Indication: Stroke

Source: Stroke, November 2005;36(11): 2404-9.

Research: A previous report from the Vitamin Intervention for Stroke Prevention trial (VISP) intention-to-treat analysis did not show efficacy of combined vitamin therapy for recurrent vascular events in patients with non-disabling stroke. After these results were published, researchers went back and analyzed a subgroup of 2155 subjects more likely to respond to treatment. For this analysis, researchers excluded patients with low and very high B12 levels at baseline (637 pmol/L, representing the 25th and 95th percentiles), to exclude those likely to have B12 malabsorption or to be taking B12 supplements outside the study and patients with significant renal impairment.

Results: When the research team compared results of low-dose vitamin versus high-dose vitamin therapy and found that high-dose vitamin supplements reduced recurrent stroke, death and heart disease by 21%. Further, when researchers subdivided patients by baseline levels of vitamin B12, thus identifying those with difficulties absorbing the vitamin, the differences between the low-dose and high-dose groups became greater. As such, researchers indicated that the response to vitamin therapy for lowering homocysteine largely depends on the vitamin B12 status of patients.