Vitamins do little to prevent recurrent stroke
DETROIT – February 3, 2004 – A major national study testing whether
high-dose vitamins could prevent another stroke found that the vitamins
had little effect, according to a report in today’s (February 3) issue
of the Journal of the American Medical Association.
The study found nearly identical rates of recurrent strokes and heart
attacks between participants on a high dose of folic acid, B6 and B12
vitamins and those taking a low dose.
"High dose vitamin therapy had no effect on stroke prevention,
coronary heart disease events or death in this study, which was disappointing,"
said Seemant Chaturvedi, M.D., associate professor of neurology at the
Wayne State University School of Medicine and one of the study's investigators.
Dr. Chaturvedi also is director of the Wayne State University Stroke
Program.
The study, called VISP (for Vitamin Intervention for Stroke Prevention),
involved 3,680 adults who had already had a non-disabling stroke and
were being treated at one of 56 centers in the United States, Canada
and Scotland. Half the patients were assigned to the high-dose group
and half to the low-dose group.
Neither the patients nor their doctors knew which group they were in.
The daily vitamin pills were identical in outward appearance.
During the study, 8.1 percent of patients on the low vitamin dose and
8.4 percent of patients on the high dose had a second stroke, which
statistically is nearly identical.
The study found that the vitamin therapy lowered levels of homocysteine
- an amino acid - leading the investigators to say, "Findings in
other trials of an association between total homocysteine with an increased
risk of stroke and heart disease suggests that longer trials in different
populations with elevated total homocysteine may be necessary."
The study did show that in both the low dose and in the high dose vitamin
group those with a high homocysteine level at the start of the study
were the most likely to have a recurrent stroke.
Of patients in the low dose or control group, 6.7 percent had a coronary
heart disease "event," usually a heart attack, compared with
6.3 percent of patients on the high dose. Overall deaths from any cause
totaled 5.4 percent of the high dose group compared to 6.3 percent of
the low dose group.
Just after the start of the VISP, folate fortification of the U.S.
grain supply began (which increased folic acid in breads and other foods
containing grains), and became mandatory in January 1998. This "profoundly
reduced" the number of people with low levels of folate and high
total homocysteine levels, Dr. Chaturvedi said.
The study was stopped in December 2002, when the study's safety and
performance monitoring board told the funding agency, the National Institute
of Neurological Disorders and Stroke, that "there was no chance
of showing any difference between the two treatment groups during the
remaining follow up period."
With more than 1,000 medical students, WSU is among the nation's
largest medical schools. Together with its clinical partner, the Wayne
State University Physician Group, the school is a leader in patient
care and medical research in a number of areas, including cancer, genetics,
neuroscience and women's and children's health.
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