Abstract
BackgroundVitamins involved in one-carbon metabolism are hypothesized to influence breast cancer (BC) risk. However, epidemiologic studies that examined associations between B vitamin intake and BC risk have provided inconsistent results. We prospectively examined, in the Italian ORDET cohort, whether B vitamin consumption was associated with risk of BC and BC subtypes.MethodsAfter a mean follow-up of 16.5 years, 391 BCs were diagnosed among 10,786 cohort women. B vitamin intakes were estimated from food frequency questionnaires. Cox proportional hazard models adjusted for energy intake and confounders, estimated hazard ratios (HR) with 95% confidence intervals (CIs) for BC according to intake.ResultsRRs were 0.61 (95% CI 0.38–0.97 highest vs. lowest quartile; P trend 0.025) for thiamine; 0.48 (95% CI 0.32–0.71; P trend <0.001) for riboflavin; 0.59 (95% CI 0.39–0.90; P trend 0.008) for vitamin B6, and 0.65 (95% CI 0.44–0.95; P trend 0.021) for folate. As regards risk of BC subtypes, high riboflavin and folate were significantly associated with lower risk of estrogen receptor positive (ER+) and progesterone receptor positive (PR+) cancers, and high thiamine was associated with lower risk of ER-PR- cancers. High riboflavin was associated with lower risk of both HER2+ and HER2- cancers, high folate with lower risk of HER2- disease, and high thiamine with HER2+ disease.ConclusionsThese findings support protective effects of thiamine and one-carbon metabolism vitamins (folate, riboflavin, and vitamin B6) against BC in general; while folate may also protect against ER+PR+ and HER2- disease; and thiamine against ER-PR-, and HER2+ disease.
Highlights
One-carbon metabolism is a network of biochemical pathways that provides methyl groups for a variety of essential biomolecules and biological processes
As regards risk of breast cancer (BC) subtypes, high riboflavin and folate were significantly associated with lower risk of estrogen receptor positive (ER+) and progesterone receptor positive (PR+) cancers, and high thiamine was associated with lower risk of ER-PR- cancers
These findings support protective effects of thiamine and one-carbon metabolism vitamins against BC in general; while folate may protect against ER+PR+ and human epidermal growth factor receptor 2 (HER2)- disease; and thiamine against ER-PR, and HER2+ disease
Summary
One-carbon metabolism is a network of biochemical pathways that provides methyl groups for a variety of essential biomolecules and biological processes. The B vitamin folate/folic acid is a major dietary source of methyl groups, whereas riboflavin (vitamin B2) and vitamin B6 are essential cofactors for enzymes involved in one-carbon metabolism that may influence methyl group bioavailability. While many epidemiological studies have investigated the effect of dietary folate intake on breast cancer risk, relatively few studies have evaluated the influence of intake of other B vitamins on risk. Studies that evaluated the influence of intake of other B vitamins on breast cancer risk have produced mixed results [8,9,10,11,12,13,14,15,16]. Vitamins involved in one-carbon metabolism are hypothesized to influence breast cancer (BC) risk. Epidemiologic studies that examined associations between B vitamin intake and BC risk have provided inconsistent results. In the Italian ORDET cohort, whether B vitamin consumption was associated with risk of BC and BC subtypes.
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