B Vitamins Avert Stroke, Coronary Disease, Death

B Vitamins Avert Stroke, Coronary Disease, Death

LONDON, OntarioTaking Bvitamins may lower homocysteine levels, thereby reducing the risk of ischemicstroke, coronary disease and death, according to an efficacy analysis of theVitamin Intervention for Stroke Prevention trial (VISP).

Published in Stroke (36,11:2404-09, 2005) (http://stroke.ahajournals.org), the analysis outlinedresearchers criticisms of VISP: participants in VISP may have beenadministered folate-fortified grain products, the low-dose arm of the study mayhave been given the recommended daily intake for B12, low-B12 patients in bothstudy arms may have been treated with parenteral B12, test subjects withmalabsorption may have been administered an excessively low dose of B12, studyparticipants may have been taking vitamins outside of the study, and patientswith significant renal impairment may have failed to respond to vitamin therapy.

In the efficacy analysis of VISP, researchers excludedpatients with very low and very high B12 levels at baseline (less than 250pmol/L and greater than 637 pmol/L, respectively, representing the 25th and 95thpercentiles), in order to eliminate test subjects with B12 malabsorption,ongoing B12 supplementation outside the study and significant renal impairment.The resulting subgroup was comprised of 2,155 patients, 37 percent female, witha mean age of 66 plus or minus 10.7 years. There was a 21-percent reduction inischemic stroke, coronary disease and death in the high-B12 dose group comparedwith the low-B12 dose group. Kaplan-Meier survival analysis of the four groupsindicated patients with B12 levels at the median or higher at baseline who wererandomized to the high-B12 dose showed the best overall outcome, whereas thosewith baseline B12 levels lower than the median who were assigned to the low-B12dose had the worst general outcome.

In the era of folate fortification, B12 plays a key role invitamin therapy for total homocysteine, the researchers concluded, and higherdoses of B12, and other treatments to lower total homocysteine may be needed forsome patients.