A new epidemiological study has found that higher intakes of B vitamins, particularly pyridoxine (B6) and thiamin (B1), were associated with lower breast cancer risk in middle-aged women. 
Many prospective cohort studies have examined the association between intakes of folate (the most studied B vitamin) and breast cancer risk, as folate deficiency has been linked to DNA instability and hypomethylation. Although other B vitamins—thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, and cobalamin—are also involved in one-carbon metabolism or other genetic and epigenetic mechanisms, few cohort studies have investigated their association with breast cancer.
Researchers led by the Nutritional Epidemiology Research Team at Paris 13 University (Bobigny, France) recently addressed this question by evaluating data from a web-based cohort study (the NutriNet-Santé Study). The study cohort consisted of 27,853 women aged 45 years and older, whose dietary intakes and supplement use were assessed using repeated 24-hour dietary records and an open-ended questionnaire, respectively.
They found that dietary, supplemental, and total (i.e., dietary plus supplemental) pyridoxine (B6) intake and total thiamin (B1) intake were associated with decreased breast cancer risk. As important, they found that this association was modulated by alcohol consumption. The use of thiamin, riboflavin, niacin, pantothenic acid, folate, and cobalamin supplements was associated with lower breast cancer risk only in non-to-low drinkers. This association was no longer seen in women with higher alcohol intake.
The study results were published in the journal Nutrients (May 2017).
Why is this clinically important?
- The B vitamins pyridoxine and thiamin could be inversely associated with breast cancer risk in middle-aged women, is in line with current mechanistic hypotheses
- Clinicians should evaluate the intake levels of B vitamins in ‘at risk’ patients, particularly those who have higher alcohol intake
- Although results from the observation study need to be confirmed in larger cohort studies and intervention studies, clinicians should recommend patients to have adequate intake of B vitamins, preferably through a balanced diet
[1.] Egnell, M., et al., B-Vitamin Intake from Diet and Supplements and Breast Cancer Risk in Middle-Aged Women: Results from the Prospective NutriNet-Sante Cohort. Nutrients, 2017. 9(5).