In an article published online on August 10, 2009 in the American Heart Association journal Circulation, Harvard researchers report an association between higher plasma levels of vitamin B6 and a reduction in the risk of myocardial infarction (heart attack) in women.

The study included 144 participants in the ongoing Nurses' Health Study who were diagnosed with myocardial infarction. The women were each matched for age, smoking status and other factors with two participants in the same study who did not have a history of heart attack at the time of the heart attack cases' diagnoses. Stored fasting blood samples were analyzed for plasma pyridoxal 5' phosphate (PLP), which is the predominant form of vitamin B6 that exists in circulation, and homocysteine, an amino acid which, when elevated, has been associated with an increased risk of cardiovascular disease.


Higher levels of PLP were correlated with greater dietary intake of vitamin B6, lower body mass index and lower levels of homocysteine. The researchers uncovered a significant association between plasma PLP levels and reduced heart attack risk. Women whose PLP levels were among the top one-fourth of participants at greater than 70 picomoles per milliliter had a 78 percent lower adjusted risk of undergoing a heart attack compared to those whose levels were lowest at less than 27.9 pmol/mL. When the women were analyzed according to age, those aged 60 and older whose PLP levels were among the top quarter were found to have a 64 percent lower risk than those in the lowest quarter, while those who were under 60 in the top fourth of PLP had a 95 percent lower risk.


The authors remark that the study's findings are consistent with the role of vitamin B6 as a cofactor in the conversion of homocysteine to cysteine. The vitamin also plays a role in the transport of important minerals such as magnesium across cell membranes. The authors observe that the results of some research suggest that factors other than diet that control vitamin B6 levels could eventually be found to be more important in reducing heart attack risk.


The current prospective study is the first, to the authors' knowledge, to examine the relationship of vitamin B6 levels with heart attack in postmenopausal women. "Our investigation revealed that a lower fasting concentration of PLP is significantly associated with an increased risk of myocardial infarction in predominantly postmenopausal women, a relationship that may be causal," they write. "Future studies are needed to better understand both dietary and nondietary determinants of plasma and tissue vitamin B6 status and their role in the prevention of myocardial infarction and other chronic diseases."





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