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(folate, folic acid, holotranscobalamin, vitamin B12, vitamin B6, vitamin B9)
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Current Understanding: |
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The reviewed studies do not provide consistent evidence for an association of B vitamin intake with risk of Alzheimer’s disease (AD). Some studies suggested an inverse association between folate levels and AD risk, but methodological limitations may have contributed to inconsistent findings across studies. Support for any association of vitamins B6 or B12 with AD was less apparent. Reviewed studies measured B vitamin status using either measures of dietary intake, usually recorded from food frequency questionnaires, or biomarker concentrations of the B vitamin itself or of a related marker as a measure of its bioavailability. Moreover, few studies addressed possible interactions between different B vitamins, or the possibility that B vitamins might have a role in preventing AD only among individuals with existing B-deficiencies. The majority of studies involved populations in the United States, where federal law mandates the fortification of flour with B vitamins and thus B vitamin deficiencies are uncommon. Additional prospective studies addressing these limitations will help clarify the issue. For a review of the putative mechanisms by which B vitamins may influence AD risk and detailed commentary on interpreting the findings below in a broader context, please view the Discussion. |
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