use and alcohol intake. In this large prospective cohort study, dietary, supplemental, and total pyridoxine intake and total thiamin intake were associated with decreased breast cancer risk
Summary
Breast cancer is the most common cancer among women in the world, with approximatively1.67 million new cases of breast cancer diagnosed in 2012; and nearly 522,000 associated deaths [1]. Experimental studies have suggested protective effects of micronutrients involved in one-carbon metabolism—such as B-vitamins (folate, thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, cobalamin)—on breast cancer risk, notably through genetic and epigenetic mechanisms. Folate has been by far the most investigated B-vitamin. A limited number of placebo-controlled randomized trials have evaluated the effect of folic acid supplementation on breast cancer risk. Few randomized controlled trials have been conducted to test the effect of other B-vitamins but cancer was not the primary outcome, and no significant effect on breast cancer risk was observed [4]. Even if randomized trials can provide evidence regarding the causality of the studied associations, observational studies provide complementary information since they are based on real exposures in terms of nutrient associations, sources (dietary, supplemental), and doses
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