Tuesday, June 20, 2017

A study reported on May 13, 2017 in the journal Nutrients revealed an association between a higher intake of pyridoxine (vitamin B6) and thiamin (vitamin B1) and a lower risk of breast cancer among older women. The study also found a decreased risk of the disease in association with greater supplemental intake of thiamin and pyridoxine, as well as with riboflavin (vitamin B2), niacin (vitamin B3), pantothenic acid (vitamin B5), folate and cobalamin (vitamin B12) among women with low or no alcohol intake.

The current study included 27,853 women aged 45 years and older who enrolled in the French NutriNet-Santé study beginning in 2009. Dietary assessments conducted during the first year of follow-up were used to calculate average baseline B vitamin intake. Supplement use was ascertained by questionnaires completed two months after enrollment.

Over a median follow-up period of 4.2 years, 78 premenopausal and 384 postmenopausal cases of breast cancer were diagnosed. Among women whose total intake of pyridoxine was among the highest 25% of subjects, there was a 33% lower adjusted risk of developing breast cancer over follow-up in comparison with those whose intake was among the lowest 25%. When pyridoxine from supplements alone was examined, the risk was 39% lower for those whose intake was highest compared to nonusers. For thiamin, intake from supplements was also associated with the strongest protective effect. Women whose supplemental thiamin intake was among the top group experienced a 39% lower risk of breast cancer than nonusers, while the highest intake from food alone was associated with a 24% lower risk compared to subjects whose intake was lowest.

For women whose intake of alcohol (which is associated with a higher risk of breast cancer when consumed in all but small amounts) was below the median in this study, supplementation with the B vitamins thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, folate or cobalamin was associated with a risk of breast cancer that was 40% to 53% lower than the risk experienced by those who did not supplement with the vitamins. No protective effect against breast cancer was associated with B vitamins from diet alone among subjects with low to no alcohol intake.

"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," Manon Egnell and colleagues conclude. "Alcohol intake may modulate the associations between B-vitamin supplement use and breast cancer risk."